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Search for "Ullmann coupling" in Full Text gives 19 result(s) in Beilstein Journal of Organic Chemistry.
Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles
- Jun Kikuchi,
- Roi Nakajima and
- Naohiko Yoshikai
Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79
- Suzuki–Miyaura and Sonogashira couplings on 4aa or 4ba afforded the desired products 5 and 6 in 47% and 74% yields, respectively. In the former case, the C–Br bond on the pyrazole moiety remained intact, highlighting the superior leaving group ability of the BX group. Cu-catalyzed Ullmann coupling
- between 4ba and 4-methoxybenzenethiol furnished the N,S-substituted olefin 7 in 59% yield. The treatment of 4aa with stoichiometric CuI and ʟ-proline effected the iodine(III)-to-iodine(I) conversion to give the vinyl iodide 8 in 76% yield. Compound 8 was used for the Ullmann coupling with imidazole
Graphical Abstract
Scheme 1: Synthesis of N-vinylazoles.
Scheme 2: Scope of three-component N-alkenylation of azoles.
Scheme 3: Competition experiments and plausible reaction pathway.
Scheme 4: Preparative-scale reaction and product transformations. Reaction conditions: (a) Pd(PPh3)4, 4-MeOC6H...
A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices
- Suangsiri Arunlimsawat,
- Patteera Funchien,
- Pongsakorn Chasing,
- Atthapon Saenubol,
- Taweesak Sudyoadsuk and
- Vinich Promarak
Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122
- OLED realized a maximum external quantum efficiency (EQEmax) of 3.32% with an emission peak at 659 nm. Results and Discussion The designed TPECNz molecule was synthesized by a multistep reaction as described in Scheme 1. Initially, an Ullmann coupling reaction of bromo-TPE 1 and carbazole provided TPE
Graphical Abstract
Scheme 1: Synthesis of D–A–D chromophore TPECNz.
Figure 1: a) The optimized structure and HOMO/LUMO distributions calculated by B3LYP/6-31G(d,p) method. b) Th...
Figure 2: UV–vis absorption and PL spectra in a) toluene solution (≈1 × 10−5 M) and b) thin film spin-coated ...
Figure 3: a) Normalized UV–vis absorption/PL spectra in different solvents. b) Lippert–Mataga plot of Stokes ...
Figure 4: a) PL spectra in THF/water mixtures (5 μM) with different water fractions (fw). b) Plot of relative...
Figure 5: a) DSC and TGA thermograms measured at a heating rate of 10 °C min−1 under N2 flow. b) Cyclic volta...
Figure 6: a) Schematic structure of the hole-only and electron-only MIS devices. b) Electric-field dependence ...
Figure 7: a) Schematic energy diagram of OLED and organic materials used in the device. b) EL spectra at vari...
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
- -pot domino Pd-catalyzed Mizoroki–Heck–Buchwald–Hartwig synthesis of dibenzo[b,f]azepines. Dibenzo[b,f]thiapine and -oxepine synthesis via SNAr (thio)etherification, Wittig methylenation and Mizoroki–Heck reaction. A retrosynthetic pathway to dibenzo[b,f]oxepines via Ullmann coupling. Ullmann-type
- coupling in dibenzo[b,f]oxepine synthesis. Wittig reaction and Ullmann coupling as key steps in dihydrobenz[b,f]oxepine synthesis. Pd-catalysed dibenzo[b,f]azepine synthesis via norbornene azepine intermediate 109. A simple representation of olefin metathesis resulting in transalkylidenation. Ring-closing
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.
Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities
- Jorge de Lima Neto and
- Paulo Henrique Menezes
Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31
- Boger´s protocol, compound 58 was then subjected to an Ullmann coupling reaction in the presence of ester 59 to yield the corresponding diaryl ether 60. The hydrolysis of the ester followed by the removal of the benzyl group led to the corresponding seco-acid 62. The obtained compound showed high
- furnished the α,β-unsaturated ester 69. The subsequent catalytic hydrogenation led to the desired phenol 70 (Scheme 13) [44][45]. An Ullmann coupling reaction using compounds 66 and 70 gave the corresponding diaryl ether 71, which was submitted to an asymmetric dihydroxylation reaction using (DHQD)2PHAL to
- and the phosphonate 126 leading to the cis-ester 127 in high yield. Reduction of the ester using DIBAL gave the allylic alcohol 114 which was submitted to an Ullmann coupling [59] with isovanillin (80) to give the corresponding diaryl ether 128. Further esterification [60] with S-acetylthioacetic acid
Graphical Abstract
Figure 1: Structures of some members of the combretastatin D series, corniculatolides, and isocorniculatolide...
Scheme 1: Biosynthetic pathway proposed by Pettit and co-workers.
Scheme 2: Biosynthetic pathway towards corniculatolides or isocorniculatolides proposed by Ponnapalli and co-...
Scheme 3: Retrosynthetic approaches.
Scheme 4: Attempt of total synthesis of 2 by Boger and co-workers employing the Mitsunobu approach [27].
Scheme 5: Total synthesis of combretastatin D-2 (2) reported by Boger and co-workers employing an intramolecu...
Scheme 6: Formal synthesis of combretastatin D-2 (2) by Deshpande and co-workers using the Mitsunobu conditio...
Scheme 7: Total synthesis of combretastatin D-2 (2) by Rychnovsky and Hwang [36].
Scheme 8: Divergent synthesis of (±)-1 form combretastatin D-2 (2) by Rychnovsky and Hwang [36].
Scheme 9: Enantioselective synthesis of 1 by Rychnovsky and Hwang employing Jacobsen catalyst [41].
Scheme 10: Synthesis of fragment 57 by Couladouros and co-workers [43,45].
Scheme 11: Formal synthesis of compound 2 by Couladouros and co-workers [43,45].
Scheme 12: Synthesis of fragment 66 by Couladouros and co-workers [44,45].
Scheme 13: Synthesis of fragment 70 by Couladouros and co-workers [44,45].
Scheme 14: Synthesis of fragment 77 by Couladouros and co-workers [44,45].
Scheme 15: Synthesis of combretastatins 1 and 2 by Couladouros and co-workers [44,45].
Scheme 16: Formal synthesis of compound 2 by Gangakhedkar and co-workers [48].
Scheme 17: Synthesis of fragment 14 by Cousin and co-workers [50].
Scheme 18: Synthesis of fragment 91 by Cousin and co-workers [50].
Scheme 19: Formal synthesis of compound 2 by Cousin and co-workers [50].
Scheme 20: Synthesis of 2 diolide by Cousin and co-workers [50].
Scheme 21: Synthesis of combretastatin D-4 (4) by Nishiyama and co-workers [54].
Scheme 22: Synthesis of fragment 112 by Pettit and co-workers [55].
Scheme 23: Synthesis of fragment 114 by Pettit and co-workers [55].
Scheme 24: Attempt to the synthesis of compound 2 by Pettit and co-workers [55].
Scheme 25: Synthesis of combretastatin-D2 (2) starting from isovanilin (80) by Pettit and co-workers [55].
Scheme 26: Attempted synthesis of combretastatin-D2 (2) derivatives through an SNAr approach [55].
Scheme 27: Synthesis of combretastatin D-4 (4) by Pettit and co-workers [55].
Scheme 28: Synthesis of combretastatin D-2 (2) by Harras and co-workers [57].
Scheme 29: Synthesis of combretastatin D-4 (4) by Harras and co-workers [57].
Scheme 30: Formal synthesis of combretastatin D-1 (1) by Harras and co-workers [57].
Scheme 31: Synthesis of 11-O-methylcorniculatolide A (5) by Raut and co-workers [69].
Scheme 32: Synthesis of isocorniculatolide A (7) and O-methylated isocorniculatolide A 8 by Raut and co-worker...
Scheme 33: Synthesis of isocorniculatolide B (10) and hydroxyisocorniculatolide B 175 by Kim and co-workers [71].
Scheme 34: Synthesis of compound 9, 178, and 11 by Kim and co-workers [71].
Scheme 35: Synthesis of combretastatin D-2 prodrug salts [55].
Figure 2: ED50 values of the combretastatin D family against murine P388 lymphocytic leukemia cell line (appr...
Figure 3: IC50 of compounds against α-glucosidase [19].
Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation
- Ashish Kumar Mazumdar,
- Gyana Prakash Nanda,
- Nisha Yadav,
- Upasana Deori,
- Upasha Acharyya,
- Bahadur Sk and
- Pachaiyappan Rajamalli
Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122
- 'H-[9,3':6',9''-tercarbazol]-9'-yl)phenyl)(pyridin-4-yl)methanone (BPy-p3C) were synthesized via Ullmann coupling following the reported protocol [28]. These two TADF emitters have already been synthesized and device fabrication had been demonstrated. However, detailed photophysical investigations in
Graphical Abstract
Scheme 1: Synthetic schemes of BPy-pTC and BPy-p3C.
Figure 1: (a) Normalized absorption spectra of BPy-pTC and BPy-p3C in toluene at room temperature; (b) normal...
Figure 2: Transient photoluminescence decay (λex = 375 nm) of (a) BPy-pTC and (b) BPy-p3C in degassed THF (10...
Figure 3: AIEE studies: Emission spectra (λex = 375 nm, 10 µM) of (a) BPy-pTC and (d) BPy-p3C in THF with inc...
Figure 4: Normalized fluorescence at room temperature and phosphorescence spectra at 77 K (λex = 375 nm, 10 µ...
Figure 5: Transient photoluminescence decay (λex = 375 nm, 20 µM) of (a) BPy-pTC and (b) BPy-p3C aggregates i...
Figure 6: Fluorescence switching by acid and base fumes exposure: Emission spectra (λex = 375 nm) of (a) BPy-p...
Figure 7: Fluorescence intensity vs number of exposures for (a) BPy-p3C and (b) BPy-pTC thin films upon expos...
Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives
- Tülay Yıldız,
- İrem Baştaş and
- Hatice Başpınar Küçük
Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142
- , antitumor, antioxidant, and anticarcinogenic. Experimental General information The majority of the chemicals used in this work were commercially available from Merck or Aldrich. The starting compounds 1a–l were prepared by Ullmann coupling of 2-fluorobenzaldehyde and substituted phenols. Compounds 2a–l were
Graphical Abstract
Scheme 1: Synthesis of 4a: (i) phenol, K2CO3, DMF, reflux, 2 h, 91%; (ii) PhMgBr, dry THF, 0 °C, 2 h, 86%; (i...
Figure 1: Scope of substrates for intramolecular FCA by activation of 4a–l and their isolated yields. aCondit...
Scheme 2: Plausible reaction mechanism for the cyclization reaction of alkene 4a.
Synthetic accesses to biguanide compounds
- Oleksandr Grytsai,
- Cyril Ronco and
- Rachid Benhida
Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82
- catalysts in various organic reactions [1] such as the Ullmann coupling, Suzuki coupling, Suzuki–Miyaura coupling, and the Heck reaction. Aside from being useful synthetic agents, biguanides gained particular interest from the perspective of medicinal chemistry. For the first time, the biological activity
Graphical Abstract
Figure 1: Tautomeric forms of biguanide.
Figure 2: Illustrations of neutral, monoprotonated, and diprotonated structures biguanide.
Figure 3: The main approaches for the synthesis of biguanides. The core structure is obtained via the additio...
Scheme 1: The three main preparations of biguanides from cyanoguanidine.
Scheme 2: Synthesis of butylbiguanide using CuCl2 [16].
Scheme 3: Synthesis of biguanides by the direct fusion of cyanoguanidine and amine hydrochlorides [17,18].
Scheme 4: Synthesis of ethylbiguanide and phenylbiguanide as reported by Smolka and Friedreich [14].
Scheme 5: Synthesis of arylbiguanides through the reaction of cyanoguanidine with anilines in water [19].
Scheme 6: Synthesis of aryl- and alkylbiguanides by adaptations of Cohn’s procedure [20,21].
Scheme 7: Microwave-assisted synthesis of N1-aryl and -dialkylbiguanides [22,23].
Scheme 8: Synthesis of aryl- and alkylbiguanides by trimethylsilyl activation [24,26].
Scheme 9: Synthesis of phenformin analogs by TMSOTf activation [27].
Scheme 10: Synthesis of N1-(1,2,4-triazolyl)biguanides [28].
Scheme 11: Synthesis of 2-guanidinobenzazoles by addition of ortho-substituted anilines to cyanoguanidine [30,32] and...
Scheme 12: Synthesis of 2,4-diaminoquinazolines by the addition of 2-cyanoaniline to cyanoguanidine and from 3...
Scheme 13: Reactions of anthranilic acid and 2-mercaptobenzoic acid with cyanoguanidine [24,36,37].
Scheme 14: Synthesis of disubstituted biguanides with Cu(II) salts [38].
Scheme 15: Synthesis of an N1,N2,N5-trisubstituted biguanide by fusion of an amine hydrochloride and 2-cyano-1...
Scheme 16: Synthesis of N1,N5-disubstituted biguanides by the addition of anilines to cyanoguanidine derivativ...
Scheme 17: Microwave-assisted additions of piperazine and aniline hydrochloride to substituted cyanoguanidines ...
Scheme 18: Synthesis of N1,N5-alkyl-substituted biguanides by TMSOTf activation [27].
Scheme 19: Additions of oxoamines hydrochlorides to dimethylcyanoguanidine [49].
Scheme 20: Unexpected cyclization of pyridylcyanoguanidines under acidic conditions [50].
Scheme 21: Example of industrial synthesis of chlorhexidine [51].
Scheme 22: Synthesis of symmetrical N1,N5-diarylbiguanides from sodium dicyanamide [52,53].
Scheme 23: Synthesis of symmetrical N1,N5-dialkylbiguanides from sodium dicyanamide [54-56].
Scheme 24: Stepwise synthesis of unsymmetrical N1,N5-trisubstituted biguanides from sodium dicyanamide [57].
Scheme 25: Examples for the synthesis of unsymmetrical biguanides [58].
Scheme 26: Examples for the synthesis of an 1,3-diaminobenzoquinazoline derivative by the SEAr cyclization of ...
Scheme 27: Major isomers formed by the SEAr cyclization of symmetric biguanides derived from 2- and 3-aminophe...
Scheme 28: Lewis acid-catalyzed synthesis of 8H-pyrrolo[3,2-g]quinazoline-2,4-diamine [63].
Scheme 29: Synthesis of [1,2,4]oxadiazoles by the addition of hydroxylamine to dicyanamide [49,64].
Scheme 30: Principle of “bisamidine transfer” and analogy between the reactions with N-amidinopyrazole and N-a...
Scheme 31: Representative syntheses of N-amidino-amidinopyrazole hydrochloride [68,69].
Scheme 32: First examples of biguanide syntheses using N-amidino-amidinopyrazole [66].
Scheme 33: Example of “biguanidylation” of a hydrazide substrate [70].
Scheme 34: Example for the synthesis of biguanides using S-methylguanylisothiouronium iodide as “bisamidine tr...
Scheme 35: Synthesis of N-substituted N1-cyano-S-methylisothiourea precursors.
Scheme 36: Addition routes on N1-cyano-S-methylisothioureas.
Scheme 37: Synthesis of an hydroxybiguanidine from N1-cyano-S-methylisothiourea [77].
Scheme 38: Synthesis of an N1,N2,N3,N4,N5-pentaarylbiguanide from the corresponding triarylguanidine and carbo...
Scheme 39: Reactions of N,N,N’,N’-tetramethylguanidine (TMG) with carbodiimides to synthesize hexasubstituted ...
Scheme 40: Microwave-assisted addition of N,N,N’,N’-tetramethylguanidine to carbodiimides [80].
Scheme 41: Synthesis of N1-aryl heptasubstituted biguanides via a one-pot biguanide formation–copper-catalyzed ...
Scheme 42: Formation of 1,2-dihydro-1,3,5-triazine derivatives by the reaction of guanidine with excess carbod...
Scheme 43: Plausible mechanism for the spontaneous cyclization of triguanides [82].
Scheme 44: a) Formation of mono- and disubstituted (iso)melamine derivatives by the reaction of biguanides and...
Scheme 45: Reactions of 2-aminopyrimidine with carbodiimides to synthesize 2-guanidinopyrimidines as “biguanid...
Scheme 46: Non-catalyzed alternatives for the addition of 2-aminopyrimidine derivatives to carbodiimides. A) h...
Scheme 47: Addition of guanidinomagnesium halides to substituted cyanamides [90].
Scheme 48: Microwave-assisted synthesis of [11C]metformin by the reaction of 11C-labelled dimethylcyanamide an...
Scheme 49: Formation of 4-amino-6-dimethylamino[1,3,5]triazin-2-ol through the reaction of Boc-guanidine and d...
Scheme 50: Formation of 1,3,5-triazine derivatives via the addition of guanidines to substituted cyanamides [92].
Scheme 51: Synthesis of biguanide by the reaction of O-alkylisourea and guanidine [93].
Scheme 52: Aromatic nucleophilic substitution of guanidine on 2-O-ethyl-1,3,5-triazine [95].
Scheme 53: Synthesis of N1,N2-disubstituted biguanides by the reaction of guanidine and thioureas in the prese...
Scheme 54: Cyclization reactions involving condensations of guanidine(-like) structures with thioureas [97,98].
Scheme 55: Condensations of guanidine-like structures with thioureas [99,100].
Scheme 56: Condensations of guanidines with S-methylisothioureas [101,102].
Scheme 57: Addition of 2-amino-1,3-diazaaromatics to S-alkylisothioureas [103,104].
Scheme 58: Addition of guanidines to 2-(methylsulfonyl)pyrimidines [105].
Scheme 59: An example of a cyclodesulfurization reaction to a fused 3,5-diamino-1,2,4-triazole [106].
Scheme 60: Ring-opening reactions of 1,3-diaryl-2,4-bis(arylimino)-1,3-diazetidines [107].
Scheme 61: Formation of 3,5-diamino-1,2,4-triazole derivatives via addition of hydrazines to 1,3-diazetidine-2...
Scheme 62: Formation of a biguanide via the addition of aniline to 1,2,4-thiadiazol-3,5-diamines, ring opening...
Figure 4: Substitution pattern of biguanides accessible by synthetic pathways a–h.
Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186
- effective strategy for scalable synthesis of pristine sulfur, selenium and tellurium-doped sumanenes starting from 1,2-dichloro-3-nitrobenzene 200 by employing the Ullmann coupling and Sandmeyer reaction as key transformations (Scheme 49) [18][87][88]. The target was achieved starting from a three-fold
- Ullmann coupling reaction of 200 to produce the C3-symmetric trinitrotriphenylene 201. Having compound 201 in hand, the nitro groups were further converted into the corresponding amino groups via reduction in the presence of Pd/C under hydrogen gas atmosphere to furnish compound 202 in almost quantitative
Graphical Abstract
Figure 1: Representation of corannulene (1) and sumanene (2), the subunits of fullerene (C60).
Scheme 1: Mehta’s unsuccessful effort for the synthesis of sumanene scaffold 2.
Scheme 2: First synthesis of sumanene 2 by Sakurai et al. from norbornadiene 10.
Scheme 3: Synthesis of trimethylsumanene 28 from easily accessible norbornadiene (10).
Scheme 4: Generation of anions 29–31 and the preparation of tris(trimethylsilyl)sumanene 32.
Scheme 5: Synthesis of tri- and hexa-substituted sumanene derivatives.
Scheme 6: Synthesis of bowl-shaped π-extended sumanene derivatives 37a–f.
Scheme 7: Synthesis of monooxasumanene 38, trioxosumanene 40 along with imination of them.
Scheme 8: Synthesis of trimethylsumanenetrione 46 and exo-functionalized products 45a,b.
Scheme 9: Synthesis of bisumanenylidene 47 and sumanene dimer 48 from 2.
Scheme 10: The mono-substitution of 2 to generate diverse mono-sumanene derivatives 49a–d.
Scheme 11: Synthesis of sumanene building block 53 useful for further extension.
Scheme 12: Synthesis of hexafluorosumanene derivative 55 by Sakurai and co-workers.
Scheme 13: Preparation of sumanene-based carbene 60 and its reaction with cyclohexane.
Scheme 14: Barton–Kellogg reaction for the synthesis of sterically hindered alkenes.
Scheme 15: Synthesis of hydroxysumanene 68 by employing Baeyer–Villiger oxidation.
Scheme 16: Synthesis of sumanene derivatives having functionality at an internal carbon.
Scheme 17: Mechanism for nucleophilic substitution reaction at the internal carbon.
Scheme 18: Synthesis of diverse monosubstituted sumanene derivatives.
Scheme 19: Synthesis of di- and trisubstituted sumanene derivatives from sumanene (2).
Scheme 20: Preparation of monochlorosumanene 88 and hydrogenation of sumanene (2).
Scheme 21: The dimer 90 and bissumanenyl 92 achieved from halosumannes.
Scheme 22: Pyrenylsumanene 93 involving the Suzuki-coupling as a key transformation.
Scheme 23: Synthesis of various hexaarylsumanene derivatives using the Suzuki-coupling reaction.
Scheme 24: Synthesis of hexasubstituted sumanene derivatives 96 and 97.
Scheme 25: Synthesis of thioalkylsumanenes via an aromatic nucleophilic substitution reaction.
Scheme 26: Synthesis of tris(ethoxycarbonylethenyl)sumanene derivative 108.
Scheme 27: Synthesis of ferrocenyl-based sumanene derivatives.
Scheme 28: Synthesis of sumanenylferrocene architectures 118 and 119 via Negishi coupling.
Scheme 29: Diosmylation and the synthesis of phenylboronate ester 121 of sumanene.
Scheme 30: Synthesis of the iron-complex of sumanene.
Scheme 31: Synthesis of tri- and mononuclear sumanenyl zirconocene complexes.
Scheme 32: Synthesis of [CpRu(η6-sumanene)]PF6.
Scheme 33: Preparation of sumanene-based porous coordination networks 127 (spherical tetramer units) and 128 (...
Scheme 34: Synthesis of sumanenylhafnocene complexes 129 and 130.
Scheme 35: Synthesis of 134 and 135 along with PdII coordination complex 136.
Scheme 36: Synthesis of alkali metals sumanene complex K7(C21H102−)2(C21H93−)·8THF (137) containing di- and tr...
Scheme 37: The encapsulation of a Cs+ ion between two sumanenyl anions.
Scheme 38: Synthesis of monothiasumanene 140 and dithiasumanene 141 from 139.
Scheme 39: Synthesis of trithiasumanene 151 by Otsubo and his co-workers.
Scheme 40: Synthesis of trithiasumanene derivatives 155 and 156.
Scheme 41: Synthetic route towards hexathiolated trithiasumanenes 158.
Scheme 42: Synthesis of triselenasumanene 160 by Shao and teammates.
Scheme 43: Synthesis of tritellurasumanene derivatives from triphenylene skeletons.
Scheme 44: Synthesis of pyrazine-fused sumanene architectures through condensation reaction.
Scheme 45: Treatment of the trichalcogenasumanenes with diverse oxidative reagents.
Scheme 46: Ring-opening reaction with H2O2 and oxone of heterasumanenes 178 and 179.
Scheme 47: Synthesis of polycyclic compounds from sumanene derivatives.
Scheme 48: Synthesis of diimide-based heterocycles reported by Shao’s and co-workers.
Scheme 49: Synthesis of pristine trichalcogenasumanenes, 151, 205, and 206.
Scheme 50: Synthesis of trichalcogenasumanenes via hexaiodotriphenylene precursor 208.
Scheme 51: Synthesis of trisilasumanenes 214 and 215.
Scheme 52: Synthesis of trisilasumanene derivatives 218 and 219.
Scheme 53: Synthesis of novel trigermasumanene derivative 223.
Scheme 54: An attempt towards the synthesis of tristannasumanene derivative 228.
Scheme 55: Synthesis of triphosphasumanene trisulfide 232 from commercially available 229.
Scheme 56: The doping of sumanene derivatives with chalcogens (S, Se, Te) and phosphorus.
Scheme 57: Synthesis of heterasumanene containing three different heteroatoms.
Scheme 58: Synthesis of trichalcogenasumanene derivatives 240 and 179.
Scheme 59: Preparation of trichalcogenasumanenes 245 and 248.
Scheme 60: Design and synthesis of trichalcogenasumanene derivatives 252 and 178.
Scheme 61: Synthesis of spirosumanenes 264–269 and non-spiroheterasumanenes 258–263.
Scheme 62: Synthesis of sumanene-type hetero polycyclic compounds.
Scheme 63: Synthesis of triazasumanenes 288 and its sulfone congener 287.
Scheme 64: Synthesis of C3-symmetric chiral triaryltriazasumanenes via cross-coupling reaction.
Scheme 65: Synthesis of mononaphthosumanene 293 using Suzuki coupling as a key step.
Scheme 66: Synthesis of di- and trinaphthosumanene derivatives 302–304.
Scheme 67: Synthesis of hemifullerene skeletons by Hirao’s group.
Scheme 68: Design and construction of C70 fragment from a C60 sumanene fragment.
A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions
- Pezhman Shiri and
- Jasem Aboonajmi
Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52
- delivery [93], and cancer detection [94]. In this regard, various functionalized MNPs were employed in diverse organic reactions, including Suzuki–Miyaura reactions, Sonogashira reactions, Ullmann coupling, hydrogenation reactions, oxidation reactions, hydroformylation reactions, and “click” reactions [89
Graphical Abstract
Scheme 1: Chemical structure of the catalysts 1a and 1b and their catalytic application in CuAAC reactions.
Scheme 2: Synthetic route to the catalyst 11 and its catalytic application in CuAAC reactions.
Scheme 3: Synthetic route of dendrons, illustrated using G2-AMP 23.
Scheme 4: The catalytic application of CuYAu–Gx-AAA–SBA-15 in a CuAAC reaction.
Scheme 5: Synthetic route to the catalyst 36.
Scheme 6: Application of the catalyst 36 in CuAAC reactions.
Scheme 7: The synthetic route to the catalyst 45 and catalytic application of 45 in “click” reactions.
Scheme 8: Synthetic route to the catalyst 48 and catalytic application of 48 in “click” reactions.
Scheme 9: Synthetic route to the catalyst 58 and catalytic application of 58 in “click” reactions.
Scheme 10: Synthetic route to the catalyst 64 and catalytic application of 64 in “click” reactions.
Scheme 11: Chemical structure of the catalyst 68 and catalytic application of 68 in “click” reactions.
Scheme 12: Chemical structure of the catalyst 69 and catalytic application of 69 in “click” reactions.
Scheme 13: Synthetic route to, and chemical structure of the catalyst 74.
Scheme 14: Application of the cayalyst 74 in “click” reactions.
Scheme 15: Synthetic route to, and chemical structure of the catalyst 78 and catalytic application of 78 in “c...
Scheme 16: Synthetic route to the catalyst 85.
Scheme 17: Application of the catalyst 85 in “click” reactions.
Scheme 18: Synthetic route to the catalyst 87 and catalytic application of 87 in “click” reactions.
Scheme 19: Chemical structure of the catalyst 88 and catalytic application of 88 in “click” reactions.
Scheme 20: Synthetic route to the catalyst 90 and catalytic application of 90 in “click” reactions.
Scheme 21: Synthetic route to the catalyst 96 and catalytic application of 96 in “click” reactions.
Scheme 22: Synthetic route to the catalyst 100 and catalytic application of 100 in “click” reactions.
Scheme 23: Synthetic route to the catalyst 102 and catalytic application of 23 in “click” reactions.
Scheme 24: Synthetic route to the catalysts 108–111.
Scheme 25: Catalytic application of 108–111 in “click” reactions.
Scheme 26: Synthetic route to the catalyst 121 and catalytic application of 121 in “click” reactions.
Scheme 27: Synthetic route to 125 and application of 125 in “click” reactions.
Scheme 28: Synthetic route to the catalyst 131 and catalytic application of 131 in “click” reactions.
Scheme 29: Synthetic route to the catalyst 136.
Scheme 30: Application of the catalyst 136 in “click” reactions.
Scheme 31: Synthetic route to the catalyst 141 and catalytic application of 141 in “click” reactions.
Scheme 32: Synthetic route to the catalyst 144 and catalytic application of 144 in “click” reactions.
Scheme 33: Synthetic route to the catalyst 149 and catalytic application of 149 in “click” reactions.
Scheme 34: Synthetic route to the catalyst 153 and catalytic application of 153 in “click” reactions.
Scheme 35: Synthetic route to the catalyst 155 and catalytic application of 155 in “click” reactions.
Scheme 36: Synthetic route to the catalyst 157 and catalytic application of 157 in “click” reactions.
Scheme 37: Synthetic route to the catalyst 162.
Scheme 38: Application of the catalyst 162 in “click” reactions.
Scheme 39: Synthetic route to the catalyst 167 and catalytic application of 167 in “click” reactions.
Scheme 40: Synthetic route to the catalyst 169 and catalytic application of 169 in “click” reactions.
Scheme 41: Synthetic route to the catalyst 172.
Scheme 42: Application of the catalyst 172 in “click” reactions.
Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids
- László Orha,
- József M. Tukacs,
- László Kollár and
- László T. Mika
Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284
- excluding the copper impurities assisted Ullmann-coupling reactions. When 2-chloro-5-iodopyridine (1l) was reacted with 1 equiv of 2, 2-chloro-5-(2-phenylethynyl)pyridine (3l) was isolated as product with a yield of 72%. By the use of 2.5 equiv of 2, the chloro group also undergoes a coupling reaction to
Graphical Abstract
Scheme 1: Palladium-catalyzed Sonogashira cross-coupling of iodobenzene (1a) and phenylacetylene (2a) in ioni...
Figure 1: Effect of catalyst precursors used in Sonogashira coupling reaction of iodobenzene (1a, 0.5 mmol) a...
Figure 2: Re-use of Pd catalyst for Sonogashira coupling of iodobenzene (1a) and phenylacetylene (2a). Reacti...
Attempted synthesis of a meta-metalated calix[4]arene
- Christopher D. Jurisch and
- Gareth E. Arnott
Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195
- Ullmann-coupling to give monoazide 7. Synthesis of monoazidocalix[4]arene 7 under optimized conditions. Synthesis of the putative calix[4]arene mesoionic carbene ruthenium complex 13. Optimization results for the mononitration of calix[4]arene 9. Supporting Information Supporting Information File 392
Graphical Abstract
Figure 1: Inherent chirality generated by meta-substitution – the two structures are non-superposable mirror ...
Figure 2: General approach by Albrecht for MIC directed cyclometalation via C–H activation; M = Ru(II), Ir(II...
Figure 3: Concept of cyclometalated calix[4]arene target.
Scheme 1: Synthesis of model mesoionic carbene 5.
Scheme 2: Attempted Ullmann-coupling to give monoazide 7.
Scheme 3: Synthesis of monoazidocalix[4]arene 7 under optimized conditions.
Scheme 4: Synthesis of the putative calix[4]arene mesoionic carbene ruthenium complex 13.
Figure 4: High-resolution mass spectrum (ESI+) of putative ruthenacycle calix[4]arene 13.
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
- mechanisms, i.e., a Chan–Lam coupling and an Ullmann coupling. The Chan–Lam coupling involved a C–N bond formation (intermediate I, 84) which then entered into the Ullmann coupling to undergo intramolecular cyclization to form final product 78 and release Cu(III) to Cu(I) by reductive elimination. In this
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.
D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation
- Michael R. Imrich,
- Jochen Kraft,
- Cäcilia Maichle-Mössmer and
- Thomas Ziegler
Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182
- ligands are prepared in two steps from readily available 1,2-O-isopropylidene protected β-D-fructopyranoses by the BF3·OEt2-promoted Ritter reaction with 2-bromobenzonitrile to construct the oxazoline moiety followed by Ullmann coupling of the resulting aryl bromides with diphenylphosphine. Both steps
- proceeded mostly in good to high yields (57–86% for the Ritter reaction and 35–89% for the Ullmann coupling). The Ritter reaction gave two anomers, which could be separated by column chromatography. The prepared ligands showed promising results (er of up to 84:16) in Tsuji–Trost reactions with diphenylallyl
- acetate as model substrate. Keywords: Fürst–Plattner rule; oxazoline; Ritter reaction; Tsuji–Trost reaction; Ullmann coupling; Introduction The vast majority of biologically active compounds like vitamins and natural products occur as single enantiomers in nature. Usually only one enantiomer generates
Graphical Abstract
Figure 1: General structure of PHOX ligands 1 and structures of annulated glucosamine-based PHOX and PyOx lig...
Scheme 1: Preparation of 1,2-isopropylidene-protected D-fructose derivatives with different substitution patt...
Scheme 2: Activation of 7 to oxocarbenium ion 9 in the Ritter reaction.
Scheme 3: Zemplén deacetylation of 10i.
Figure 2: Molecular structure of 10j. Ellipsoids are given at the 50% probability level. Grey = carbon, red =...
Scheme 4: Benzylation of 10j to give 10b.
Scheme 5: Plausible mechanism of the Ritter reaction. For better clarity C-2 is not shown in conformers 9a an...
Scheme 6: Neighboring group participation of ester protective groups. For better clarity C-2 is not shown in ...
Scheme 7: Pd catalyzed Tsuji–Trost reation. BSA: N,O-bis(trimethylsilyl)acetamide, DMM: dimethyl malonate.
New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties
- Daria G. Selivanova,
- Alexei A. Gorbunov,
- Olga A. Mayorova,
- Alexander N. Vasyanin,
- Igor V. Lunegov,
- Elena V. Shklyaeva and
- Georgii G. Abashev
Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158
- ], Ullmann coupling [13][14], Buchwald–Hartwig amination [15] or N-alkylation of carbazole in the presence of alkali metal carbonates under MW irradiation [16]. In our case, the N-arylation was realized under phase transfer conditions using triethylbenzylammonium chloride (TEBA) as a catalyst [17][18
Graphical Abstract
Scheme 1: Synthesis of 9-[ω-(methoxyphenoxy)alkyl]-9H-carbazoles 1a,b.
Scheme 2: Synthesis of 9-[ω-(4-methoxyphenoxy)alkyl]-9H-carbazole-3-carbaldehydes 2a,b and 1-(5-arylthiophen-...
Scheme 3: Synthesis of quadrupolar chromophores 6a,b−8a,b.
Figure 1: Comparison of UV–vis absorption and fluorescence spectra of compounds 2a–5a (a) and 2b–5b (b) in CH...
Figure 2: Comparison of UV–vis absorption and fluorescence spectra of compounds 6a (a, b), 6b (c, d) in vario...
Figure 3: Comparison of UV–vis absorption and fluorescence spectra of compounds 7a (a, b) and 7b (c, d) in va...
Figure 4: Correlation between Kamlet–Taft π* parameters [29] and the absorption and emission maxima wavelength of...
Figure 5: Comparison of UV–vis absorption spectra of 2-amino-4,6-di(4-bromophenyl)pyrimidine and 2-amino-4-[4...
Figure 6: UV–vis absorption and fluorescence spectra of compounds 8a (a), 8b ( b) in CHCl3 (c = 10−4 mol L−1)....
Figure 7: Cyclic voltammograms of compounds 2b (a), 5b (b); WE – carbon-pyroceramic electrode, 10 cycles, Et4...
Figure 8: Cyclic voltammograms of compounds 6b (a), 7b (b), 8b (с); WE – carbon-pyroceramic electrode, 10 cyc...
Recent advances in copper-catalyzed asymmetric coupling reactions
- Fengtao Zhou and
- Qian Cai
Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280
- coupling The biaryl motif is a key subunit in many natural products and axially chiral ligands. The classical Ullmann coupling is one of the most important methods for the practical synthesis of biaryls [14]. However, only few reports of an asymmetric version of the Ullmann coupling have been documented
- . The first attempt of an intermolecular asymmetric Ullmann coupling for the formation of biaryls was reported by Miyano and co-workers in 1980. The authors used a chiral ester group as auxiliary but only poor diastereoselectivity (13% de) was obtained [15]. A few years later, the same group took
- -iodo-3,4,5-trimethoxybenzoyl substituents (Scheme 2). In 2006, Keay et al. [21] successfully developed an intramolecular asymmetric Ullmann coupling for the preparation of 3,3’-disubsituted MeO-BIPHEP derivatives using a chiral ester auxiliary that was easily prepared from (R)-2-hydroxy-3,3
Graphical Abstract
Scheme 1: Copper-catalyzed asymmetric preparation of biaryl diacids by Ullmann coupling.
Scheme 2: Intramolecular biaryl coupling of bis(iodotrimethoxybenzoyl)hexopyranose derivatives.
Scheme 3: Preparation of 3,3’-disubstituted MeO-BIPHEP derivatives.
Scheme 4: Enantioselective synthesis of trans-4,5,9,10-tetrahydroxy-9,10-dihydrophenanthrene.
Scheme 5: Copper-catalyzed coupling of oxazoline-substituted aromatics to afford biaryl products with high di...
Scheme 6: Total synthesis of O-permethyl-tellimagrandin I.
Scheme 7: Total synthesis of (+)-gossypol.
Scheme 8: Total synthesis of (−)-mastigophorene A.
Scheme 9: Total synthesis of isokotanin.
Scheme 10: Synthesis of dimethyl[7]thiaheterohelicenes.
Scheme 11: Intramolecular coupling with chiral ortho-substituents.
Scheme 12: Chiral 1,3-diol-derived tethers in the diastereoselective synthesis of biaryl compounds.
Scheme 13: Synthesis of chiral unsymmetrically substituted biaryl compounds.
Scheme 14: Atroposelective synthesis of biaryl ligands and natural products by using a chiral diether linker.
Scheme 15: Enantioselective arylation reactions of 2-methylacetoacetates.
Scheme 16: Asymmetric aryl C–N coupling reactions following a desymmetrization strategy.
Scheme 17: Construction of cyano-bearing all-carbon quaternary stereocenters.
Scheme 18: An unexpected inversion of the enantioselectivity in the asymmetric C–N coupling reactions using ch...
Scheme 19: Differentiation of two nucleophilic amide groups.
Scheme 20: Synthesis of spirobilactams through a double N-arylation reaction.
Scheme 21: Asymmetric N-arylation through kinetic resolution.
Scheme 22: Formation of cyano-substituted quaternary stereocenters through kinetic resolution.
Scheme 23: Copper-catalyzed intramolecular desymmetric aryl C–O coupling.
Scheme 24: Transition metal-catalyzed allylic substitutions.
Scheme 25: Copper-catalyzed asymmetric allylic substitution of allyl phosphates.
Scheme 26: Allylic substitution of allyl phosphates with allenylboronates.
Scheme 27: Allylic substitution of allyl phosphates with vinylboron.
Scheme 28: Allylic substitution of allyl phosphates with vinylboron.
Scheme 29: Construction of quaternary stereogenic carbon centers through enantioselective allylic cross-coupli...
Scheme 30: Cu-catalyzed enantioselective allyl–allyl cross-coupling.
Scheme 31: Cu-catalyzed enantioselective allylic substitutions with silylboronates.
Scheme 32: Asymmetric allylic substitution of allyl phosphates with silylboronates.
Scheme 33: Stereoconvergent synthesis of chiral allylboronates.
Scheme 34: Enantioselective allylic substitutions with diboronates.
Scheme 35: Enantioselective allylic alkylations of terminal alkynes.
The chemistry of isoindole natural products
- Klaus Speck and
- Thomas Magauer
Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243
- ][125][126][127]. The approach carried out by Castedo relied on 3-hydroxysarcocapnine (147), which could either be isolated from natural sources or prepared via an Ullmann coupling of a 1-(2-bromobenzyl)-8-hydroxyisoquinoline derivative [121][125]. Oxidation of 147 with 2,3-dichloro-5,6-dicyano-1,4
- copper(II) triflate-catalyzed Ullmann coupling furnished 136. Meroterpenoids: The term meroterpenoids describes a family of natural products with a mixed biosynthetic origin, partially derived from terpenoids and polyketides [129]. Several members of this class containing an isoindolinone motif, for
Graphical Abstract
Figure 1: a) Structural features and b) selected examples of non-natural congeners.
Scheme 1: Synthesis of isoindole 18.
Scheme 2: Staining amines with 1,4-diketone 19 (R = H).
Figure 2: Representative members of the indolocarbazole alkaloid family.
Figure 3: Staurosporine (26) bound to the adenosine-binding pocket [19] (from pdb1stc).
Figure 4: Structure of imatinib (34) and midostaurin (35).
Scheme 3: Biosynthesis of staurosporine (26).
Scheme 4: Wood’s synthesis of K-252a via the common intermediate 48.
Scheme 5: Synthesis of 26, 27, 49 and 50 diverging from the common intermediate 48.
Figure 5: Selected members of the cytochalasan alkaloid family.
Scheme 6: Biosynthesis of chaetoglobosin A (57) [56].
Scheme 7: Synthesis of cytochalasin D (70) by Thomas [63].
Scheme 8: Synthesis of L-696,474 (78).
Scheme 9: Synthesis of aldehyde 85 (R = TBDPS).
Scheme 10: Synthesis of (+)-aspergillin PZ (79) by Tanis.
Figure 6: Representative Berberis alkaloids.
Scheme 11: Proposed biosynthetic pathway to chilenine (93).
Scheme 12: Synthesis of magallanesine (97) by Danishefsky [84].
Scheme 13: Kurihara’s synthesis of magallanesine (85).
Scheme 14: Proposed biosynthesis of 113, 117 and 125.
Scheme 15: DNA lesion caused by aristolochic acid I (117) [102].
Scheme 16: Snieckus’ synthesis of piperolactam C (131).
Scheme 17: Synthesis of aristolactam BII (104).
Figure 7: Representative cularine alkaloids.
Scheme 18: Proposed biosynthesis of 136.
Scheme 19: The syntheses of 136 and 137 reported by Castedo and Suau.
Scheme 20: Synthesis of 136 by Couture.
Figure 8: Representative isoindolinone meroterpenoids.
Scheme 21: Postulated biosynthetic pathway for the formation of 156 (adopted from George) [143].
Scheme 22: Synthesis of stachyflin (156) by Katoh [144].
Figure 9: Selected examples of spirodihydrobenzofuranlactams.
Scheme 23: Synthesis of stachybotrylactam I (157).
Scheme 24: Synthesis of pestalachloride A (193) by Schmalz.
Scheme 25: Proposed mechanism for the BF3-catalyzed metal-free carbonyl–olefin metathesis [149].
Scheme 26: Preparation of the isoindoline core of muironolide A (204).
Scheme 27: Proposed biosynthesis of 208.
Scheme 28: Model for the biosynthesis of 215 and 217.
Scheme 29: Synthesis of lactonamycin (215) and lactonamycin Z (217).
Figure 10: Hetisine alkaloids 225–228.
Scheme 30: Biosynthetic proposal for the formation of the hetisine core [167].
Scheme 31: Synthesis of nominine (225).
Screening of ligands for the Ullmann synthesis of electron-rich diaryl ethers
- Nicola Otto and
- Till Opatz
Beilstein J. Org. Chem. 2012, 8, 1105–1111, doi:10.3762/bjoc.8.122
- is still challenging. For the synthesis of alkaloids containing the diaryl ether linkage, we searched for efficient ligands for the Ullmann coupling of electron-rich aryl bromides as the substrates and performed a ligand screening using the model system 4-bromoanisole/4-methoxyphenol. To the best of
Graphical Abstract
Figure 1: Selected examples of bioactive natural diaryl ethers.
Figure 2: Ligands that were subjected to the ligand screening.
Figure 3: Conversions of the model reaction versus the ligand numbers. For structures of the ligands refer to ...
Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors
- Chao Che,
- Song Li,
- Bo Yang,
- Shengchang Xin,
- Zhixiong Yu,
- Taofeng Shao,
- Chuanye Tao,
- Shuo Lin and
- Zhen Yang
Beilstein J. Org. Chem. 2012, 8, 841–849, doi:10.3762/bjoc.8.94
- cyclization with acetamidine to give 16. Compound 11g could be installed in single step by Ullmann coupling of 17 with 4-bromopyridine, in good yield. Substituent-modifications on the motif C In the third round of structural modifications, chemical diversity was explored by varying the nature of the
- type of structure. 19a–d were prepared through Suzuki coupling as described above, and 19e–g were obtained in 70–85% yield by Ullmann coupling of 3-bromobenzaldehyde with an excess of the appropriate amines 20e–g [49]. The Buchwald coupling of protected 3-bromobenzaldehyde with amines 20h–j proceeded
Graphical Abstract
Figure 1: Structures of Smo antagonists and agonists.
Scheme 1: General synthetic route for Sant-75. Reagents and conditions: (a) Pd(PPh3)4, PhMe, Na2CO3, H2O, 85 ...
Scheme 2: Substituent-modifications on the motif A. Reagents and conditions: (a) CH2Cl2, Et3N; (b) CH2Cl2, TF...
Scheme 3: Substituent-modifications on the motif A. Reagents and conditions: (a) (i) FeCl3, Zn, H2O, DMF, 100...
Scheme 4: Core modification on the motif A. Reagents and conditions: (a) BOP, DIEA, DMF; (b) CH2Cl2, TFA.
Figure 2: Core modification on the motif B.
Scheme 5: Synthesis of key intermediate biaryl aldehydes. Reagents and conditions: (a) Pd(OAc)2, PPh3, 1,4-di...
Scheme 6: Chemical modifications on the motif C. Reagents and conditions: (a) Pd(OAc)2, PPh3, 1,4-dioxane, Na2...
Scheme 7: Chemical modifications on the motif D. Reagents and conditions: (a) R2COCl, CH2Cl2.
Efficient and improved synthesis of Telmisartan
- A. Sanjeev Kumar,
- Samir Ghosh and
- G. N. Mehta
Beilstein J. Org. Chem. 2010, 6, No. 25, doi:10.3762/bjoc.6.25
- in the final step [6]. However, the main shortcomings of the synthesis remained, namely, the unsatisfactory regioselectivity in the alkylation of 8 with 4 and the intricate synthesis of the biaryl intermediate 7. In the original protocol, the latter was synthesized via an Ullmann coupling of the aryl
Graphical Abstract
Figure 1: The angiotensin II receptor antagonist Telmisartan.
Scheme 1: First literature synthesis of Telmisartan (a) nPrCOCl, C6H5Cl, 100 °C (b) HNO3/H2SO4, 0 °C (c) Pd/C...
Scheme 2: (a) Pd(PPh3)4, aq Na2CO3, THF, 12.0 h, 90%.
Scheme 3: (a) p-TsOH, toluene, 110 °C, 12 h, (b) Pd/C, 7 bar H2, MeOH, 60 °C, 24 h, 100% (c) AcOH, 120 °C, 2 ...
