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Search for "Heck coupling" in Full Text gives 38 result(s) in Beilstein Journal of Organic Chemistry.
Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine
- Alessio Regni,
- Francesca Bartoccini and
- Giovanni Piersanti
Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70
- interconvertible to each other by hydration or dehydration, i.e., a plausible precursor of the allylic alcohol would be the diene, and vice versa [90]. Since both 8 and 10 are easily obtainable from 2 by Mozoroki–Heck coupling with commercially available 2-methyl-3-buten-2-ol, ester hydrolysis (LiOH in THF/H2O
Graphical Abstract
Figure 1: (a) Transformations of DMAT to different classes of ergot alkaloids. (b) and (c) Strategies for the...
Scheme 1: Synthesis of compound 5.
Scheme 2: Photoredox-catalyzed radical decarboxylative cyclization of 5.
Figure 2: Proposed reaction mechanism for photoredox-catalyzed radical decarboxylative cyclization.
Scheme 3: Synthesis of tryptophan derivatives 8 and 10.
Figure 3: Proposed reaction mechanism for photoredox-catalyzed radical decarboxylative cyclization.
Scheme 4: Methylation of 11 and the formal total synthesis of (±)-6,7-secoagroclavine.
Strategies in the synthesis of dibenzo[b,f]heteropines
- David I. H. Maier,
- Barend C. B. Bezuidenhoudt and
- Charlene Marais
Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51
- –Heck coupling Whereas Arnold et al. [30] reported the preparation of dibenzo[b,f]heteropines via consecutive Heck and Buchwald–Hartwig reactions (Scheme 11), amination may also precede the introduction of the double bond (Scheme 17). The formation of the dibenzo[b,f]heteropine skeleton by means of a
Graphical Abstract
Figure 1: Dibenzo[b,f]azepine (1a), -oxepine (1b) and -thiepine (1c) as examples of dibenzo[b,f]heteropines (1...
Figure 2: Selected pharmaceuticals with the dibenzo[b,f]azepine skeleton.
Figure 3: Examples of 10,11-dihydrodibenzo[b,f]azepine-based ligands.
Figure 4: The dibenzo[b,f]azepine moiety in dyes with properties suitable for the use in organic light emitti...
Figure 5: Selective bioactive natural products (13–18) containing the dibenzo[b,f]oxepine scaffold and Novart...
Scheme 1: Retrosynthetic approach to 5H-dibenzo[b,f]azepine (1a) from nitrotoluene (22).
Scheme 2: Oxidative coupling of o-nitrotoluene (22) and reduction of 2,2'-dinitrobibenzyl (21) to form 2,2'-d...
Scheme 3: Synthesis of 10,11-dihydro-5H-dibenzo[b,f]azepine (2a) via amine condensation.
Scheme 4: Catalytic reduction of 10,11-dihydro-5H-dibenzo[b,f]azepine (2a).
Scheme 5: The Wagner–Meerwein rearrangement of acridin-9-ylmethanol (23) into 5H-dibenzo[b,f]azepine (1a).
Scheme 6: Oxidative ring expansion of 2-(9-xanthenyl)malonates 24.
Scheme 7: Ring expansion via C–H functionalisation.
Scheme 8: The synthesis of fluorinated 5H-dibenzo[b,f]azepine 38 from isatin (32).
Scheme 9: The synthesis of substituted dibenzo[b,f]azepines 43 from indoles 39.
Scheme 10: Retrosynthetic pathways to dibenzo[b,f]azepines via Buchwald–Hartwig amination.
Scheme 11: Synthesis of dibenzo[b,f]oxepine 54 and -azepine 55 derivatives via (i) Heck reaction and (ii) Buch...
Scheme 12: Double Buchwald–Hartwig amination and thioetherification in the synthesis of tricyclic azepines 60 ...
Scheme 13: Double Buchwald–Hartwig amination towards substituted dibenzoazepines 62.
Scheme 14: Double Buchwald–Hartwig amination towards 10,11-dihydro-5H-dibenzo[b,f]azepine derivatives 71.
Scheme 15: One-pot Suzuki coupling–Buchwald–Hartwig amination.
Scheme 16: One-pot Rh/Pd-catalysed synthesis of dihydropyridobenzazepines.
Scheme 17: A retrosynthetic pathway to dibenzo[b,f]azepines via Mizoroki–Heck reaction.
Scheme 18: One-pot domino Pd-catalyzed Mizoroki–Heck–Buchwald–Hartwig synthesis of dibenzo[b,f]azepines.
Scheme 19: Dibenzo[b,f]thiapine and -oxepine synthesis via SNAr (thio)etherification, Wittig methylenation and...
Scheme 20: A retrosynthetic pathway to dibenzo[b,f]oxepines via Ullmann coupling.
Scheme 21: Ullmann-type coupling in dibenzo[b,f]oxepine synthesis.
Scheme 22: Wittig reaction and Ullmann coupling as key steps in dihydrobenz[b,f]oxepine synthesis.
Scheme 23: Pd-catalysed dibenzo[b,f]azepine synthesis via norbornene azepine intermediate 109.
Scheme 24: A simple representation of olefin metathesis resulting in transalkylidenation.
Scheme 25: Ring-closing metathesis as key step in the synthesis of dibenzo[b,f]heteropines.
Scheme 26: Alkyne–aldehyde metathesis in the synthesis of dibenzo[b,f]heteropines.
Scheme 27: Hydroarylation of 9-(2-alkynylphenyl)-9H-carbazole derivatives.
Scheme 28: Oxidative coupling of bisphonium ylide intermediate to give pacharin (13).
Scheme 29: Preparation of 10,11-dihydrodibenzo[b,f]heteropines via intramolecular Wurtz reaction.
Scheme 30: Phenol deprotonation and intramolecular etherification in the synthesis of bauhinoxepine J.
Figure 6: Functionalisation of dibenzo[b,f]azepine.
Scheme 31: Palladium-catalysed N-arylation of dibenzo[b,f]azepine.
Scheme 32: Cu- and Ni-catalysed N-arylation.
Scheme 33: N-Alkylation of dibenzo[b,f]azepine (1a) and dihydrodibenzo[b,f]azepine (2a).
Scheme 34: Preparation of methoxyiminosilbene.
Scheme 35: Synthesis of oxcarbazepine (153) from methoxy iminostilbene 151.
Scheme 36: Ring functionalisation of dihydrodibenzo[b,f]azepine.
Synthetic reactions driven by electron-donor–acceptor (EDA) complexes
- Zhonglie Yang,
- Yutong Liu,
- Kun Cao,
- Xiaobin Zhang,
- Hezhong Jiang and
- Jiahong Li
Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67
- -metal catalysts, such as in the Suzuki–Miyaura and Heck coupling reactions. Methodologies for forming different C–C bonds have recently been developed in the field of single-electron chemistry [63][64][65]. Considering that EDA-complex-initiated free-radical reactions are carried out under mild
Graphical Abstract
Scheme 1: The electron transfer process in EDA complexes.
Scheme 2: Synthesis of benzo[b]phosphorus oxide 3 initiated by an EDA complex.
Scheme 3: Mechanism of the synthesis of quinoxaline derivative 7.
Scheme 4: Synthesis of imidazole derivative 10 initiated by an EDA complex.
Scheme 5: Synthesis of sulfamoylation product 12 initiated by an EDA complex.
Scheme 6: Mechanism of the synthesis of sulfamoylation product 12.
Scheme 7: Synthesis of indole derivative 22 initiated by an EDA complex.
Scheme 8: Synthesis of perfluoroalkylated pyrimidines 26 initiated by an EDA complex.
Scheme 9: Synthesis of phenanthridine derivative 29 initiated by an EDA complex.
Scheme 10: Synthesis of cis-tetrahydroquinoline derivative 32 initiated by an EDA complex.
Scheme 11: Mechanism of the synthesis of cis-tetrahydroquinoline derivative 32.
Scheme 12: Synthesis of phenanthridine derivative 38 initiated by an EDA complex.
Scheme 13: Synthesis of spiropyrroline derivative 40 initiated by an EDA complex.
Scheme 14: Synthesis of benzothiazole derivative 43 initiated by an EDA complex.
Scheme 15: Synthesis of perfluoroalkyl-s-triazine derivative 45 initiated by an EDA complex.
Scheme 16: Synthesis of indoline derivative 47 initiated by an EDA complex.
Scheme 17: Mechanism of the synthesis of spirocyclic indoline derivative 47.
Scheme 18: Synthesis of cyclobutane product 50 initiated by an EDA complex.
Scheme 19: Mechanism of the synthesis of spirocyclic indoline derivative 50.
Scheme 20: Synthesis of 1,3-oxazolidine compound 59 initiated by an EDA complex.
Scheme 21: Synthesis of trifluoromethylated product 61 initiated by an EDA complex.
Scheme 22: Synthesis of indole alkylation product 64 initiated by an EDA complex.
Scheme 23: Synthesis of perfluoroalkylation product 67 initiated by an EDA complex.
Scheme 24: Synthesis of hydrotrifluoromethylated product 70 initiated by an EDA complex.
Scheme 25: Synthesis of β-trifluoromethylated alkyne product 71 initiated by an EDA complex.
Scheme 26: Mechanism of the synthesis of 2-phenylthiophene derivative 74.
Scheme 27: Synthesis of allylated product 80 initiated by an EDA complex.
Scheme 28: Synthesis of trifluoromethyl-substituted alkynyl product 84 initiated by an EDA complex.
Scheme 29: Synthesis of dearomatized fluoroalkylation product 86 initiated by an EDA complex.
Scheme 30: Mechanism of the synthesis of dearomatized fluoroalkylation product 86.
Scheme 31: Synthesis of C(sp3)–H allylation product 91 initiated by an EDA complex.
Scheme 32: Synthesis of perfluoroalkylation product 93 initiated by an EDA complex.
Scheme 33: Synthesis of spirocyclic indolene derivative 95 initiated by an EDA complex.
Scheme 34: Synthesis of perfluoroalkylation product 97 initiated by an EDA complex.
Scheme 35: Synthesis of alkylated indole derivative 100 initiated by an EDA complex.
Scheme 36: Mechanism of the synthesis of alkylated indole derivative 100.
Scheme 37: Synthesis of arylated oxidized indole derivative 108 initiated by an EDA complex.
Scheme 38: Synthesis of 4-ketoaldehyde derivative 111 initiated by an EDA complex.
Scheme 39: Mechanism of the synthesis of 4-ketoaldehyde derivative 111.
Scheme 40: Synthesis of perfluoroalkylated olefin 118 initiated by an EDA complex.
Scheme 41: Synthesis of alkylation product 121 initiated by an EDA complex.
Scheme 42: Synthesis of acylation product 123 initiated by an EDA complex.
Scheme 43: Mechanism of the synthesis of acylation product 123.
Scheme 44: Synthesis of trifluoromethylation product 126 initiated by an EDA complex.
Scheme 45: Synthesis of unnatural α-amino acid 129 initiated by an EDA complex.
Scheme 46: Synthesis of thioether derivative 132 initiated by an EDA complex.
Scheme 47: Synthesis of S-aryl dithiocarbamate product 135 initiated by an EDA complex.
Scheme 48: Mechanism of the synthesis of S-aryl dithiocarbamate product 135.
Scheme 49: Synthesis of thioether product 141 initiated by an EDA complex.
Scheme 50: Mechanism of the synthesis of borate product 144.
Scheme 51: Synthesis of boronation product 148 initiated by an EDA complex.
Scheme 52: Synthesis of boration product 151 initiated by an EDA complex.
Scheme 53: Synthesis of boronic acid ester derivative 154 initiated by an EDA complex.
Scheme 54: Synthesis of β-azide product 157 initiated by an EDA complex.
Scheme 55: Decarboxylation reaction initiated by an EDA complex.
Scheme 56: Synthesis of amidated product 162 initiated by an EDA complex.
Scheme 57: Synthesis of diethyl phenylphosphonate 165 initiated by an EDA complex.
Scheme 58: Mechanism of the synthesis of diethyl phenylphosphonate derivative 165.
Scheme 59: Synthesis of (Z)-2-iodovinyl phenyl ether 168 initiated by an EDA complex.
Scheme 60: Mechanism of the synthesis of (Z)-2-iodovinyl phenyl ether derivative 168.
Scheme 61: Dehalogenation reaction initiated by an EDA complex.
Progress in the total synthesis of inthomycins
- Bidyut Kumar Senapati
Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7
- . Therefore, the synthesis of inthomycin A was advanced in the racemic form. Treatment of compound (rac)-17 with aqueous ammonia gave the corresponding amide (rac)-18 in 96% yield. Heck coupling between (rac)-18 and vinylboronate pinacol ester [31] using Pd(PPh3)4/Et3N conditions provided stereoselective
Graphical Abstract
Figure 1: The inthomycins A–C (1–3) and structurally closely related compounds.
Figure 2: Syntheses of inthomycins A–C (1–3).
Scheme 1: The first total synthesis of racemic inthomycin A (rac)-1 by Whiting.
Scheme 2: Moloney’s synthesis of the phenyl analogue of inthomycin C ((rac)-3).
Scheme 3: Moloney’s synthesis of phenyl analogues of inthomycins A (rac-1) and B (rac-2).
Scheme 4: The first total synthesis of inthomycin B (+)-2 by R. J. K. Taylor.
Scheme 5: R. J. K. Taylor’s total synthesis of racemic inthomycin A (rac)-1.
Scheme 6: The first total synthesis of inthomycin C ((+)-3) by R. J. K. Taylor.
Scheme 7: The first total synthesis of naturally occurring inthomycin C ((–)-3) by Ryu et al.
Scheme 8: Preparation of E,E-iododiene (+)-84 and Z,E- iododiene 85a.
Scheme 9: Hatakeyama’s total synthesis of inthomycin A (+)-1 and inthomycin B (+)-2.
Scheme 10: Hatakeyama’s total synthesis of inthomycin C ((–)-3).
Scheme 11: Maulide’s formal synthesis of racemic inthomycin C ((rac)-3).
Scheme 12: Hale’s synthesis of dienylstannane (+)-69 and enyne (+)-82b intermediates.
Scheme 13: Hale’s total synthesis of inthomycin C ((+)-3).
Scheme 14: Hale and Hatakeyama’s resynthesis of (3R)-inthomycin C (−)-3 Mosher esters.
Scheme 15: Reddy’s formal syntheses of inthomycin C (+)-3 and inthomycin C ((−)-3).
Scheme 16: Synthesis of the cross-metathesis precursors (rac)-118 and 121.
Scheme 17: Donohoe’s total synthesis of inthomycin C ((−)-3).
Scheme 18: Synthesis of dienylboronic ester (E,E)-128.
Scheme 19: Synthesis of the alkenyl iodides (Z)- and (E)-130.
Scheme 20: Burton’s total synthesis of inthomycin B ((+)-2).
Scheme 21: Burton’s total synthesis of inthomycin C ((−)-3).
Scheme 22: Burton’s total synthesis of inthomycin A ((+)-1).
Scheme 23: Synthesis of common intermediate (Z)-(+)-143a.
Scheme 24: Synthesis of (Z)-and (E)-selective fragments (+)-145a–c.
Scheme 25: Kim’s total synthesis of inthomycins A (+)-1 and B (+)-2.
Scheme 26: Completion of total synthesis of inthomycin C ((–)-3) by Kim.
Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction
- Tony Jin,
- Malickah Hicks,
- Davis Kurdyla,
- Sabahudin Hrapovic,
- Edmond Lam and
- Audrey Moores
Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201
- Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0E9, Canada 10.3762/bjoc.16.201 Abstract In this report, chitin and chitosan nanocrystals were used as biomass-based supports for Pd nanoparticles (NPs) used as a heterogeneous catalyst for the Heck coupling reaction. By using a
- one-pot fabrication method, a Pd salt precursor was directly reduced and deposited onto these nanocrystal catalysts. Characterization of these nanocomposites showed disperse Pd NPs on the surfaces of the chitinous nanocrystals. Heck coupling model reactions revealed full product yield in relatively
- deposit Pd NPs directly onto both ChNCs and ChsNCs, and the as-made heterogeneous catalysts were tested with the Heck coupling reaction as a model for catalytic activity. Findings The fabrication of ChNC and ChsNCs was conducted using a procedure previously reported by our group (Lam) (see Supporting
Graphical Abstract
Scheme 1: Pathway for the formation of ChNC and subsequently ChsNCs from bulk chitin.
Figure 1: TEM micrographs of (a) ChNCs and (b) ChsNCs. Both samples were stained and prepared on glow-dischar...
Scheme 2: Catalyst fabrication method for the deposition of Pd NPs onto chitin (PdNP@ChNC) and chitosan (PdNP...
Figure 2: TEM micrographs of (a) PdNP@ChNCs and (b) PdNP@ChsNCs. The samples were placed on glow discharged T...
Figure 3: High-resolution X-ray photoelectron spectroscopy of the Pd 3d region of (a) PdNP@ChNC and (b) PdNP@...
Syntheses of spliceostatins and thailanstatins: a review
- William A. Donaldson
Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166
- Scheme 10. Very recently, the groups of Nimura and Arisawa reported the synthesis of a phenyl C-glucoside derivative of spliceostatin beginning from ᴅ-glucal (Scheme 12) [35]. A Heck coupling of the tris(trimethylsilyl) ether of 74 with phenylboronic acid in the presence of Pd(OAc)2 and benzoquinone (BQ
Graphical Abstract
Figure 1: Structures of spliceostatins/thailanstatins.
Scheme 1: Synthetic routes to protected (2Z,4S)-4-hydroxy-2-butenoic acid fragments.
Scheme 2: Kitahara synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 3: Koide synthesis of (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 4: Nicolaou synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 5: Jacobsen synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 6: Unproductive attempt to generate the (all-cis)-tetrahydropyranone 50.
Scheme 7: Ghosh synthesis of the C-7–C-14 (all-cis)-tetrahydropyran segment.
Scheme 8: Ghosh’s alternative route to the (all-cis)-tetrahydropyranone 50.
Scheme 9: Alternative synthesis of the dihydro-3-pyrone 58.
Scheme 10: Kitahara’s 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 11: Kitahara 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 12: Nimura/Arisawa synthesis of the C-1-phenyl segment.
Scheme 13: Ghosh synthesis of the C-1–C-6 fragment of FR901464 (1) from (R)-glyceraldehyde acetonide.
Scheme 14: Jacobsen synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 15: Koide synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 16: Ghosh synthesis of the C-1–C-5 segment 102 of thailanstatin A (7).
Scheme 17: Nicolaou synthesis of the C-1–C-9 segments of spliceostatin D (9) and thailanstatins A (7) and B (5...
Scheme 18: Ghosh synthesis of the C-1–C-6 segment 115 of spliceostatin E (10).
Scheme 19: Fragment coupling via Wittig and modified Julia olefinations by Kitahara.
Scheme 20: Fragment coupling via cross-metathesis by Koide.
Scheme 21: The Ghosh synthesis of spliceostatin A (4), FR901464 (1), spliceostatin E (10), and thailanstatin m...
Scheme 22: Arisawa synthesis of a C-1-phenyl analog of FR901464 (1).
Scheme 23: Jacobsen fragment coupling by a Pd-catalyzed Negishi coupling.
Scheme 24: Nicolaou syntheses of thailanstatin A and B (7 and 5) and spliceostatin D (9) via a Pd-catalyzed Su...
Scheme 25: The Ghosh synthesis of spliceostatin G (11) via Suzuki–Miyaura coupling.
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
- Lucas Guillemard and
- Joanna Wencel-Delord
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
- , thus rendering this methodology well suitable for the synthesis of a variety of indole derivatives. Subsequently, the panel of oxidative Heck coupling reactions via a photoredox catalytic system combined with C–H activation using Rh [74] or Ru [75] was extended by Rueping’s group. In 2014, Rueping
Graphical Abstract
Figure 1: Concept of dual synergistic catalysis.
Figure 2: Classification of catalytic systems involving two catalysts.
Figure 3: General mechanism for the dual nickel/photoredox catalytic system.
Figure 4: General mechanisms for C–H activation catalysis involving different reoxidation strategies.
Figure 5: Indole synthesis via dual C–H activation/photoredox catalysis.
Figure 6: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 7: Oxidative Heck reaction on arenes via the dual catalysis.
Figure 8: Proposed mechanism for the Heck reaction on arenes via dual catalysis.
Figure 9: Oxidative Heck reaction on phenols via the dual catalysis.
Figure 10: Proposed mechanism for the Heck reaction on phenols via dual catalysis.
Figure 11: Carbazole synthesis via dual C–H activation/photoredox catalysis.
Figure 12: Proposed mechanism for the carbazole synthesis via dual catalysis.
Figure 13: Carbonylation of enamides via the dual C–H activation/photoredox catalysis.
Figure 14: Proposed mechanism for carbonylation of enamides via dual catalysis.
Figure 15: Annulation of benzamides via the dual C–H activation/photoredox catalysis.
Figure 16: Proposed mechanism for the annulation of benzamides via dual catalysis.
Figure 17: Synthesis of indoles via the dual C–H activation/photoredox catalysis.
Figure 18: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 19: General concept of dual catalysis merging C–H activation and photoredox catalysis.
Figure 20: The first example of dual catalysis merging C–H activation and photoredox catalysis.
Figure 21: Proposed mechanism for the C–H arylation with diazonium salts via dual catalysis.
Figure 22: Dual catalysis merging C–H activation/photoredox using diaryliodonium salts.
Figure 23: Direct arylation via the dual catalytic system reported by Xu.
Figure 24: Direct arylation via dual catalytic system reported by Balaraman.
Figure 25: Direct arylation via dual catalytic system reported by Guo.
Figure 26: C(sp3)–H bond arylation via the dual Pd/photoredox catalytic system.
Figure 27: Acetanilide derivatives acylation via the dual C–H activation/photoredox catalysis.
Figure 28: Proposed mechanism for the C–H acylation with α-ketoacids via dual catalysis.
Figure 29: Acylation of azobenzenes via the dual catalysis C–H activation/photoredox.
Figure 30: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 31: Proposed mechanism for the C2-acylation of indoles with aldehydes via dual catalysis.
Figure 32: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 33: Perfluoroalkylation of arenes via the dual C–H activation/photoredox catalysis.
Figure 34: Proposed mechanism for perfluoroalkylation of arenes via dual catalysis.
Figure 35: Sulfonylation of 1-naphthylamides via the dual C–H activation/photoredox catalysis.
Figure 36: Proposed mechanism for sulfonylation of 1-naphthylamides via dual catalysis.
Figure 37: meta-C–H Alkylation of arenes via visible-light metallaphotocatalysis.
Figure 38: Alternative procedure for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 39: Proposed mechanism for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 40: C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 41: Proposed mechanism for C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 42: Undirected C–H aryl–aryl cross coupling via dual gold/photoredox catalysis.
Figure 43: Proposed mechanism for the undirected C–H aryl–aryl cross-coupling via dual catalysis.
Figure 44: Undirected C–H arylation of (hetero)arenes via dual manganese/photoredox catalysis.
Figure 45: Proposed mechanism for the undirected arylation of (hetero)arenes via dual catalysis.
Figure 46: Photoinduced C–H arylation of azoles via copper catalysis.
Figure 47: Photo-induced C–H chalcogenation of azoles via copper catalysis.
Figure 48: Decarboxylative C–H adamantylation of azoles via dual cobalt/photoredox catalysis.
Figure 49: Proposed mechanism for the C–H adamantylation of azoles via dual catalysis.
Figure 50: General mechanisms for the “classical” (left) and Cu-free variant (right) Sonogoshira reaction.
Figure 51: First example of a dual palladium/photoredox catalysis for Sonogashira-type couplings.
Figure 52: Arylation of terminal alkynes with diazonium salts via dual gold/photoredox catalysis.
Figure 53: Proposed mechanism for the arylation of terminal alkynes via dual catalysis.
Figure 54: C–H Alkylation of alcohols promoted by H-atom transfer (HAT).
Figure 55: Proposed mechanism for the C–H alkylation of alcohols promoted by HAT.
Figure 56: C(sp3)–H arylation of latent nucleophiles promoted by H-atom transfer.
Figure 57: Proposed mechanism for the C(sp3)–H arylation of latent nucleophiles promoted by HAT.
Figure 58: Direct α-arylation of alcohols promoted by H-atom transfer.
Figure 59: Proposed mechanism for the direct α-arylation of alcohols promoted by HAT.
Figure 60: C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 61: Proposed mechanism for the C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 62: C–H functionalization of nucleophiles via excited ketone/nickel dual catalysis.
Figure 63: Proposed mechanism for the C–H functionalization enabled by excited ketones.
Figure 64: Selective sp3–sp3 cross-coupling promoted by H-atom transfer.
Figure 65: Proposed mechanism for the selective sp3–sp3 cross-coupling promoted by HAT.
Figure 66: Direct C(sp3)–H acylation of amines via dual Ni/photoredox catalysis.
Figure 67: Proposed mechanism for the C–H acylation of amines via dual Ni/photoredox catalysis.
Figure 68: C–H hydroalkylation of internal alkynes via dual Ni/photoredox catalysis.
Figure 69: Proposed mechanism for the C–H hydroalkylation of internal alkynes.
Figure 70: Alternative procedure for the C–H hydroalkylation of ynones, ynoates, and ynamides.
Figure 71: Allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 72: Proposed mechanism for the allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 73: Asymmetric allylation of aldehydes via dual Cr/photoredox catalysis.
Figure 74: Proposed mechanism for the asymmetric allylation of aldehydes via dual catalysis.
Figure 75: Aldehyde C–H functionalization promoted by H-atom transfer.
Figure 76: Proposed mechanism for the C–H functionalization of aldehydes promoted by HAT.
Figure 77: Direct C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 78: Proposed mechanism for the C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 79: Direct C–H trifluoromethylation of strong aliphatic bonds promoted by HAT.
Figure 80: Proposed mechanism for the C–H trifluoromethylation of strong aliphatic bonds.
Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin: experimental and computational evidence for intramolecular and intermolecular C–F···H–C bonds
- Vuyisa Mzozoyana,
- Fanie R. van Heerden and
- Craig Grimmer
Beilstein J. Org. Chem. 2020, 16, 190–199, doi:10.3762/bjoc.16.22
- , numerous methods for the synthesis of these compounds have been developed, examples are the Pechmann condensation [10][11], Stille coupling reaction [12], Knoevenagel condensation [13], Heck coupling reaction [14], Kostanecki reaction, Baylis–Hillman reaction [15], Michael reaction [16], Suzuki–Miyaura
Graphical Abstract
Scheme 1: Synthesis of 4-(2-fluorophenyl)-7-methoxycoumarin (6).
Figure 1: 1H NMR spectra for the “aromatic” region of coumarin 6; comparison of 1H spectrum and 1H-{19F} spec...
Figure 2: 13C NMR spectra for coumarin 5 and 6; showing the splitting of the signal corresponding to C5.
Figure 3: 19F,1H-HOESY NMR spectrum for coumarin 6 illustrating two through-space interactions.
Figure 4: Superposition of single-crystal X-ray structure (red) and DFT-optimized structure (green); RMSD 0.3...
Figure 5: DFT-optimized structure for coumarin (6).
Figure 6: Plots of relative energy (black trace, no units), interatomic distance F–H5 (red trace, Å), interat...
Figure 7: Short contacts within the single-crystal X-ray structure of coumarin 6.
Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors
- Christoph W. Grathwol,
- Nathalie Wössner,
- Sören Swyter,
- Adam C. Smith,
- Enrico Tapavicza,
- Robert K. Hofstetter,
- Anja Bodtke,
- Manfred Jung and
- Andreas Link
Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214
- available naphthalene-2-ylboronic acid or (3,4-dihydronaphthalen-2-yl)boronic acid (Scheme 1). The latter was synthesized according to a literature procedure [36]. Formation of compounds 2b–h was accomplished through Heck coupling of aryl bromides with the appropriate styrenes (Scheme 2) [37]. Compounds 2b
Graphical Abstract
Figure 1: Selisistat (1) and hit compound GW435821X (2a).
Scheme 1: Reagents and conditions: a) appropriate boronic acid, Pd(PPh3)4, Na2CO3, DMF, H2O, microwave, 15 mi...
Scheme 2: Reagents and conditions: a) Pd2(dba)3 or Pd(OAc)2, P(o-tol)3, TEA, DMF, 120–140 °C, 0.7–24 h, 11–75...
Figure 2: (Left) UV–vis spectrum of 2b 50 µM in 5% DMSO (v/v) in assay buffer after varying durations of irra...
Figure 3: (Left) LC chromatogram of the LC–HRMS analysis of 2b after varying durations of irradiation with 25...
Scheme 3: Photocyclization and oxidation reaction of 2b upon UV irradiation.
Figure 4: Calculated and experimental absorption spectra of compounds (E)-2b-B (A), (Z)-2b-A (B), and product...
Scheme 4: Reagents and conditions: a) 4-fluoroaniline, oxone, HAc, 60 °C, 14 d, 42%; b) NH3, MeOH, rt, 3 d, 9...
Figure 5: (Left) UV–vis spectrum of 11, 50 µM in 5% DMSO (v/v), in assay buffer at the thermal equilibrium an...
Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage
- Gagandeep Kour Reen,
- Ashok Kumar and
- Pratibha Sharma
Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165
- Suzuki, Sonogashira and Heck coupling reactions (Scheme 48). The reaction proceeded by the formation of 1-iodoalkyne 142 which was characterized by mass and 1H NMR spetra. This iodoalkyne then formed a complex of Cu(I) with 2-AP. This was followed by migratory insertion of haloalkyne to form reactive Cu
Graphical Abstract
Figure 1: Various drugs having IP nucleus.
Figure 2: Participation percentage of various TMs for the syntheses of IPs.
Scheme 1: CuI–NaHSO4·SiO2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 2: Experimental examination of reaction conditions.
Scheme 3: One-pot tandem reaction for the synthesis of 2-haloimidazopyridines.
Scheme 4: Mechanistic scheme for the synthesis of 2-haloimidazopyridine.
Scheme 5: Copper-MOF-catalyzed three-component reaction (3-CR) for imidazo[1,2-a]pyridines.
Scheme 6: Mechanism for copper-MOF-driven synthesis.
Scheme 7: Heterogeneous synthesis via titania-supported CuCl2.
Scheme 8: Mechanism involving oxidative C–H functionalization.
Scheme 9: Heterogeneous synthesis of IPs.
Scheme 10: One-pot regiospecific synthesis of imidazo[1,2-a]pyridines.
Scheme 11: Vinyl azide as an unprecedented substrate for imidazo[1,2-a]pyridines.
Scheme 12: Radical pathway.
Scheme 13: Cu(I)-catalyzed transannulation approach for imidazo[1,5-a]pyridines.
Scheme 14: Plausible radical pathway for the synthesis of imidazo[1,5-a]pyridines.
Scheme 15: A solvent-free domino reaction for imidazo[1,2-a]pyridines.
Scheme 16: Cu-NPs-mediated synthesis of imidazo[1,2-a]pyridines.
Scheme 17: CuI-catalyzed synthesis of isoxazolylimidazo[1,2-a]pyridines.
Scheme 18: Functionalization of 4-bromo derivative via Sonogashira coupling reaction.
Scheme 19: A plausible reaction pathway.
Scheme 20: Cu(I)-catalyzed intramolecular oxidative C–H amidation reaction.
Scheme 21: One-pot synthetic reaction for imidazo[1,2-a]pyridine.
Scheme 22: Plausible reaction mechanism.
Scheme 23: Cu(OAc)2-promoted synthesis of imidazo[1,2-a]pyridines.
Scheme 24: Mechanism for aminomethylation/cycloisomerization of propiolates with imines.
Scheme 25: Three-component synthesis of imidazo[1,2-a]pyridines.
Figure 3: Scope of pyridin-2(1H)-ones and acetophenones.
Scheme 26: CuO NPS-promoted A3 coupling reaction.
Scheme 27: Cu(II)-catalyzed C–N bond formation reaction.
Scheme 28: Mechanism involving Chan–Lam/Ullmann coupling.
Scheme 29: Synthesis of formyl-substituted imidazo[1,2-a]pyridines.
Scheme 30: A tandem sp3 C–H amination reaction.
Scheme 31: Probable mechanistic approach.
Scheme 32: Dual catalytic system for imidazo[1,2-a]pyridines.
Scheme 33: Tentative mechanism.
Scheme 34: CuO/CuAl2O4/ᴅ-glucose-promoted 3-CCR.
Scheme 35: A tandem CuOx/OMS-2-based synthetic strategy.
Figure 4: Biomimetic catalytic oxidation in the presence of electron-transfer mediators (ETMs).
Scheme 36: Control experiment.
Scheme 37: Copper-catalyzed C(sp3)–H aminatin reaction.
Scheme 38: Reaction of secondary amines.
Scheme 39: Probable mechanistic pathway.
Scheme 40: Coupling reaction of α-azidoketones.
Scheme 41: Probable pathway.
Scheme 42: Probable mechanism with free energy calculations.
Scheme 43: MCR for cyanated IP synthesis.
Scheme 44: Substrate scope for the reaction.
Scheme 45: Reaction mechanism.
Scheme 46: Probable mechanistic pathway for Cu/ZnAl2O4-catalyzed reaction.
Scheme 47: Copper-catalyzed double oxidative C–H amination reaction.
Scheme 48: Application towards different coupling reactions.
Scheme 49: Reaction mechanism.
Scheme 50: Condensation–cyclization approach for the synthesis of 1,3-diarylated imidazo[1,5-a]pyridines.
Scheme 51: Optimized reaction conditions.
Scheme 52: One-pot 2-CR.
Scheme 53: One-pot 3-CR without the isolation of chalcone.
Scheme 54: Copper–Pybox-catalyzed cyclization reaction.
Scheme 55: Mechanistic pathway catalyzed by Cu–Pybox complex.
Scheme 56: Cu(II)-promoted C(sp3)-H amination reaction.
Scheme 57: Wider substrate applicability for the reaction.
Scheme 58: Plausible reaction mechanism.
Scheme 59: CuI assisted C–N cross-coupling reaction.
Scheme 60: Probable reaction mechanism involving sp3 C–H amination.
Scheme 61: One-pot MCR-catalyzed by CoFe2O4/CNT-Cu.
Scheme 62: Mechanistic pathway.
Scheme 63: Synthetic scheme for 3-nitroimidazo[1,2-a]pyridines.
Scheme 64: Plausible mechanism for CuBr-catalyzed reaction.
Scheme 65: Regioselective synthesis of halo-substituted imidazo[1,2-a]pyridines.
Scheme 66: Synthesis of 2-phenylimidazo[1,2-a]pyridines.
Scheme 67: Synthesis of diarylated compounds.
Scheme 68: CuBr2-mediated one-pot two-component oxidative coupling reaction.
Scheme 69: Decarboxylative cyclization route to synthesize 1,3-diarylimidazo[1,5-a]pyridines.
Scheme 70: Mechanistic pathway.
Scheme 71: C–H functionalization reaction of enamines to produce diversified heterocycles.
Scheme 72: A plausible mechanism.
Scheme 73: CuI-promoted aerobic oxidative cyclization reaction of ketoxime acetates and pyridines.
Scheme 74: CuI-catalyzed pathway for the formation of imidazo[1,2-a]pyridine.
Scheme 75: Mechanistic pathway.
Scheme 76: Mechanistic rationale for the synthesis of products.
Scheme 77: Copper-catalyzed synthesis of vinyloxy-IP.
Scheme 78: Regioselective product formation with propiolates.
Scheme 79: Proposed mechanism for vinyloxy-IP formation.
Scheme 80: Regioselective synthesis of 3-hetero-substituted imidazo[1,2-a]pyridines with different reaction su...
Scheme 81: Mechanistic pathway.
Scheme 82: CuI-mediated synthesis of 3-formylimidazo[1,2-a]pyridines.
Scheme 83: Radical pathway for 3-formylated IP synthesis.
Scheme 84: Pd-catalyzed urea-cyclization reaction for IPs.
Scheme 85: Pd-catalyzed one-pot-tandem amination and intramolecular amidation reaction.
Figure 5: Scope of aniline nucleophiles.
Scheme 86: Pd–Cu-catalyzed Sonogashira coupling reaction.
Scheme 87: One-pot amide coupling reaction for the synthesis of imidazo[4,5-b]pyridines.
Scheme 88: Urea cyclization reaction for the synthesis of two series of pyridines.
Scheme 89: Amidation reaction for the synthesis of imidazo[4,5-b]pyridines.
Figure 6: Amide scope.
Scheme 90: Pd NPs-catalyzed 3-component reaction for the synthesis of 2,3-diarylated IPs.
Scheme 91: Plausible mechanistic pathway for Pd NPs-catalyzed MCR.
Scheme 92: Synthesis of chromenoannulated imidazo[1,2-a]pyridines.
Scheme 93: Mechanism for the synthesis of chromeno-annulated IPs.
Scheme 94: Zinc oxide NRs-catalyzed synthesis of imidazo[1,2-a]azines/diazines.
Scheme 95: Zinc oxide-catalyzed isocyanide based GBB reaction.
Scheme 96: Reaction pathway for ZnO-catalyzed GBB reaction.
Scheme 97: Mechanistic pathway.
Scheme 98: ZnO NRs-catalyzed MCR for the synthesis of imidazo[1,2-a]azines.
Scheme 99: Ugi type GBB three-component reaction.
Scheme 100: Magnetic NPs-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 101: Regioselective synthesis of 2-alkoxyimidazo[1,2-a]pyridines catalyzed by Fe-SBA-15.
Scheme 102: Plausible mechanistic pathway for the synthesis of 2-alkoxyimidazopyridine.
Scheme 103: Iron-catalyzed synthetic approach.
Scheme 104: Iron-catalyzed aminooxygenation reaction.
Scheme 105: Mechanistic pathway.
Scheme 106: Rh(III)-catalyzed double C–H activation of 2-substituted imidazoles and alkynes.
Scheme 107: Plausible reaction mechanism.
Scheme 108: Rh(III)-catalyzed non-aromatic C(sp2)–H bond activation–functionalization for the synthesis of imid...
Scheme 109: Reactivity and selectivity of different substrates.
Scheme 110: Rh-catalyzed direct C–H alkynylation by Li et al.
Scheme 111: Suggested radical mechanism.
Scheme 112: Scandium(III)triflate-catalyzed one-pot reaction and its mechanism for the synthesis of benzimidazo...
Scheme 113: RuCl3-assisted Ugi-type Groebke–Blackburn condensation reaction.
Scheme 114: C-3 aroylation via Ru-catalyzed two-component reaction.
Scheme 115: Regioselective synthetic mechanism.
Scheme 116: La(III)-catalyzed one-pot GBB reaction.
Scheme 117: Mechanistic approach for the synthesis of imidazo[1,2-a]pyridines.
Scheme 118: Synthesis of imidazo[1,2-a]pyridine using LaMnO3 NPs under neat conditions.
Scheme 119: Mechanistic approach.
Scheme 120: One-pot 3-CR for regioselective synthesis of 2-alkoxy-3-arylimidazo[1,2-a]pyridines.
Scheme 121: Formation of two possible products under optimization of the catalysts.
Scheme 122: Mechanistic strategy for NiFe2O4-catalyzed reaction.
Scheme 123: Two-component reaction for synthesizing imidazodipyridiniums.
Scheme 124: Mechanistic scheme for the synthesis of imidazodipyridiniums.
Scheme 125: CuI-catalyzed arylation of imidazo[1,2-a]pyridines.
Scheme 126: Mechanism for arylation reaction.
Scheme 127: Cupric acetate-catalyzed double carbonylation approach.
Scheme 128: Radical mechanism for double carbonylation of IP.
Scheme 129: C–S bond formation reaction catalyzed by cupric acetate.
Scheme 130: Cupric acetate-catalyzed C-3 formylation approach.
Scheme 131: Control experiments for signifying the role of DMSO and oxygen.
Scheme 132: Mechanism pathway.
Scheme 133: Copper bromide-catalyzed CDC reaction.
Scheme 134: Extension of the substrate scope.
Scheme 135: Plausible radical pathway.
Scheme 136: Transannulation reaction for the synthesis of imidazo[1,5-a]pyridines.
Scheme 137: Plausible reaction pathway for denitrogenative transannulation.
Scheme 138: Cupric acetate-catalyzed C-3 carbonylation reaction.
Scheme 139: Plausible mechanism for regioselective C-3 carbonylation.
Scheme 140: Alkynylation reaction at C-2 of 3H-imidazo[4,5-b]pyridines.
Scheme 141: Two-way mechanism for C-2 alkynylation of 3H-imidazo[4,5-b]pyridines.
Scheme 142: Palladium-catalyzed SCCR approach.
Scheme 143: Palladium-catalyzed Suzuki coupling reaction.
Scheme 144: Reaction mechanism.
Scheme 145: A phosphine free palladium-catalyzed synthesis of C-3 arylated imidazopyridines.
Scheme 146: Palladium-mediated Buchwald–Hartwig cross-coupling reaction.
Figure 7: Structure of the ligands optimized.
Scheme 147: Palladium acetate-catalyzed direct arylation of imidazo[1,2-a]pyridines.
Scheme 148: Palladium acetate-catalyzed mechanistic pathway.
Scheme 149: Palladium acetate-catalyzed regioselective arylation reported by Liu and Zhan.
Scheme 150: Mechanism for selective C-3 arylation of IP.
Scheme 151: Pd(II)-catalyzed alkenylation reaction with styrenes.
Scheme 152: Pd(II)-catalyzed alkenylation reaction with acrylates.
Scheme 153: A two way mechanism.
Scheme 154: Double C–H activation reaction catalyzed by Pd(OAc)2.
Scheme 155: Probable mechanism.
Scheme 156: Palladium-catalyzed decarboxylative coupling.
Scheme 157: Mechanistic cycle for decarboxylative arylation reaction.
Scheme 158: Ligand-free approach for arylation of imidazo[1,2-a]pyridine-3-carboxylic acids.
Scheme 159: Mechanism for ligandless arylation reaction.
Scheme 160: NHC-Pd(II) complex assisted arylation reaction.
Scheme 161: C-3 arylation of imidazo[1,2-a]pyridines with aryl bromides catalyzed by Pd(OAc)2.
Scheme 162: Pd(II)-catalyzed C-3 arylations with aryl tosylates and mesylates.
Scheme 163: CDC reaction for the synthesis of imidazo[1,2-a]pyridines.
Scheme 164: Plausible reaction mechanism for Pd(OAc)2-catalyzed synthesis of imidazo[1,2-a]pyridines.
Scheme 165: Pd-catalyzed C–H amination reaction.
Scheme 166: Mechanism for C–H amination reaction.
Scheme 167: One-pot synthesis for 3,6-di- or 2,3,6-tri(hetero)arylimidazo[1,2-a]pyridines.
Scheme 168: C–H/C–H cross-coupling reaction of IPs and azoles catalyzed by Pd(II).
Scheme 169: Mechanistic cycle.
Scheme 170: Rh-catalyzed C–H arylation reaction.
Scheme 171: Mechanistic pathway for C–H arylation of imidazo[1,2-a]pyridine.
Scheme 172: Rh(III)-catalyzed double C–H activation of 2-phenylimidazo[1,2-a]pyridines and alkynes.
Scheme 173: Rh(III)-catalyzed mechanistic pathway.
Scheme 174: Rh(III)-mediated oxidative coupling reaction.
Scheme 175: Reactions showing functionalization of the product obtained by the group of Kotla.
Scheme 176: Mechanism for Rh(III)-catalyzed oxidative coupling reaction.
Scheme 177: Rh(III)-catalyzed C–H activation reaction.
Scheme 178: Mechanistic cycle.
Scheme 179: Annulation reactions of 2-arylimidazo[1,2-a]pyridines and alkynes.
Scheme 180: Two-way reaction mechanism for annulations reaction.
Scheme 181: [RuCl2(p-cymene)]2-catalyzed C–C bond formation reaction.
Scheme 182: Reported reaction mechanism.
Scheme 183: Fe(III) catalyzed C-3 formylation approach.
Scheme 184: SET mechanism-catalyzed by Fe(III).
Scheme 185: Ni(dpp)Cl2-catalyzed KTC coupling.
Scheme 186: Pd-catalyzed SM coupling.
Scheme 187: Vanadium-catalyzed coupling of IP and NMO.
Scheme 188: Mechanistic cycle.
Scheme 189: Selective C3/C5–H bond functionalizations by mono and bimetallic systems.
Scheme 190: rGO-Ni@Pd-catalyzed C–H bond arylation of imidazo[1,2-a]pyridine.
Scheme 191: Mechanistic pathway for heterogeneously catalyzed arylation reaction.
Scheme 192: Zinc triflate-catalyzed coupling reaction of substituted propargyl alcohols.
Heck- and Suzuki-coupling approaches to novel hydroquinone inhibitors of calcium ATPase
- Robert J. Kempton,
- Taylor A. Kidd-Kautz,
- Soizic Laurenceau and
- Stefan Paula
Beilstein J. Org. Chem. 2019, 15, 971–975, doi:10.3762/bjoc.15.94
- , followed by addition of bromide 5a, potassium phosphate and PdCl2(dppf)2 in DMF at 85 °C for 3.5 h gave the coupled product 10 in 47–63% yields (Scheme 3). In contrast to the case of the Heck coupling products (6 and 8, Scheme 2), nitrile 10 underwent facile reduction with lithium aluminium hydride. The
Graphical Abstract
Figure 1: Thapsigargin- and hydroquinone-based SERCA inhibitors.
Scheme 1: Friedel–Crafts alkylation of 4.
Scheme 2: Heck cross-coupling reactions.
Scheme 3: Suzuki approach to a tethered hydroquinone.
Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials
- Patrycja Żak and
- Cezary Pietraszuk
Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28
- chemistry), POSS are often functionalized through the chemical processes of C=C bond transformation, e.g., hydrosilylation, Heck coupling, silylative coupling and olefin metathesis. Olefin metathesis, i.e., catalytic exchange of double bonds between carbon atoms, is a powerful tool in organic synthesis. The
- subsequently modified via Heck coupling with a set of 4-substituted styrenes to give the next generation of functionalized derivatives. The authors also demonstrated the possibility of further functionalization of an amino-substituted derivative via the reaction with 3,5-dibromo or dinitrobenzoyl chloride. The
- of vinylsilanes (Scheme 1). The possibility to modify vinyl and styryl derivatives of silsesquioxanes via Heck reaction has been proved. The Heck coupling of 4-bromostyrene and vinyl-POSS derivatives leads to the formation of oligomeric products containing a silsesquioxane core in the polymer
Graphical Abstract
Figure 1: Cubic octasilsesquioxane.
Scheme 1: Reactivity of vinylsilanes in the presence of ruthenium alkylidene complexes; a) cross metathesis, ...
Figure 2: The scope and limitations of metathesis in transformations of vinyl-substituted siloxanes and silse...
Scheme 2: Application of olefin metathesis in the synthesis and modification of POSS-based materials: a) func...
Figure 3: Olefin metathesis catalysts used in transformations of silsesquioxanes.
Figure 4: Octavinyl-substituted cubic silsesquioxane (OVS) and spherosilicate.
Scheme 3: Cross metathesis of OVS with terminal olefins (stereoselectivity as discussed in the text).
Scheme 4: Cross metathesis of OVS with substituted styrenes.
Scheme 5: Modification of OVS via CM with styrenes.
Figure 5: Vinylbiphenyl chromophore-decorated cubic silsesquioxanes.
Scheme 6: Cross metathesis of OVS with carboranylstyrene.
Scheme 7: Synthesis of octakis[2-(p-carboxyphenyl)ethyl]silsesquioxane via CM and subsequent hydrogenation.
Scheme 8: Cross metathesis of monovinyl-POSS with olefins.
Scheme 9: Cross metathesis of monovinyl-POSS with highly π-conjugated substituted styrenes.
Scheme 10: Cross metathesis of monovinylgermasilsesquioxane with styrenes.
Scheme 11: Cross metathesis of DDSQ-2SiVi with olefins.
Scheme 12: Cross metathesis of DDSQ-2SiVi with substituted styrenes.
Scheme 13: Cross metathesis of (DDSQ-2GeVi) with olefins.
Scheme 14: CM of divinyl-substituted T10 and T12 with 4-bromostyrene (selected isomers are shown).
Scheme 15: Synthesis of vinylstilbene derivatives of T10 and T12 via a sequence of CM and Heck coupling.
Scheme 16: Cross metathesis of allyl-POSS with tert-butyl acrylate and (Z)-1,4-diacetoxy-but-2-ene.
Scheme 17: Cross metathesis of allyl-POSS with olefins.
Scheme 18: Acyclic diene metathesis copolymerization of DDSQ-2SiVi with diolefins.
Scheme 19: Acyclic diene metathesis copolymerization of DDSQ-2GeVi with diolefins.
Scheme 20: Ring-opening metathesis copolymerization of norbornenylethyl-POSS with norbornene.
Scheme 21: Synthesis of a polyethylene–POSS copolymer via ring-opening metathesis copolymerization of norborne...
Scheme 22: ROMP of norbornenylethyl-POSS with 1,5-cyclooctadiene.
Scheme 23: Copolymerization of POSS-functionalized norbornene with DCPD.
Scheme 24: Copolymerization of tris(norbornenylethyl)-POSS with DCPD.
Scheme 25: Copolymerization of N-(propyl-POSS)-7-oxanorbornene-5,6-dicarboximide with 3-(trifluoromethyl)pheny...
Figure 6: Homopolymers and copolymers having POSS groups attached to the main chain via flexible spacers of d...
Scheme 26: Ring-opening metathesis copolymerization of POSS-NBE with methyltetracyclododecene.
Scheme 27: Synthesis of block copolymer via ROMP by sequential monomer addition.
Scheme 28: Synthesis of a liquid crystalline polymer with POSS core in the side chain.
Scheme 29: Sequential synthesis of copolymers of polynorbornene containing POSS and PEO pendant groups.
Scheme 30: Synthesis of rodlike POSS−bottlebrush block copolymers [54].
Scheme 31: Surface-initiated ROMP producing copolymer layers on the surface of CdSe/ZnS quantum dots.
Hydroarylations by cobalt-catalyzed C–H activation
- Rajagopal Santhoshkumar and
- Chien-Hong Cheng
Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202
- (hydroarylation) is a 100% atom economical process to build fundamental alkyls and alkenes (Scheme 2) [42][43][44][45]. It is an efficient alternative to C–H alkylation reactions with alkyl halides where one equivalent of salt waste was released, and dehydrogenative Heck coupling with alkenes for the synthesis of
Graphical Abstract
Scheme 1: Cobalt-catalyzed C–H carbonylation.
Scheme 2: Hydroarylation by C–H activation.
Scheme 3: Pathways for cobalt-catalyzed hydroarylations.
Scheme 4: Co-catalyzed hydroarylation of alkynes with azobenzenes.
Scheme 5: Co-catalyzed hydroarylation of alkynes with 2-arylpyridines.
Scheme 6: Co-catalyzed addition of azoles to alkynes.
Scheme 7: Co-catalyzed addition of indoles to alkynes.
Scheme 8: Co-catalyzed hydroarylation of alkynes with imines.
Scheme 9: A plausible pathway for Co-catalyzed hydroarylation of alkynes.
Scheme 10: Co-catalyzed anti-selective C–H addition to alkynes.
Scheme 11: Co(III)-catalyzed hydroarylation of alkynes with indoles.
Scheme 12: Co(III)-catalyzed branch-selective hydroarylation of alkynes.
Scheme 13: Co(III)-catalyzed hydroarylation of terminal alkynes with arenes.
Scheme 14: Co(III)-catalyzed hydroarylation of alkynes with amides.
Scheme 15: Co(III)-catalyzed C–H alkenylation of arenes.
Scheme 16: Co-catalyzed alkylation of substituted benzamides with alkenes.
Scheme 17: Co-catalyzed switchable hydroarylation of styrenes with 2-aryl pyridines.
Scheme 18: Co-catalyzed linear-selective hydroarylation of alkenes with imines.
Scheme 19: Co-catalyzed linearly-selective hydroarylation of alkenes with N–H imines.
Scheme 20: Co-catalyzed branched-selective hydroarylation of alkenes with imines.
Scheme 21: Mechanism of Co-catalyzed hydroarylation of alkenes.
Scheme 22: Co-catalyzed intramolecular hydroarylation of indoles.
Scheme 23: Co-catalyzed asymmetric hydroarylation of alkenes with indoles.
Scheme 24: Co-catalyzed hydroarylation of alkenes with heteroarenes.
Scheme 25: Co(III)-catalyzed hydroarylation of activated alkenes with 2-phenyl pyridines.
Scheme 26: Co(III)-catalyzed C–H alkylation of arenes.
Scheme 27: Co(III)-catalyzed C2-alkylation of indoles.
Scheme 28: Co(III)-catalyzed switchable hydroarylation of alkyl alkenes with indoles.
Scheme 29: Co(III)-catalyzed C2-allylation of indoles.
Scheme 30: Co(III)-catalyzed ortho C–H alkylation of arenes with maleimides.
Scheme 31: Co(III)-catalyzed hydroarylation of maleimides with arenes.
Scheme 32: Co(III)-catalyzed hydroarylation of allenes with arenes.
Scheme 33: Co-catalyzed hydroarylative cyclization of enynes with carbonyl compounds.
Scheme 34: Mechanism for the Co-catalyzed hydroarylative cyclization of enynes with carbonyl compounds.
Scheme 35: Co-catalyzed addition of 2-arylpyridines to aromatic aldimines.
Scheme 36: Co-catalyzed addition of 2-arylpyridines to aziridines.
Scheme 37: Co(III)-catalyzed hydroarylation of imines with arenes.
Scheme 38: Co(III)-catalyzed addition of arenes to ketenimines.
Scheme 39: Co(III)-catalyzed three-component coupling.
Scheme 40: Co(III)-catalyzed hydroarylation of aldehydes.
Scheme 41: Co(III)-catalyzed addition of arenes to isocyanates.
Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis
- Gwendal Grelier,
- Benjamin Darses and
- Philippe Dauban
Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128
- Namitharan has very recently demonstrated that a one-pot palladium-catalyzed Heck coupling allows for transferring the aryl group of (diacetoxyiodo)arenes released after a metal-free methylenation reaction (Scheme 45) [110]. The latter that is performed by reacting PhI(OAc)2 with DMSO, applies to amidines 97
Graphical Abstract
Scheme 1: Strategies to address the issue of sustainability with polyvalent organoiodine reagents.
Scheme 2: Functionalization of ketones and alkenes with IBX.
Scheme 3: Functionalization of pyrroles with DMP.
Scheme 4: Catalytic benzoyloxy-trifluoromethylation reported by Szabó.
Scheme 5: Catalytic benzoyloxy-trifluoromethylation reported by Mideoka.
Scheme 6: Catalytic 1,4-benzoyloxy-trifluoromethylation of dienes.
Scheme 7: Catalytic benzoyloxy-trifluoromethylation of allylamines.
Scheme 8: Catalytic benzoyloxy-trifluoromethylation of enynes.
Scheme 9: Catalytic benzoyloxy-trifluoromethylation of allenes.
Scheme 10: Alkynylation of N-(aryl)imines with EBX for the formation of furans.
Scheme 11: Catalytic benzoyloxy-alkynylation of diazo compounds.
Scheme 12: Catalytic asymmetric benzoyloxy-alkynylation of diazo compounds.
Scheme 13: Catalytic 1,2-benzoyloxy-azidation of alkenes.
Scheme 14: Catalytic 1,2-benzoyloxy-azidation of enamides.
Scheme 15: Catalytic 1,2-benzoyloxy-iodination of alkenes.
Scheme 16: Seminal study with cyclic diaryl-λ3-iodane.
Scheme 17: Synthesis of alkylidenefluorenes from cyclic diaryl-λ3-iodanes.
Scheme 18: Synthesis of alkyne-substituted alkylidenefluorenes.
Scheme 19: Synthesis of phenanthrenes from cyclic diaryl-λ3-iodanes.
Scheme 20: Synthesis of dibenzocarbazoles from cyclic diaryl-λ3-iodanes.
Scheme 21: Synthesis of triazolophenantridines from cyclic diaryl-λ3-iodanes.
Scheme 22: Synthesis of functionalized benzoxazoles from cyclic diaryl-λ3-iodanes.
Scheme 23: Sequential difunctionalization of cyclic diaryl-λ3-iodanes.
Scheme 24: Double Suzuki–Miyaura coupling reaction of cyclic diaryl-λ3-iodanes.
Scheme 25: Synthesis of a δ-carboline from cyclic diaryl-λ3-iodane.
Scheme 26: Synthesis of N-(aryl)carbazoles from cyclic diaryl-λ3-iodanes.
Scheme 27: Synthesis of carbazoles from cyclic diaryl-λ3-iodanes.
Scheme 28: Synthesis of carbazoles and acridines from cyclic diaryl-λ3-iodanes.
Scheme 29: Synthesis of dibenzothiophenes from cyclic diaryl-λ3-iodanes.
Scheme 30: Synthesis of various sulfur heterocycles from cyclic diaryl-λ3-iodanes.
Scheme 31: Synthesis of dibenzothioheterocycles from cyclic diaryl-λ3-iodanes.
Scheme 32: Synthesis of dibenzosulfides and dibenzoselenides from cyclic diaryl-λ3-iodanes.
Scheme 33: Synthesis of dibenzosulfones from cyclic diaryl-λ3-iodanes.
Scheme 34: Seminal study with linear diaryl-λ3-iodanes.
Scheme 35: N-Arylation of benzotriazole with symmetrical diaryl-λ3-iodanes.
Scheme 36: Tandem catalytic C–H/N–H arylation of indoles with diaryl-λ3-iodanes.
Scheme 37: Tandem N-arylation/C(sp2)–H arylation with diaryl-λ3-iodanes.
Scheme 38: Catalytic intermolecular diarylation of anilines with diaryl-λ3-iodanes.
Scheme 39: Catalytic synthesis of diarylsulfides with diaryl-λ3-iodanes.
Scheme 40: α-Arylation of enolates using [bis(trifluoroacetoxy)iodo]arenes.
Scheme 41: Mechanism of the α-arylation using [bis(trifluoroacetoxy)iodo]arene.
Scheme 42: Catalytic nitrene additions mediated by [bis(acyloxy)iodo]arenes.
Scheme 43: Tandem of C(sp3)–H amination/sila-Sonogashira–Hagihara coupling.
Scheme 44: Tandem reaction using a λ3-iodane as an oxidant, a substrate and a coupling partner.
Scheme 45: Synthesis of 1,2-diarylated acrylamidines with ArI(OAc)2.
Atom-economical group-transfer reactions with hypervalent iodine compounds
- Andreas Boelke,
- Peter Finkbeiner and
- Boris J. Nachtsheim
Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108
- then oxidized to the sulfoxide G by iodosoarene C via the postulated activated sulfoxide F, releasing one equivalent of aryl iodide 2. A Chugaev-type elimination yields the olefin H, which finally affords acrylamidine 35 via Heck coupling with the iodoarene 2 with 50% AE (for R1 = H, R2 = Bn, Ar1 = Ar2
Graphical Abstract
Scheme 1: Overview of different types of iodane-based group-transfer reactions and their atom economy based o...
Scheme 2: (a) Structure of diaryliodonium salts 1. (b) Diarylation of a suitable substrate A with one equival...
Scheme 3: Synthesis of biphenyls 3 and 3’ with symmetrical diaryliodonium salts 1.
Scheme 4: Synthesis of diaryl thioethers 5.
Scheme 5: Synthesis of two distinct S-aryl dithiocarbamates 7 and 7’ from one equivalent of diaryliodonium sa...
Scheme 6: Synthesis of substituted isoindolin-1-ones 9 from 2-formylbenzonitrile 8 and the postulated reactio...
Scheme 7: Domino C-/N-arylation of indoles 10.
Scheme 8: Domino modification of N-heterocycles 12 via in situ-generated directing groups.
Scheme 9: Synthesis of triarylamines 17 through a double arylation of anilines.
Scheme 10: Selective conversion of novel aryl(imidazolyl)iodonium salts 1b to 1,5-disubstituted imidazoles 18.
Scheme 11: Selected examples for the application of cyclic diaryliodonium salts 19.
Scheme 12: Tandem oxidation–arylation sequence with (dicarboxyiodo)benzenes 20.
Scheme 13: Oxidative α-arylation via the transfer of an intact 2-iodoaryl group.
Scheme 14: Tandem ortho-iodination/O-arylation cascade with PIDA derivatives 20b.
Scheme 15: Synthesis of meta-N,N-diarylaminophenols 28 and the postulated mechanism.
Scheme 16: (Dicarboxyiodo)benzene-mediated metal-catalysed C–H amination and arylation.
Scheme 17: Postulated mechanism for the amination–arylation sequence.
Scheme 18: Auto-amination and cross-coupling of PIDA derivatives 20c.
Scheme 19: Tandem C(sp3)–H olefination/C(sp2)–H arylation.
Scheme 20: Atom efficient functionalisations with benziodoxolones 36.
Scheme 21: Atom-efficient synthesis of furans 39 from benziodoxolones 36a and their further derivatisations.
Scheme 22: Oxyalkynylation of diazo compounds 42.
Scheme 23: Enantioselective oxyalkynylation of diazo compounds 42’.
Scheme 24: Iron-catalysed oxyazidation of enamides 45.
One hundred years of benzotropone chemistry
- Arif Dastan,
- Haydar Kilic and
- Nurullah Saracoglu
Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98
- the efficient synthesis of benzotropone 11 in a good isolated yield (83%) via PdNPs@EDACs-catalyzed Heck coupling and intramolecular condensation of 2-bromobenzaldehyde (46) and methyl vinyl ketone (47) (Scheme 10) [58]. 2.2. Reactions of 4,5-benzotropone (11) 2.2.1. Reactions via the carbonyl group
Graphical Abstract
Scheme 1: Tropone (1), tropolone (2) and their resonance structures.
Figure 1: Natural products containing a tropone nucleus.
Figure 2: Possible isomers 11–13 of benzotropone.
Scheme 2: Synthesis of benzotropones 11 and 12.
Scheme 3: Oxidation products of benzotropylium fluoroborate (16).
Scheme 4: Oxidation of 7-bromo-5H-benzo[7]annulene (22).
Scheme 5: Synthesis of 4,5-benzotropone (11) using o-phthalaldehyde (27).
Scheme 6: Synthesis of 4,5-benzotropone (11) starting from oxobenzonorbornadiene 31.
Scheme 7: Acid-catalyzed cleavage of oxo-bridge of 34.
Scheme 8: Synthesis of 4,5-benzotropone (11) from o-xylylene dibromide (38).
Scheme 9: Synthesis of 4,5-benzotropone (11) via the carbene adduct 41.
Scheme 10: Heck coupling strategy for the synthesis of 11.
Scheme 11: Synthesis of benzofulvalenes via carbonyl group of 4,5-benzotropone (11).
Figure 3: Some cycloheptatrienylium cations.
Scheme 12: Synthesis of condensation product 63 and its subsequent oxidative cyclization products.
Figure 4: A novel series of benzo[7]annulenes prepared from 4,5-benzotropone (11).
Scheme 13: Preparation of substituted benzo[7]annulene 72 using the Mukaiyama-Michael reaction.
Figure 5: Possible benzo[7]annulenylidenes 73–75.
Scheme 14: Thermal and photochemical decomposition of 7-diazo-7H-benzo[7]annulene (76) and the trapping of int...
Scheme 15: Synthesis of benzoheptafulvalene 86.
Scheme 16: Synthesis of 7-(diphenylmethylene)-7H-benzo[7]annulene (89).
Scheme 17: Reaction of 4,5-benzotropone (11) with dimethyl diazomethane.
Scheme 18: Synthesis of dihydrobenzomethoxyazocine 103.
Scheme 19: Synthesis and reducibility of benzo-homo-2-methoxyazocines.
Scheme 20: Synthesis of 4,5-benzohomotropones 104 and 115 from 4,5-benzotropones 11 and 113.
Scheme 21: A catalytic deuterogenation of 4,5-benzotropone (11) and synthesis of 5-monosubstituted benzo[7]ann...
Scheme 22: Synthesis of methyl benzo[7]annulenes 131 and 132.
Scheme 23: Ambident reactivity of halobenzo[7]annulenylium cations 133a/b.
Scheme 24: Preparation of benzo[7]annulenylidene–iron complexes 147.
Scheme 25: Synthesis of 1-ethynylbenzotropone (150) and the etheric compound 152 from 4,5-benzotropone (11) wi...
Scheme 26: Thermal decomposition of 4,5-benzotropone (11).
Scheme 27: Reaction of 4,5-benzotropone (11) with 1,2-ethanediol and 1,2-ethanedithiol.
Scheme 28: Conversions of 1-benzosuberone (162) to 2,3-benzotropone (12).
Scheme 29: Synthesis strategies for 2,3-bezotropone (12) using 1-benzosuberones.
Scheme 30: Oxidation-based synthesis of 2,3-benzotropone (12) via 1-benzosuberone (162).
Scheme 31: Synthesis of 2,3-benzotropone (12) from α-tetralone (171) via ring-expansion.
Scheme 32: Preparation of 2,3-benzotropone (12) by using of benzotropolone 174.
Figure 6: Benzoheptafulvenes as condensation products of 2,3-benzotropone (12).
Scheme 33: Conversion of 2,3-benzotropone (12) to tosylhydrazone salt 182 and gem-dichloride 187.
Figure 7: Benzohomoazocines 191–193 and benzoazocines 194–197.
Scheme 34: From 2,3-benzotropone (12) to carbonium ions 198–201.
Scheme 35: Cycloaddition reactions of 2,3-benzotropone (12).
Scheme 36: Reaction of 2,3-benzotropone (12) with various reagents and compounds.
Figure 8: 3,4-Benzotropone (13) and its resonance structure.
Scheme 37: Synthesis of 6,7-benzobicyclo[3.2.0]hepta-3,6-dien-2-one (230).
Figure 9: Photolysis and thermolysis products of 230.
Figure 10: Benzotropolones and their tautomeric structures.
Scheme 38: Synthesis strategies of 4,5-benzotropolone (238).
Scheme 39: Synthesis protocol for 2-hydroxy-4,5-benzotropone (238) using oxazole-benzo[7]annulene 247.
Figure 11: Some quinoxaline and pyrazine derivatives 254–256 prepared from 4,5-benzotropolone (238).
Scheme 40: Nitration product of 4,5-benzotropolone (238) and its isomerization to 1-nitro-naphthoic acid (259)....
Scheme 41: Synthesis protocol for 6-hydroxy-2,3-benzotropone (239) from benzosuberone (162).
Scheme 42: Various reactions via 6-hydroxy-2,3-benzotropone (239).
Scheme 43: Photoreaction of 6-hydroxy-2,3-benzotropone (239).
Scheme 44: Synthesis of 7-hydroxy-2,3-benzotropone (241) from benzosuberone (162).
Scheme 45: Synthesis strategy for 7-hydroxy-2,3-benzotropone (241) from ketone 276.
Scheme 46: Synthesis of 7-hydroxy-2,3-benzotropone (241) from β-naphthoquinone (280).
Scheme 47: Synthesis of 7-hydroxy-2,3-benzotropone (241) from bicyclic endoperoxide 213.
Scheme 48: Synthesis of 7-hydroxy-2,3-benzotropone (241) by ring-closing metathesis.
Figure 12: Various monosubstitution products 289–291 of 7-hydroxy-2,3-benzotropone (241).
Scheme 49: Reaction of 7-hydroxy-2,3-benzotropone (241) with various reagents.
Scheme 50: Synthesis of 4-hydroxy-2,3-benzotropones 174 and 304 from diketones 300/301.
Scheme 51: Catalytic hydrogenation of diketones 300 and 174.
Scheme 52: Synthesis of halo-benzotropones from alkoxy-naphthalenes 306, 307 and 310.
Figure 13: Unexpected byproducts 313–315 during synthesis of chlorobenzotropone 309.
Figure 14: Some halobenzotropones and their cycloadducts.
Scheme 53: Multisep synthesis of 2-chlorobenzotropone 309.
Scheme 54: A multistep synthesis of 2-bromo-benzotropone 26.
Scheme 55: A multistep synthesis of bromo-2,3-benzotropones 311 and 316.
Scheme 56: Oxidation reactions of 8-bromo-5H-benzo[7]annulene (329) with some oxidants.
Scheme 57: Synthesis of 2-bromo-4,5-benzotropone (26).
Scheme 58: Synthesis of 6-chloro-2,3-benzotropone (335) using LiCl and proposed intermediate 336.
Scheme 59: Reaction of 7-bromo-2,3-benzotropone (316) with methylamine.
Scheme 60: Reactions of bromo-2,3-benzotropones 26 and 311 with dimethylamine.
Scheme 61: Reactions of bromobenzotropones 311 and 26 with NaOMe.
Scheme 62: Reactions of bromobenzotropones 26 and 312 with t-BuOK in the presence of DPIBF.
Scheme 63: Cobalt-catalyzed reductive cross-couplings of 7-bromo-2,3-benzotropone (316) with cyclic α-bromo en...
Figure 15: Cycloadduct 357 and its di-π-methane rearrangement product 358.
Scheme 64: Catalytic hydrogenation of 2-chloro-4,5-benzotropone (311).
Scheme 65: Synthesis of dibromo-benzotropones from benzotropones.
Scheme 66: Bromination/dehydrobromination of benzosuberone (162).
Scheme 67: Some transformations of isomeric dibromo-benzotropones 261A/B.
Scheme 68: Transformations of benzotropolone 239B to halobenzotropolones 369–371.
Figure 16: Bromobenzotropolones 372–376 and 290 prepared via bromination/dehydrobromination strategy.
Scheme 69: Synthesis of some halobenzotropolones 289, 377 and 378.
Figure 17: Bromo-chloro-derivatives 379–381 prepared via chlorination.
Scheme 70: Synthesis of 7-iodo-3,4-benzotropolone (382).
Scheme 71: Hydrogenation of bromobenzotropolones 369 and 370.
Scheme 72: Debromination reactions of mono- and dibromides 290 and 375.
Figure 18: Nitratation and oxidation products of some halobenzotropolenes.
Scheme 73: Azo-coupling reactions of some halobenzotropolones 294, 375 and 378.
Figure 19: Four possible isomers of dibenzotropones 396–399.
Figure 20: Resonance structures of tribenzotropone (400).
Scheme 74: Two synthetic pathways for tribenzotropone (400).
Scheme 75: Synthesis of tribenzotropone (400) from dibenzotropone 399.
Scheme 76: Synthesis of tribenzotropone (400) from 9,10-phenanthraquinone (406).
Scheme 77: Synthesis of tribenzotropone (400) from trifluoromethyl-substituted arene 411.
Figure 21: Dibenzosuberone (414).
Figure 22: Reduction products 415 and 416 of tribenzotropone (400).
Figure 23: Structures of tribenzotropone dimethyl ketal 417 and 4-phenylfluorenone (412) and proposed intermed...
Figure 24: Structures of benzylidene- and methylene-9H-tribenzo[a,c,e][7]annulenes 419 and 420 and chiral phos...
Figure 25: Structures of tetracyclic alcohol 422, p-quinone methide 423 and cation 424.
Figure 26: Structures of host molecules 425–427.
Scheme 78: Synthesis of non-helical overcrowded derivatives syn/anti-431.
Figure 27: Hexabenzooctalene 432.
Figure 28: Structures of possible eight isomers 433–440 of naphthotropone.
Scheme 79: Synthesis of naphthotropone 437 starting from 1-phenylcycloheptene (441).
Scheme 80: Synthesis of 10-hydroxy-11H-cyclohepta[a]naphthalen-11-one (448) from diester 445.
Scheme 81: Synthesis of naphthotropone 433.
Scheme 82: Synthesis of naphthotropones 433 and 434 via cycloaddition reaction.
Scheme 83: Synthesis of naphthotropone 434 starting from 452.
Figure 29: Structures of tricarbonyl(tropone)irons 458, and possible cycloadducts 459.
Scheme 84: Synthesis of naphthotropone 436.
Scheme 85: Synthesis of precursor 465 for naphthotropone 435.
Scheme 86: Generation of naphthotropone 435 from 465.
Figure 30: Structures of tropylium cations 469 and 470.
Figure 31: Structures of tropylium ions 471+.BF4−, 472+.BF4−, and 473+.BF4−.
Scheme 87: Synthesis of tropylium ions 471+.BF4− and 479+.ClO4−.
Scheme 88: Synthesis of 1- and 2-methylanthracene (481 and 482) via carbene–carbene rearrangement.
Figure 32: Trapping products 488–490.
Scheme 89: Generation and chemistry of a naphthoannelated cycloheptatrienylidene-cycloheptatetraene intermedia...
Scheme 90: Proposed intermediates and reaction pathways for adduct 498.
Scheme 91: Exited-state intramolecular proton transfer of 505.
Figure 33: Benzoditropones 506 and 507.
Scheme 92: Synthesis of benzoditropone 506e.
Scheme 93: Synthetic approaches for dibenzotropone 507 via tropone (1).
Scheme 94: Formation mechanisms of benzoditropone 507 and 516 via 515.
Scheme 95: Synthesis of benzoditropones 525 and 526 from pyromellitic dianhydride (527).
Figure 34: Possible three benzocyclobutatropones 534–536.
Scheme 96: Synthesis of benzocyclobutatropones 534 and 539.
Scheme 97: Synthesis attempts for benzocyclobutatropone 545.
Scheme 98: Generation and trapping of symmetric benzocyclobutatropone 536.
Scheme 99: Synthesis of chloro-benzocyclobutatropone 552 and proposed mechanism of fluorenone derivatives.
Scheme 100: Synthesis of tropolone analogue 559.
Scheme 101: Synthesis of tropolones 561 and 562.
Figure 35: o/p-Tropoquinone rings (563 and 564) and benzotropoquinones (565–567).
Scheme 102: Synthesis of benzotropoquinone 566.
Scheme 103: Synthesis of benzotropoquinone 567 via a Diels–Alder reaction.
Figure 36: Products 575–577 through 1,2,3-benzotropoquinone hydrate 569.
Scheme 104: Structures 578–582 prepared from tropoquinone 567.
Figure 37: Two possible structures 583 and 584 for dibenzotropoquinone, and precursor compound 585 for 583.
Scheme 105: Synthesis of saddle-shaped ketone 592 using dibenzotropoquinone 584.
Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib
- Jingbo Yu,
- Zikun Hong,
- Xinjie Yang,
- Yu Jiang,
- Zhijiang Jiang and
- Weike Su
Beilstein J. Org. Chem. 2018, 14, 786–795, doi:10.3762/bjoc.14.66
- , PR China 10.3762/bjoc.14.66 Abstract A mechanically-activated chemoselective Heck coupling for the synthesis of 3-vinylindazoles has been developed with the aid of catalytic amounts of TBAB and NaBr as both dehalogenation restrainer and grinding auxiliary. After tuning of the chemical conditions and
- [33][34] and axitinib [35][36][37][38] (Scheme 1). Mechanochemistry as a burgeoning technique to promote solvent-free reactions has led to remarkable advances [39][40][41][42], particularly for cross-coupling reactions [43][44][45], involving Heck coupling with the aid of stoichiometric amounts of
- -2H-pyran-2-yl)-1H-indazole (3q) in 90% yield. Next, sequential two-step Heck coupling and Migita coupling under ball milling conditions selectively afforded THP-axitinib 7. Finally, deprotection of 7 with p-TsOH gave axitinib in a total yield of 44% (41% [66]). Comparing to previous synthetic
Graphical Abstract
Scheme 1: Representative pharmaceutically useful indazoles.
Scheme 2: Model Heck reaction of 3-bromo-N-methyl-1H-indazole (1a) and n-butyl acrylate (2a). (173 stainless-...
Figure 1: Investigation of additives in the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), Pd(OAc)2 (5 mol %),...
Scheme 3: The control experiments. aTEA (1.8 mmol), silica gel (5.0 g), bPd(OAc)2 (5 mol %), PPh3 (10 mol %),...
Scheme 4: Plausible reaction pathway.
Figure 2: Influence of milling time and rotation speed on the Heck reaction: 1a (1.5 mmol), 2a (2.25 mmol), P...
Figure 3: Influence of the milling ball filling degree with different size on the Heck reaction: 1a (1.5 mmol...
Scheme 5: Examination of the substrate scope. Reaction conditions: 1 (1.5 mmol), 2 (2.25 mmol), Pd(OAc)2 (5 m...
Scheme 6: Synthesis of axitinib by mechanochemical Heck–Migita coupling. Reagents and conditions: (i) NBS, Na...
An efficient Pd–NHC catalyst system in situ generated from Na2PdCl4 and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water
- Nan Sun,
- Meng Chen,
- Liqun Jin,
- Wei Zhao,
- Baoxiang Hu,
- Zhenlu Shen and
- Xinquan Hu
Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168
- mol % Na2PdCl4, Pd/L = 1:1 (molar ratio), 1.5 mL H2O, 100 °C. Reusability of the Na2PdCl4/L1 catalytic system for the catalytic Mizoroki–Heck coupling reaction of 4-bromoacetophene (1a) and styrene (2a). The synthetic route for the preparation of imidazolium salts L1–L3. Optimizing the reaction
Graphical Abstract
Figure 1: Structures of imidazolium salts L1–L3.
Scheme 1: The synthetic route for the preparation of imidazolium salts L1–L3.
Figure 2: Kinetic profiles of Mizoroki–Heck reactions in water, Na2PdCl4/L1 (square), L2 (circle), and L3 (tr...
Figure 3: Reusability of the Na2PdCl4/L1 catalytic system for the catalytic Mizoroki–Heck coupling reaction o...
An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation
- Carolina S. García,
- Paula M. Uberman and
- Sandra E. Martín
Beilstein J. Org. Chem. 2017, 13, 1717–1727, doi:10.3762/bjoc.13.166
- Mizoroki–Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The
- particular, Pd NPs have been well-established as catalysts in the Mizoroki–Heck coupling reaction, obtaining the desired products in good to high yields, finding some examples in aqueous solution and under microwave (MW) irradiation [26][27][28][29][30][31][32][33][34][35][36]. Besides these studies, there
- organic reactions could be increased, and better selectivities of the products achieved, but also the homogeneous mixing of the reactants in water could be enhanced, on the basic of the efficient ability to absorb MW energy by water [44]. The use of water in combination with MW heating for Heck coupling
Graphical Abstract
Scheme 1: Synthesis of (E)-pterostilbene (19) catalyzed by PVP-Pd NPs.
Figure 1: Reuse experiments of PdNPs in the coupling reaction between 4-bromoacetophenone (1a) and styrene (2a...
Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill
- Wei Shi,
- Jingbo Yu,
- Zhijiang Jiang,
- Qiaoling Shao and
- Weike Su
Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160
- , ICP–MS and XPS suggest that Pd/MgAl-LDHs have excellent textural properties with zero-valence Pd on its layers. The reaction results indicate that the catalyst could be utilized in HSBM systems to afford a wide range of Heck coupling products in satisfactory yields. Furthermore, this catalyst could be
- Information File 1). The Heck coupling reaction under HSBM conditions m-Bromoacetophenone (1a) and styrene (2a) were chosen as the model reactants (Scheme 2), catalyzed by Pd/MgAl-LDHs under ball-milling conditions with silica gel (5 g) and stainless-steel balls (ΦMB = 0.2, dMB = 14 mm) at 800 rpm. Based on
Graphical Abstract
Scheme 1: Supported catalysts in cross-coupling reactions. MM represents mixer mill; PM represents planetary ...
Figure 1: The XRD patterns for the samples of MgAl-LDHs, MgAl-LDHs-PdCl42− and Pd/MgAl-LDHs.
Scheme 2: Selected model reaction.
Figure 2: Examination of the milling-ball filling degree (ΦMB) and milling-ball sizes on the yield of 3aa. Re...
Figure 3: Examination of ball-milling time and rotation speed on the yield of 3aa. Reaction conditions: 1a (1...
Figure 4: Substrate scope of Pd/MgAl-LDHs catalyzed Heck reactions. Reaction conditions unless otherwise note...
Scheme 3: Pd/MgAl-LDHs catalyzed Heck reactions of heteroaryl bromides. Reaction conditions unless otherwise ...
Figure 5: Recycling studies of the Pd/MgAl-LDH catalyst for Heck reactions. Reaction conditions: 1i or 1m (1....
Total syntheses of the archazolids: an emerging class of novel anticancer drugs
- Stephan Scheeff and
- Dirk Menche
Beilstein J. Org. Chem. 2017, 13, 1085–1098, doi:10.3762/bjoc.13.108
- synthesis, also on highly elaborate substrates. Considerable efforts were invested before the challenging Heck coupling with the thiazole fragment 6 could be effected with useful selectivities. Besides the desired E,E-diene 34 formation of other double bond isomers both in the southern and northern part of
- reactions to set both the characteristic assemblies of neighbored methyl and hydroxy group bearing stereogenic centers. In addition, an aldol condensation was shown to enable an efficient route for construction of a delicate triene system. The final E-selective Heck coupling on a highly elaborate substrate
Graphical Abstract
Scheme 1: Molecular structures of the archazolids.
Scheme 2: Retrosynthetic analysis of archazolid A by the Menche group.
Scheme 3: Synthesis of north-eastern fragment 5 through a Paterson anti-aldol addition and multiple Still–Gen...
Scheme 4: Synthesis of 4 through an Abiko–Masamune anti-aldol addition.
Scheme 5: Thiazol construction and synthesis of the southern fragment 6.
Scheme 6: Completion of the total synthesis of archazolid A.
Scheme 7: Synthesis of archazolid B (2) by a ring closing Heck reaction of 38.
Scheme 8: Retrosynthetic analysis of archazolid B by the Trauner group.
Scheme 9: Synthesis of acid 40 from Roche ester 41 involving a highly efficient Trost–Alder ene reaction.
Scheme 10: Synthesis of precursor 39 for the projected relay RCM reaction.
Scheme 11: Final steps of Trauner’s total synthesis of archazolid B.
Scheme 12: Overview of the different retrosynthetic approaches for the synthesis of dihydroarchazolid B (3) re...
Scheme 13: Fragment synthesis of 69 towards the total synthesis of 3.
Scheme 14: Organometallic addition of the side chain to access free alcohol 75.
A strategic approach to [6,6]-bicyclic lactones: application towards the CD fragment of DHβE
- Tue Heesgaard Jepsen,
- Emil Glibstrup,
- François Crestey,
- Anders A. Jensen and
- Jesper Langgaard Kristensen
Beilstein J. Org. Chem. 2017, 13, 988–994, doi:10.3762/bjoc.13.98
- the Mizoroki–Heck coupling. We were aware that we would perhaps face a greater challenge in terms of generating the desired 6-membered exocyclic product rather than the undesired 7-membered endocyclic product [18]. Starting from commercially available propargylamine, tosylated compound 1 was prepared
Graphical Abstract
Figure 1: DHβE and related structures. The Ki values of the compounds at the rat α4β2 nAChR subtype determine...
Scheme 1: First strategy towards the CD fragment (Ts-strategy). i) TsCl, TEA, DCM, 0 °C. ii) NaH, DMF, 0 °C, ...
Scheme 2: First strategy towards the CD fragment (Cbz-strategy). i) R-Cl, TEA, CH2Cl2, 0 °C. ii) NaH, DMF, 0 ...
Scheme 3: Second strategy towards the CD fragment. i) 4-Bromobut-1-ene, K2CO3, acetone, 70 °C. ii) n-BuLi, TH...
Figure 2: The binding affinities of compounds 9 and 26 at the rat α4β2 nAChR. a) The AB fragment was evaluate...
Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions
- Michal Medvecký,
- Igor Linder,
- Luise Schefzig,
- Hans-Ulrich Reissig and
- Reinhold Zimmer
Beilstein J. Org. Chem. 2016, 12, 2898–2905, doi:10.3762/bjoc.12.289
- [36] in Heck reactions [37][38][39][40][41][42] is also of interest, since these coupling products are useful intermediates for the synthesis of non-proteinogenic amino acids [43]. To our delight, the Heck coupling of syn-4a and 16 could be efficiently achieved employing Jeffery´s conditions [44
Graphical Abstract
Scheme 1: Access to enantiopure 3,6-dihydro-1,2-oxazines 3 via lithiated alkoxyallenes 1 and carbohydrate-der...
Scheme 2: Iodination of 1,2-oxazines syn-3a–c and anti-3a,d leading to 5-iodo-substituted 1,2-oxazines syn-4a...
Scheme 3: Sonogashira reactions of 4-methoxy-1,2-oxazines syn-4a, anti-4a and anti-4d leading to 5-alkynyl-su...
Scheme 4: Sonogashira reactions of D-glyceraldehyde-derived 1,2-oxazines syn-4a–c leading to 5-alkynyl-substi...
Scheme 5: Heck reactions of 1,2-oxazine syn-4a leading to 5-alkenyl-substituted 1,2-oxazines syn-13, syn-14 a...
Scheme 6: Suzuki–Miyaura reactions of 1,2-oxazines syn-4a, syn-4b and anti-4d leading to 5-styryl-substituted...
Scheme 7: Cross-coupling reaction of 1,2-oxazine anti-4d leading to 5-cyano-substituted 1,2-oxazine anti-25.
Scheme 8: Desilylation of 1,2-oxazine syn-5 and subsequent click reaction with benzyl azide leading to 5-(1,2...
Scheme 9: Hydrogenation of 1,2-oxazine syn-21 leading to γ-amino alcohols 27a,b and subsequent ring closure t...
Scheme 10: Hydrogenation of 1,2-oxazine anti-24 to products anti-29 and anti-30.
Selected synthetic strategies to cyclophanes
- Sambasivarao Kotha,
- Mukesh E. Shirbhate and
- Gopalkrushna T. Waghule
Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142
- Heck coupling: In 2003, Snieckus and co-workers [97] have synthesized the seco-C/D ring analogues of ergot alkaloids through the intramolecular Heck reaction as a key step. The coupling precursors 63 and 68 were prepared from 4-bromoindoles by a sequential Vilsmeier–Haack, Henry nitroaldol condensation
Graphical Abstract
Figure 1: General representation of cyclophanes.
Figure 2: cyclophanes one or more with heteroatom.
Figure 3: Metathesis catalysts 12–17 and C–C coupling catalyst 18.
Figure 4: Natural products containing the cyclophane skeleton.
Figure 5: Turriane family of natural products.
Scheme 1: Synthesis of [3]ferrocenophanes through Mannich reaction. Reagents and conditions: (i) excess HNMe2...
Scheme 2: Synthesis of cyclophanes through Michael addition. Reagents and conditions: (i) xylylene dibromide,...
Scheme 3: Synthesis of normuscopyridine analogue 37 through an oxymercuration–oxidation strategy. Reagents an...
Scheme 4: Synthesis of tribenzocyclotriyne 39 through Castro–Stephens coupling reaction. Reagents and conditi...
Scheme 5: Synthesis of cyclophane 43 through Glaser–Eglinton coupling. Reagents and conditions: (i) 9,10-bis(...
Scheme 6: Synthesis of the macrocyclic C-glycosyl cyclophane through Glaser coupling. Reagents and conditions...
Scheme 7: Synthesis of cyclophane-containing complex 49 through Glaser–Eglinton coupling reaction. Reagents a...
Scheme 8: Synthesis of cyclophane 53 through Glaser–Eglinton coupling. Reagents and conditions: (i) K2CO3, ac...
Figure 6: Cyclophanes 54–56 that have been synthesized through Glaser–Eglinton coupling.
Figure 7: Synthesis of tetrasubstituted [2.2]paracyclophane 57 and chiral cyclophyne 58 through Eglinton coup...
Scheme 9: Synthesis of cyclophane through Glaser–Hay coupling reaction. Reagents and conditions: (i) CuCl2 (1...
Scheme 10: Synthesis of seco-C/D ring analogs of ergot alkaloids through intramolecular Heck reaction. Reagent...
Scheme 11: Synthesis of muscopyridine 73 via Kumada coupling. Reagents and conditions: (i) 72, THF, ether, 20 ...
Scheme 12: Synthesis of the cyclophane 79 via McMurry coupling. Reagents and conditions: (i) 75, decaline, ref...
Scheme 13: Synthesis of stilbenophane 81 via McMurry coupling. Reagents and conditions: (i) TiCl4, Zn, pyridin...
Scheme 14: Synthesis of stilbenophane 85 via McMurry coupling. Reagents and conditions: (i) NBS (2 equiv), ben...
Figure 8: List of cyclophanes prepared via McMurry coupling reaction as a key step.
Scheme 15: Synthesis of paracyclophane by cross coupling involving Pd(0) catalyst. Reagents and conditions: (i...
Scheme 16: Synthesis of the cyclophane 112 via the pinacol coupling and 113 by RCM. Reagents and conditions: (...
Scheme 17: Synthesis of cyclophane derivatives 122a–c via Sonogoshira coupling. Reagents and conditions: (i) C...
Scheme 18: Synthesis of cyclophane 130 via Suzuki–Miyaura reaction as a key step. Reagents and conditions: (i)...
Scheme 19: Synthesis of the mycocyclosin via Suzuki–Miyaura cross coupling. Reagents and conditions: (i) benzy...
Scheme 20: Synthesis of cyclophanes via Wurtz coupling reaction Reagents and conditions: (i) PhLi, Et2O, C6H6,...
Scheme 21: Synthesis of non-natural glycophanes using alkyne metathesis. Reagents and conditions: (i) G-I (12)...
Figure 9: Synthesis of cyclophanes via ring-closing alkyne metathesis.
Scheme 22: Synthesis of crownophanes by cross-enyne metathesis. Reagents and conditions: (i) G-II (13), 5 mol ...
Scheme 23: Synthesis of (−)-cylindrocyclophanes A (156) and (−)-cylindrocyclophanes F (155). Reagents and cond...
Scheme 24: Synthesis of cyclophane 159 derivatives via SM cross-coupling and RCM. Reagents and conditions: (i)...
Scheme 25: Sexithiophene synthesis via cross metathesis. Reagents and conditions: (i) 161, Pd(PPh3)4, K2CO3, T...
Scheme 26: Synthesis of pyrrole-based cyclophane using enyne metathesis. Reagents and conditions: (i) Se, chlo...
Scheme 27: Synthesis of macrocyclic derivatives by RCM. Reagents and conditions: (i) G-I/G-II, CH2Cl2, 0.005 M...
Scheme 28: Synthesis of enantiopure β-lactam-based dienyl bis(dihydrofuran) 179. Reagents and conditions: (i) ...
Scheme 29: Synthesis of a [1.1.6]metaparacyclophane derivative 183 via SM cross coupling. Reagents and conditi...
Scheme 30: Synthesis of a [1.1.6]metaparacyclophane derivative 190 via SM cross coupling. Reagents and conditi...
Scheme 31: Template-promoted synthesis of cyclophanes involving RCM. Reagents and conditions: (i) acenaphthene...
Scheme 32: Synthesis of [3.4]cyclophane derivatives 200 via SM cross coupling and RCM. Reagents and conditions...
Figure 10: Examples for cyclophanes synthesized by RCM.
Scheme 33: Synthesis of the longithorone C framework assisted by fluorinated auxiliaries. Reagents and conditi...
Scheme 34: Synthesis of the longithorone framework via RCM. Reagents and conditions: (i) 213, NaH, THF, rt, 10...
Scheme 35: Synthesis of floresolide B via RCM as a key step. Reagents and conditions: (i) G-II (13, 0.1 equiv)...
Scheme 36: Synthesis of normuscopyridine (223) by the RCM strategy. Reagents and condition: (i) Mg, THF, hexen...
Scheme 37: Synthesis of muscopyridine (73) via RCM. Reagents and conditions: (i) 225, NaH, THF, 0 °C to rt, 1....
Scheme 38: Synthesis of muscopyridine (73) via RCM strategy. Reagents and conditions: (i) NaH, n-BuLi, 5-bromo...
Scheme 39: Synthesis of pyridinophane derivatives 223 and 245. Reagents and conditions: (i) PhSO2Na, TBAB, CH3...
Scheme 40: Synthesis of metacyclophane derivatives 251 and 253. Reagents and conditions: (i) 240, NaH, THF, rt...
Scheme 41: Synthesis of normuscopyridine and its higher analogues. Reagents and conditions: (i) alkenyl bromid...
Scheme 42: Synthesis of fluorinated ferrocenophane 263 via a [2 + 2] cycloaddition. Reagents and conditions: (...
Scheme 43: Synthesis of [2.n]metacyclophanes 270 via a [2 + 2] cycloaddition. Reagents and conditions: (i) Ac2...
Scheme 44: Synthesis of metacyclophane 273 by a [2 + 2 + 2] co-trimerization. Reagents and conditions: (i) [Rh...
Scheme 45: Synthesis of paracyclophane 276 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditions: ...
Scheme 46: Synthesis of cyclophane 278 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditions: (i) ...
Scheme 47: Synthesis of cyclophane 280 via a [2 + 2 + 2] cycloaddition. Reagents and conditions: (i) [(Rh(cod)(...
Scheme 48: Synthesis of taxane framework by a [2 + 2 + 2] cycloaddition. Reagents and conditions: (i) Cp(CO)2 ...
Scheme 49: Synthesis of cyclophane 284 and 285 via a [2 + 2 + 2] cycloaddition reaction. Reagents and conditio...
Scheme 50: Synthesis of pyridinophanes 293a,b and 294a,b via a [2 + 2 + 2] cycloaddition. Reagents and conditi...
Scheme 51: Synthesis of pyridinophanes 296 and 297 via a [2 + 2 + 2] cycloaddition. Reagents and conditions: (...
Scheme 52: Synthesis of triazolophane by a 1,3-dipolar cycloaddition. Reagents and conditions: (i) propargyl b...
Scheme 53: Synthesis of glycotriazolophane 309 by a click reaction. Reagents and conditions: (i) LiOH, H2O, Me...
Figure 11: Cyclophanes 310 and 311 prepared via click chemistry.
Scheme 54: Synthesis of cyclophane via the Dötz benzannulation. Reagents and conditions: (i) THF, 100 °C, 12 h...
Scheme 55: Synthesis of [6,6]metacyclophane by a Dötz benzannulation. Reagents and conditions: (i) THF, 100 °C...
Scheme 56: Synthesis of cyclophanes by a Dötz benzannulation. Reagents and conditions: (i) THF, 65 °C, 3 h; (i...
Scheme 57: Synthesis of muscopyridine (73) via an intramolecular DA reaction of ketene. Reagents and condition...
Scheme 58: Synthesis of bis[10]paracyclophane 336 via Diels–Alder reaction. Reagents and conditions: (i) DMAD,...
Scheme 59: Synthesis of [8]paracyclophane via DA reaction. Reagents and conditions: (i) maleic anhydride, 3–5 ...
Scheme 60: Biomimetic synthesis of (−)-longithorone A. Reagents and conditions: (i) Me2AlCl, CH2Cl2, −20 °C, 7...
Scheme 61: Synthesis of sporolide B (349) via a [4 + 2] cycloaddition reaction. Reagents and conditions: (i) P...
Scheme 62: Synthesis of the framework of (+)-cavicularin (352) via a [4 + 2] cycloaddition. Reagents and condi...
Scheme 63: Synthesis of oxazole-containing cyclophane 354 via Beckmann rearrangement. Reagents and conditions:...
Scheme 64: Synthesis of cyclophanes 360a–c via benzidine rearrangement. Reagents and conditions: (i) 356a–d, K2...
Scheme 65: Synthesis of cyclophanes 365a–c via benzidine rearrangement. Reagents and conditions: (i) BocNHNH2,...
Scheme 66: Synthesis of metacyclophane 367 via Ciamician–Dennstedt rearrangement. Reagents and conditions: (i)...
Scheme 67: Synthesis of cyclophane by tandem Claisen rearrangement and RCM as key steps. Reagents and conditio...
Scheme 68: Synthesis of cyclophane derivative 380. Reagents and conditions: (i) K2CO3, CH3CN, allyl bromide, r...
Scheme 69: Synthesis of metacyclophane via Cope rearrangement. Reagents and conditions: (i) MeOH, NaBH4, rt, 1...
Scheme 70: Synthesis of cyclopropanophane via Favorskii rearrangement. Reagents and conditions: (i) Br2, CH2Cl2...
Scheme 71: Cyclophane 389 synthesis via photo-Fries rearrangement. Reagents and conditions: (i) DMAP, EDCl/CHCl...
Scheme 72: Synthesis of normuscopyridine (223) via Schmidt rearrangement. Reagents and conditions: (i) ethyl s...
Scheme 73: Synthesis of crownophanes by tandem Claisen rearrangement. Reagents and conditions: (i) diamine, Et3...
Scheme 74: Attempted synthesis of cyclophanes via tandem Claisen rearrangement and RCM. Reagents and condition...
Scheme 75: Synthesis of muscopyridine via alkylation with 2,6-dimethylpyridine anion. Reagents and conditions:...
Scheme 76: Synthesis of cyclophane via Friedel–Craft acylation. Reagents and conditions: (i) CS2, AlCl3, 7 d, ...
Scheme 77: Pyridinophane 418 synthesis via Friedel–Craft acylation. Reagents and conditions: (i) 416, AlCl3, CH...
Scheme 78: Cyclophane synthesis involving the Kotha–Schölkopf reagent 421. Reagents and conditions: (i) NBS, A...
Scheme 79: Cyclophane synthesis involving the Kotha–Schölkopf reagent 421. Reagents and conditions: (i) BEMP, ...
Scheme 80: Cyclophane synthesis by coupling with TosMIC. Reagents and conditions: (i) (a) ClCH2OCH3, TiCl4, CS2...
Scheme 81: Synthesis of diaza[32]cyclophanes and triaza[33]cyclophanes. Reagents and conditions: (i) DMF, NaH,...
Scheme 82: Synthesis of cyclophane 439 via acyloin condensation. Reagents and conditions: (i) Na, xylene, 75%;...
Scheme 83: Synthesis of multibridged binuclear cyclophane 442 by aldol condensation. Reagents and conditions: ...
Scheme 84: Synthesis of various macrolactones. Reagents and conditions: (i) iPr2EtN, DMF, 77–83%; (ii) TBDMSCl...
Scheme 85: Synthesis of muscone and muscopyridine via Yamaguchi esterification. Reagents and conditions: (i) 4...
Scheme 86: Synthesis of [5]metacyclophane via a double elimination reaction. Reagents and conditions: (i) LiBr...
Figure 12: Cyclophanes 466–472 synthesized via Hofmann elimination.
Scheme 87: Synthesis of cryptophane via Baylis–Hillman reaction. Reagents and conditions: (i) methyl acrylate,...
Scheme 88: Synthesis of cyclophane 479 via double Chichibabin reaction. Reagents and conditions: (i) excess 478...
Scheme 89: Synthesis of cyclophane 483 via double Chichibabin reaction. Reagents and conditions: (i) 481, OH−;...
Scheme 90: Synthesis of cyclopeptide via an intramolecular SNAr reaction. Reagents and conditions: (i) TBAF, T...
Scheme 91: Synthesis of muscopyridine (73) via C-zip ring enlargement reaction. Reagents and conditions: (i) H...
Figure 13: Mechanism of the formation of compound 494.
Scheme 92: Synthesis of indolophanetetraynes 501a,b using the Nicholas reaction as a key step. Reagents and co...
Scheme 93: Synthesis of cyclophane via radical cyclization. Reagents and conditions: (i) cyclododecanone, phen...
Scheme 94: Synthesis of (−)-cylindrocyclophanes A (156) and (−)-cylindrocyclophanes F (155). Reagents and cond...
Scheme 95: Cyclophane synthesis via Wittig reaction. Reagents and conditions: (i) LiOEt (2.1 equiv), THF, −78 ...
Figure 14: Representative examples of cyclophanes synthesized via Wittig reaction.
Scheme 96: Synthesis of the [6]paracyclophane via isomerization of Dewar benzene. Reagents and conditions: (i)...
Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions
- Matthieu Jouffroy,
- Rafael Gramage-Doria,
- David Sémeril,
- Dominique Armspach,
- Dominique Matt,
- Werner Oberhauser and
- Loïc Toupet
Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249
- -catalysed Mizoroki–Heck coupling reactions between aryl bromides and styrene on one hand, and the rhodium-catalysed asymmetric hydroformylation of styrene on the other hand. The inability of both chiral ligands to form standard bis(phosphine) complexes under catalytic conditions was established by high
- Mizoroki–Heck and asymmetric hydroformylation reactions. The related trans-chelating diphosphine WIDEPHOS (Figure 1) was also tested for comparison purposes in the case of the Mizoroki–Heck coupling studies. Results and Discussion Metal coordination As shown previously, HUGPHOS-1 and HUGPHOS-2 are able to
- enantioselectivities probably arise from the embracing properties of the HUGPHOS ligands, which facilitates chirality transfer. Heck cross-coupling Phosphine-assisted Heck reactions strongly depend on the bulkiness of the phosphine used [64]. To assess HUGPHOS-2 in Heck coupling, we focused on the reaction between
Graphical Abstract
Figure 1: CD-based mono- and diphosphines with inward-pointing phosphorus atoms.
Scheme 1: Complexation of a "PdCl(dmba)" unit by HUGPHOS ligands.
Scheme 2: Reaction of HUGPHOS-1 with [MCl2(PhCN)2] complexes (M = Pd, Pt). Only one isomer with a given MeO–M...
Scheme 3: Synthesis of complexes 3–5.
Figure 2: X-ray structure of aqua palladium complex 5 [44] (top: side view; bottom: view from the primary face). ...
Scheme 4: Dehydration of Pd(II) complex 5.
Figure 3: Ruthenium complexes 7 and 8 in Newman projection along the Ru–P bond.
Figure 4: Titration of HUGPHOS-1 with [Rh(CO)2Cl]2 at 25 °C.
Scheme 5: Synthesis of rhodium carbonyl complexes 9–11.
Scheme 6: Synthesis of rhodium complexes 12 and 13.
Scheme 7: Selective formation of complex 14 under 40 bar CO/H2 at 80 °C.
Figure 5: High pressure NMR spectra of 13 under CO/H2 (1:1) recorded in toluene-d8 (at various temperatures a...
Figure 6: IR spectra of 14 recorded in CH2Cl2 at 50 °C under 40 bar of CO/H2 1:1.
Figure 7: Calculated structures (Spartan 10) of trigonal bipyramidal [RhH(CO)3(HUGPHOS-2)] with the phosphoru...
Scheme 8: Possible mechanism for the hydroformylation of styrene when using monophosphine complexes 12 or 13 ...
Scheme 9: Simplified Heck coupling mechanism when using HUGPHOS-1 or HUGPHOS-2 as ligands. Doted lines stand ...
