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Search for "transition-metal catalysts" in Full Text gives 102 result(s) in Beilstein Journal of Organic Chemistry.
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
- organometallic chemistry and using transition metal catalysts, which need expensive and toxic chemicals. With the increasing interest in these methods, new organocatalysts and reagents that are less toxic, easier to use, readily accessible, and cheap have been developed [37]. In particular, the synthesis of
- arenes using the FCA methods with π-activated alcohols and organocatalysts has begun to be preferred over using conventional reagents, such as organohalogens and transition metal catalysts, which are toxic and require working under harsher conditions [38]. After these developments, the intramolecular FCA
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.
Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account
- Ranadeep Talukdar
Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137
- with 5-iodoindole (182) in the presence of thiourea and a recyclable CuO nanoparticle catalyst (Scheme 26) [116]. This heterogeneous catalysis strategy bypasses the use of unpleasant aryl thiols, which are generally coupled with other aryl halides in the presence of transition-metal catalysts for
Graphical Abstract
Scheme 1: Synthesis of 2,2’-bis(indole)borinic ester 3.
Scheme 2: Synthesis of 2,2’-bisindole NHC·boranes by an SEAr mechanism.
Scheme 3: Syntheses of indolyl amines through Buchwald–Hartwig cross coupling.
Scheme 4: Synthesis of 3,3’-bis(indolyl) ethers.
Scheme 5: C–H silylation of indoles.
Scheme 6: n-BuLi-mediated syntheses of bis(indol-3-yl)silanes.
Scheme 7: Acid-catalyzed syntheses of bis(indol-3-yl)silanes and mechanisms.
Scheme 8: B(C6F5)3 and Al(C6F5)3-catalyzed syntheses of bis(indol-3-yl)silanes reported by Han.
Scheme 9: Base-mediated syntheses of bis and tris(indol-2-yl)phosphines.
Scheme 10: Synthesis of bis(indol-2-yl)sulfides using SL2-type reagents.
Scheme 11: Synthesis of 2,3’- and 2,2’-bis(indolyl)sulfides using disulfides as substrates.
Scheme 12: Synthesis of diindol-2-ylsulfide (84) from 2-iodoindole (92) and thiourea.
Scheme 13: Synthesis of bis(indol-3-yl)sulfides using N-silylated 3-bromoindole 93.
Scheme 14: Fischer indole synthesis of bis(indol-3-yl)sulfides using thio diketones.
Scheme 15: Oxidative synthesis of bis(indol-3-yl)sulfides using indoles and elemental sulfur.
Scheme 16: Synthesis of bis(indol-3-yl)sulfides using sulfoxides as sulfur source.
Scheme 17: Syntheses of bis(indol-2-yl)selanes.
Scheme 18: Syntheses of bis(indol-3-yl)selanes.
Scheme 19: Synthesis of bis(indol-2-yl)tellane 147.
Scheme 20: Synthesis of tris(indolyl)borane 154.
Scheme 21: Synthesis of bis(indol-4-yl)amines 159.
Scheme 22: Synthesis of bis(indol-5-yl)amines.
Scheme 23: Synthesis of 6,5’/6,6’-bis(indolyl)amines.
Scheme 24: Synthesis of potent HIV-inhibitors 6,6’-bis(indolyl) ethers.
Scheme 25: Synthesis of bis(indol-7-yl) ether.
Scheme 26: Synthesis of di(indol-5-yl)sulfide (183).
Scheme 27: Syntheses of 2,2’-diformyl-7,7’-bis(indolyl)selenides.
Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs
- Jongwoo Son
Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122
- [49]. To date, there are several examples of late-stage C–H amination methods that utilize iron and manganese as 3d transition metal catalysts [50][51][52]. However, intermolecular benzylic C–H amination has rarely been explored due to the challenges associated with selectivity and reactivity. In 2018
Graphical Abstract
Scheme 1: Mn-catalyzed late-stage fluorination of sclareolide (1) and complex steroid 3.
Figure 1: Proposed reaction mechanism of C–H fluorination by a manganese porphyrin catalyst.
Scheme 2: Late-stage radiofluorination of biologically active complex molecules.
Figure 2: Proposed mechanism of C–H radiofluorination.
Scheme 3: Late-stage C–H azidation of bioactive molecules. a1.5 mol % of Mn(TMP)Cl (5) was used. bMethyl acet...
Figure 3: Proposed reaction mechanism of manganese-catalyzed C–H azidation.
Scheme 4: Mn-catalyzed late-stage C–H azidation of bioactive molecules via electrophotocatalysis. a2.5 mol % ...
Figure 4: Proposed reaction mechanism of electrophotocatalytic azidation.
Scheme 5: Manganaelectro-catalyzed late-stage azidation of bioactive molecules.
Figure 5: Proposed reaction pathway of manganaelectro-catalyzed late-stage C–H azidation.
Scheme 6: Mn-catalyzed late-stage amination of bioactive molecules. a3 Å MS were used. Protonation with HBF4⋅...
Figure 6: Proposed mechanism of manganese-catalyzed C–H amination.
Scheme 7: Mn-catalyzed C–H methylation of heterocyclic scaffolds commonly found in small-molecule drugs. aDAS...
Scheme 8: Examples of late-stage C–H methylation of bioactive molecules. aDAST activation. bFor insoluble sub...
Scheme 9: A) Mn-catalyzed late-stage C–H alkynylation of peptides. B) Intramolecular late-stage alkynylative ...
Figure 7: Proposed reaction mechanism of Mn(I)-catalyzed C–H alkynylation.
Scheme 10: Late-stage Mn-catalyzed C–H allylation of peptides and bioactive motifs.
Scheme 11: Intramolecular C–H allylative cyclic peptide formation.
Scheme 12: Late-stage C–H glycosylation of tryptophan analogues.
Scheme 13: Late-stage C–H glycosylation of tryptophan-containing peptides.
Scheme 14: Late-stage C–H alkenylation of tryptophan-containing peptides.
Scheme 15: A) Late-stage C–H macrocyclization of tryptophan-containing peptides and B) traceless removal of py...
Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones
- Girish Suresh Yedase,
- Sumit Kumar,
- Jessica Stahl,
- Burkhard König and
- Veera Reddy Yatham
Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121
- reported methods require either specific nanoparticle catalysts [39][40][41][42] or the catalytic method is limited to electron-rich or electron-neutral benzylic alcohols [56]. An operationally simple method avoiding waste and potentially toxic transition-metal catalysts that is able to convert any
Graphical Abstract
Scheme 1: Photocatalyzed aerobic oxidation of aromatic alcohols.
Scheme 2: Substrate scope. Reaction conditions as given in Table 1 (entry 1). Yields are isolated yields, average of...
Scheme 3: Selective oxidation of 3-bromobenzyl alcohol in the presence of 3-phenylpropanol. Compound 1af was ...
Figure 1: Mechanistic studies. (A): UV–vis spectra of the CeIV(OBn)Cln complex in CH3CN under blue light irra...
Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones
- Jan Bartáček,
- Jan Svoboda,
- Martin Kocúrik,
- Jaroslav Pochobradský,
- Alexander Čegan,
- Miloš Sedlák and
- Jiří Váňa
Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84
- successful transition-metal catalysts are those based on rhodium, as evidenced by the number of reports that deal with the issue. The rhodium-catalysed addition of various boronic acids to conjugated cyclic enones (the so-called Hayashi–Miyaura reaction) is a well-established method for 3-unsubstituted
Graphical Abstract
Scheme 1: Synthesis of optically pure 4-phenylchroman-2-one [34].
Scheme 2: Synthesis of (R)-tolterodine [3].
Scheme 3: Catalytic cycle of the Pd(II)-catalysed 1,4-addition of organoboron reagents to enones [3,26,35].
Scheme 4: Enantioselective β-arylation of cyclohexanone [38].
Scheme 5: Application of L2/Pd(OAc)2 in the total synthesis of terpenes [8].
Scheme 6: Plausible catalytic cycle for the addition of phenylboronic acid to 2-cyclohexenone catalysed by L3...
Scheme 7: Microwave-assisted addition of phenylboronic acid to 2-cyclohexenone catalysed by L4/Pd2(dba)3·CHCl3...
Scheme 8: Plausible catalytic cycle of the addition of phenylboronic acid to 2-cyclohexenone catalysed by pal...
Scheme 9: Proposed catalytic cycle for the addition of phenylboronic acids to 2-cyclohexenone catalysed by Pd...
Scheme 10: Usage of addition reactions of boronic acids to various chromones in the syntheses of potentially a...
Scheme 11: Multigram-scale synthesis of ABBV-2222 [6].
Scheme 12: Application of the asymmetric addition of phenylboronic acid to a chromone derivative for the total...
Scheme 13: Plausible catalytic cycle for the addition of phenylboronic acid to 3-methyl-2-cyclohexenone cataly...
Scheme 14: Total syntheses of naturally occurring terpenoids [10,11].
Scheme 15: Use of the L9/Pd(TFA)2 catalytic system for the synthesis of intermediates of biologically active c...
Scheme 16: Usage of a Michael addition catalysed by L9/Pd(TFA)2 in the total synthesis of (–)-ar-tenuifolene [12].
Scheme 17: Synthesis of terpenoids by Michael addition to 3-methyl-2-cyclopentenone [13].
Scheme 18: Rh-catalysed isomerisation of 3-alkyl-3-arylcyclopentanones to 1-tetralones [53].
Scheme 19: Addition reaction of phenylboronic acid to 3-methyl-2-cyclohexenone catalysed by L9/Pd(TFA)2 in wat...
Scheme 20: Micellar nanoreactor PdL10c for the synthesis of flavanones [58].
Scheme 21: Plausible catalytic cycle for the desymmetrisation of polycyclic cyclohexenediones by the addition ...
Scheme 22: Attempt to use the catalytic system L2/Pd(TFA)2 for the addition of phenylboronic acid to 3-methyl-...
Scheme 23: Ring opening of an enantioenriched tetrahydropyran-2-one derivative as alternative strategy to line...
Scheme 24: Synthesis of biologically active compounds from addition products [14-16].
Scheme 25: Chiral 1,10-phenantroline derivative L15 as ligand for the Pd-catalysed addition reactions of pheny...
Scheme 26: The Rh-catalysed addition reaction of phenylboronic acid to a 3-substituted enone [20].
Scheme 27: Underdeveloped methodologies [14,15,65-67].
Scheme 28: Flowchart for the selection of the proper catalytic system.
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
- the excited state, causing an electron transfer to give radicals and to initiate subsequent reactions. Besides light as an external energy source, reactions involving the participation of EDA complexes are mild, obviating transition metal catalysts or photosensitizers in the majority of cases and are
- synthesis has encouraged chemists to pursue more efficient methods to manufacture fine and usable chemicals [7]. The reactions that EDA complexes participate in have been shown to be an enormous success, mainly due to the fact that they obviate photoredox catalysts or transition metal catalysts in the vast
- -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.
Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles
- Soumyaranjan Pati,
- Renata G. Almeida,
- Eufrânio N. da Silva Júnior and
- Irishi N. N. Namboothiri
Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66
- leading to poor N1/N2 selectivity, for instance, in the direct N-alkylation of triazoles [21][22][23]. Despite these challenges, a number of N1- and N2-selective alkylation methods have been developed employing transition metal catalysts which include Au-catalysed desulfonylative coupling N-tosyl-1,2,3
Graphical Abstract
Scheme 1: Synthesis, functionalization and applications of triazoles.
Scheme 2: The reaction was performed using 0.2 mmol N-tosyl-1,2,3-triazole 1 and 0.2 mmol of cyclohexyl-1,3-d...
Scheme 3: Control experiments.
Scheme 4: Mechanistic proposal for the formation of β-triazolylenones.
Figure 1: Nucleophilic addition to 5- and 6-membered cyclic tosyloxyenones.
An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp3)–H bond functionalization under solvent- and catalyst-free conditions
- Divya Rohini Yennamaneni,
- Vasu Amrutham,
- Krishna Sai Gajula,
- Rammurthy Banothu,
- Murali Boosa and
- Narender Nama
Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259
- , green, and was carried out in a facile operative environment without using any hazardous transition metal catalysts or any other coupling reagents. Different aromatic aldehydes and azaarenes were monitored, and the yields of the resulting products were moderate to excellent. We accomplished several
Graphical Abstract
Scheme 1: Benzylic addition of aldehydes to azaarenes using different catalysts.
Scheme 2: Synthesis of azaarene derivatives from different precursors.
Scheme 3: Our work: catalyst- and solvent-free benzylic addition of aldehydes to azaarenes.
Scheme 4: Large-scale experiments for the synthesis of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (...
Scheme 5: Plausible mechanism for the formation of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (3a) ...
Silver-catalyzed synthesis of β-fluorovinylphosphonates by phosphonofluorination of aromatic alkynes
- Yajing Zhang,
- Qingshan Tian,
- Guozhu Zhang and
- Dayong Zhang
Beilstein J. Org. Chem. 2020, 16, 3086–3092, doi:10.3762/bjoc.16.258
- -fluorovinylphosphonates under mild conditions. First, we examined the catalytic activity of various transition metal catalysts, including Au, Ag, Cu, Rh, and Pd complexes (Supporting Information File 1). Among these metal salts, silver salts, especially AgOAc, were the most effective catalysts for generating the desired
Graphical Abstract
Scheme 1: Metal-catalyzed difunctionalization of unsaturated carbon–carbon bonds.
Scheme 2: Substrate scope for the synthesis of the β-fluorovinylphosphonates 2 using diethyl phosphite. React...
Scheme 3: Substrate scope for the synthesis of the β-fluorovinylphosphonates 3 using dimethyl phosphite. Reac...
Scheme 4: Radical-trapping experiments.
Scheme 5: Proposed mechanism for the silver-catalyzed phosphonofluorination of alkynes.
Scheme 6: Attempted use of a suspected phosphonofluorination intermediate to synthesize a β-fluorovinylphosph...
Recent developments in enantioselective photocatalysis
- Callum Prentice,
- James Morrisson,
- Andrew D. Smith and
- Eli Zysman-Colman
Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197
Graphical Abstract
Scheme 1: Amine/photoredox-catalysed α-alkylation of aldehydes with alkyl bromides bearing electron-withdrawi...
Scheme 2: Amine/HAT/photoredox-catalysed α-functionalisation of aldehydes using alkenes.
Scheme 3: Amine/cobalt/photoredox-catalysed α-functionalisation of ketones and THIQs.
Scheme 4: Amine/photoredox-catalysed α-functionalisation of aldehydes or ketones with imines. (a) Using keton...
Scheme 5: Bifunctional amine/photoredox-catalysed enantioselective α-functionalisation of aldehydes.
Scheme 6: Bifunctional amine/photoredox-catalysed α-functionalisation of aldehydes using amine catalysts via ...
Scheme 7: Amine/photoredox-catalysed RCA of iminium ion intermediates. (a) Synthesis of quaternary stereocent...
Scheme 8: Bifunctional amine/photoredox-catalysed RCA of enones in a radical chain reaction initiated by an i...
Scheme 9: Bifunctional amine/photoredox-catalysed RCA reactions of iminium ions with different radical precur...
Scheme 10: Bifunctional amine/photoredox-catalysed radical cascade reactions between enones and alkenes with a...
Scheme 11: Amine/photocatalysed photocycloadditions of iminium ion intermediates. (a) External photocatalyst u...
Scheme 12: Amine/photoredox-catalysed addition of acrolein (94) to iminium ions.
Scheme 13: Dual NHC/photoredox-catalysed acylation of THIQs.
Scheme 14: NHC/photocatalysed spirocyclisation via photoisomerisation of an extended Breslow intermediate.
Scheme 15: CPA/photoredox-catalysed aza-pinacol cyclisation.
Scheme 16: CPA/photoredox-catalysed Minisci-type reaction between azaarenes and α-amino radicals.
Scheme 17: CPA/photoredox-catalysed radical additions to azaarenes. (a) α-Amino radical or ketyl radical addit...
Scheme 18: CPA/photoredox-catalysed reduction of azaarene-derived substrates. (a) Reduction of ketones. (b) Ex...
Scheme 19: CPA/photoredox-catalysed radical coupling reactions of α-amino radicals with α-carbonyl radicals. (...
Scheme 20: CPA/photoredox-catalysed Povarov reaction.
Scheme 21: CPA/photoredox-catalysed reactions with imines. (a) Decarboxylative imine generation followed by Po...
Scheme 22: Bifunctional CPA/photocatalysed [2 + 2] photocycloadditions.
Scheme 23: PTC/photocatalysed oxygenation of 1-indanone-derived β-keto esters.
Scheme 24: PTC/photoredox-catalysed perfluoroalkylation of 1-indanone-derived β-keto esters via a radical chai...
Scheme 25: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 26: Bifunctional hydrogen bonding/photocatalysed intramolecular RCA cyclisation of a quinolone.
Scheme 27: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 28: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloaddition reactions. (a) First use of...
Scheme 29: Bifunctional hydrogen bonding/photocatalysed deracemisation of allenes.
Scheme 30: Bifunctional hydrogen bonding/photocatalysed deracemisation reactions. (a) Deracemisation of sulfox...
Scheme 31: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloaddition of coumarins....
Scheme 32: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloadditions of quinolones. (a) Intramo...
Scheme 33: Hydrogen bonding/photocatalysed formal arylation of benzofuranones.
Scheme 34: Hydrogen bonding/photoredox-catalysed dehalogenative protonation of α,α-chlorofluoro ketones.
Scheme 35: Hydrogen bonding/photoredox-catalysed reductions. (a) Reduction of 1,2-diketones. (b) Reduction of ...
Scheme 36: Hydrogen bonding/HAT/photocatalysed deracemisation of cyclic ureas.
Scheme 37: Hydrogen bonding/HAT/photoredox-catalysed synthesis of cyclic sulfonamides.
Scheme 38: Hydrogen bonding/photoredox-catalysed reaction between imines and indoles.
Scheme 39: Chiral cation/photoredox-catalysed radical coupling of two α-amino radicals.
Scheme 40: Chiral phosphate/photoredox-catalysed hydroetherfication of alkenols.
Scheme 41: Chiral phosphate/photoredox-catalysed synthesis of pyrroloindolines.
Scheme 42: Chiral anion/photoredox-catalysed radical cation Diels–Alder reaction.
Scheme 43: Lewis acid/photoredox-catalysed cycloadditions of carbonyls. (a) Formal [2 + 2] cycloaddition of en...
Scheme 44: Lewis acid/photoredox-catalysed RCA reaction using a scandium Lewis acid between α-amino radicals a...
Scheme 45: Lewis acid/photoredox-catalysed RCA reaction using a copper Lewis acid between α-amino radicals and...
Scheme 46: Lewis acid/photoredox-catalysed synthesis of 1,2-amino alcohols from aldehydes and nitrones using a...
Scheme 47: Lewis acid/photocatalysed [2 + 2] photocycloadditions of enones and alkenes.
Scheme 48: Meggers’s chiral-at-metal catalysts.
Scheme 49: Lewis acid/photoredox-catalysed α-functionalisation of ketones with alkyl bromides bearing electron...
Scheme 50: Bifunctional Lewis acid/photoredox-catalysed radical coupling reaction using α-chloroketones and α-...
Scheme 51: Lewis acid/photocatalysed RCA of enones. (a) Using aldehydes as acyl radical precursors. (b) Other ...
Scheme 52: Bifunctional Lewis acid/photocatalysis for a photocycloaddition of enones.
Scheme 53: Lewis acid/photoredox-catalysed RCA reactions of enones using DHPs as radical precursors.
Scheme 54: Lewis acid/photoredox-catalysed functionalisation of β-ketoesters. (a) Hydroxylation reaction catal...
Scheme 55: Bifunctional copper-photocatalysed alkylation of imines.
Scheme 56: Copper/photocatalysed alkylation of imines. (a) Bifunctional copper catalysis using α-silyl amines....
Scheme 57: Bifunctional Lewis acid/photocatalysed intramolecular [2 + 2] photocycloaddition.
Scheme 58: Bifunctional Lewis acid/photocatalysed [2 + 2] photocycloadditions (a) Intramolecular cycloaddition...
Scheme 59: Bifunctional Lewis acid/photocatalysed rearrangement of 2,4-dieneones.
Scheme 60: Lewis acid/photocatalysed [2 + 2] cycloadditions of cinnamate esters and styrenes.
Scheme 61: Nickel/photoredox-catalysed arylation of α-amino acids using aryl bromides.
Scheme 62: Nickel/photoredox catalysis. (a) Desymmetrisation of cyclic meso-anhydrides using benzyl trifluorob...
Scheme 63: Nickel/photoredox catalysis for the acyl-carbamoylation of alkenes with aldehydes using TBADT as a ...
Scheme 64: Bifunctional copper/photoredox-catalysed C–N coupling between α-chloro amides and carbazoles or ind...
Scheme 65: Bifunctional copper/photoredox-catalysed difunctionalisation of alkenes with alkynes and alkyl or a...
Scheme 66: Copper/photoredox-catalysed decarboxylative cyanation of benzyl phthalimide esters.
Scheme 67: Copper/photoredox-catalysed cyanation reactions using TMSCN. (a) Propargylic cyanation (b) Ring ope...
Scheme 68: Palladium/photoredox-catalysed allylic alkylation reactions. (a) Using alkyl DHPs as radical precur...
Scheme 69: Manganese/photoredox-catalysed epoxidation of terminal alkenes.
Scheme 70: Chromium/photoredox-catalysed allylation of aldehydes.
Scheme 71: Enzyme/photoredox-catalysed dehalogenation of halolactones.
Scheme 72: Enzyme/photoredox-catalysed dehalogenative cyclisation.
Scheme 73: Enzyme/photoredox-catalysed reduction of cyclic imines.
Scheme 74: Enzyme/photocatalysed enantioselective reduction of electron-deficient alkenes as mixtures of (E)/(Z...
Scheme 75: Enzyme/photoredox catalysis. (a) Deacetoxylation of cyclic ketones. (b) Reduction of heteroaromatic...
Scheme 76: Enzyme/photoredox-catalysed synthesis of indole-3-ones from 2-arylindoles.
Scheme 77: Enzyme/HAT/photoredox catalysis for the DKR of primary amines.
Scheme 78: Bifunctional enzyme/photoredox-catalysed benzylic C–H hydroxylation of trifluoromethylated arenes.
Et3N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties
- Dharmender Singh,
- Vipin Kumar and
- Virender Singh
Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146
- functional groups and aza-heterocyclic frameworks. However, organic transformations in which aromatic nitro groups act as leaving groups are less reported and require the use of transition-metal catalysts such as Cu, Rh, Pd, etc. [35][36][37]. Though, several elegant methods have been developed for the
Graphical Abstract
Figure 1: Representative examples of some commercial drugs and biologically active alkaloids.
Scheme 1: Synthesis of β-carboline-linked 2-nitrochalcones.
Scheme 2: Synthesis of β-carboline-linked benzothiophenone frameworks.
Scheme 3: Comparison of outcome of one-pot vs two-pot approach.
Scheme 4: One-pot synthesis of β-carboline C-1-tethered benzothiophenone derivatives.
Scheme 5: One-pot synthesis of β-carboline C-3-linked benzothiophenone derivatives.
Scheme 6: One-pot synthesis of β-carboline-linked benzothiophene derivative 6C.
Scheme 7: Control experiment in the presence of a radical scavenger.
Figure 2: Proposed reaction mechanism.
Figure 3: Fluorescence spectra of 2aA–nA, 2bB, 2hB, and 6C.
Figure 4: Fluorescence spectra of 4aA–gA, and 4eB.
Recent synthesis of thietanes
- Jiaxi Xu
Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116
- -haloalkyl)thiiranes with various nucleophiles, nucleophilic ring expansion of thiiranes with sulfur ylides, and the electrophilic ring expansion of thiiranes with carbenes generated from sulfur ylides under the catalysis of transition-metal catalysts. 4.1.1 Synthesis via nucleophilic ring expansion of 2-(1
Graphical Abstract
Figure 1: Examples of biologically active thietane-containing molecules.
Figure 2: The diverse methods for the synthesis of thietanes.
Scheme 1: Synthesis of 1-(thietan-2-yl)ethan-1-ol (10) from 3,5-dichloropentan-2-ol (9).
Scheme 2: Synthesis of thietanose nucleosides 2,14 from 2,2-bis(bromomethyl)propane-1,3-diol (11).
Scheme 3: Synthesis of methyl 3-vinylthietane-3-carboxylate (19).
Scheme 4: Synthesis of 1,6-thiazaspiro[3.3]heptane (24).
Scheme 5: Synthesis of 6-amino-2-thiaspiro[3.3]heptane hydrochloride (28).
Scheme 6: Synthesis of optically active thietane 31 from vitamin C.
Scheme 7: Synthesis of an optically active thietane nucleoside from diethyl L-tartrate (32).
Scheme 8: Synthesis of thietane-containing spironucleoside 40 from 5-aldo-3-O-benzyl-1,2-O-isopropylidene-α-D...
Scheme 9: Synthesis of optically active 2-methylthietane-containing spironucleoside 43.
Scheme 10: Synthesis of a double-linked thietane-containing spironucleoside 48.
Scheme 11: Synthesis of two diastereomeric thietanose nucleosides via 2,4-di(benzyloxymethyl)thietane (49).
Scheme 12: Synthesis of the thietane-containing PI3k inhibitor candidate 54.
Scheme 13: Synthesis of the spirothietane 57 as the key intermediate to Nuphar sesquiterpene thioalkaloids.
Scheme 14: Synthesis of spirothietane 61 through a direct cyclic thioetherification of 3-mercaptopropan-1-ol.
Scheme 15: Synthesis of thietanes 66 from 1,3-diols 62.
Scheme 16: Synthesis of thietanylbenzimidazolone 75 from (iodomethyl)thiazolobenzimidazole 70.
Scheme 17: Synthesis of 2-oxa-6-thiaspiro[3.3]heptane (80) from bis(chloromethyl)oxetane 76 and thiourea.
Scheme 18: Synthesis of the thietane-containing glycoside, 2-O-p-toluenesulfonyl-4,6-thioanhydro-α-D-gulopyran...
Scheme 19: Synthesis of methyl 4,6-thioanhydro-α-D-glucopyranoside (89).
Scheme 20: Synthesis of thietane-fused α-D-galactopyranoside 93.
Scheme 21: Synthesis of thietane-fused α-D-gulopyranoside 100.
Scheme 22: Synthesis of 3,5-anhydro-3-thiopentofuranosides 104.
Scheme 23: Synthesis of anhydro-thiohexofuranosides 110, 112 and 113 from from 1,2:4,5-di-O-isopropylidene D-f...
Scheme 24: Synthesis of optically active thietanose nucleosides from D- and L-xyloses.
Scheme 25: Synthesis of thietane-fused nucleosides.
Scheme 26: Synthesis of 3,5-anhydro-3-thiopentofuranosides.
Scheme 27: Synthesis of 2-amino-3,5-anhydro-3-thiofuranoside 141.
Scheme 28: Synthesis of thietane-3-ols 145 from (1-chloromethyl)oxiranes 142 and hydrogen sulfide.
Scheme 29: Synthesis of thietane-3-ol 145a from chloromethyloxirane (142a).
Scheme 30: Synthesis of thietane-3-ols 145 from 2-(1-haloalkyl)oxiranes 142 and 147 with ammonium monothiocarb...
Scheme 31: Synthesis of 7-deoxy-5(20)thiapaclitaxel 154a, a thietane derivative of taxoids.
Scheme 32: Synthesis of 5(20)-thiadocetaxel 158 from 10-deacetylbaccatin III (155).
Scheme 33: Synthesis of thietane derivatives 162 as precursors for deoxythiataxoid synthesis through oxiraneme...
Scheme 34: Synthesis of 7-deoxy 5(20)-thiadocetaxel 154b.
Scheme 35: Mechanism for the formation of the thietane ring in 171 from oxiranes with vicinal leaving groups 1...
Scheme 36: Synthesis of cis-2,3-disubstituted thietane 175 from thiirane-2-methanol 172.
Scheme 37: Synthesis of a bridged thietane 183 from aziridine cyclohexyl tosylate 179 and ammonium tetrathiomo...
Scheme 38: Synthesis of thietanes via the photochemical [2 + 2] cycloaddition of thiobenzophenone 184a with va...
Scheme 39: Synthesis of spirothietanes through the photo [2 + 2] cycloaddition of cyclic thiocarbonyls with ol...
Scheme 40: Photochemical synthesis of spirothietane-thioxanthenes 210 from thioxanthenethione (208) and butatr...
Scheme 41: Synthesis of thietanes 213 from 2,4,6-tri(tert-butyl)thiobenzaldehyde (211) with substituted allene...
Scheme 42: Photochemical synthesis of spirothietanes 216 and 217 from N-methylthiophthalimide (214) with olefi...
Scheme 43: Synthesis of fused thietanes from quadricyclane with thiocarbonyl derivatives 219.
Scheme 44: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-methyldithiosuccinimides ...
Scheme 45: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-methylthiosuccinimide/thi...
Scheme 46: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-alkylmonothiophthalimides...
Scheme 47: Synthesis of spirothietanes from dithiosuccinimides 223 with 2,3-dimethyl-2-butene (215a).
Scheme 48: Synthesis of thietanes 248a,b from diaryl thione 184b and ketene acetals 247a,b.
Scheme 49: Photocycloadditions of acridine-9-thiones 249 and pyridine-4(1H)-thione (250) with 2-methylacrynitr...
Scheme 50: Synthesis of thietanes via the photo [2 + 2] cycloaddition of mono-, di-, and trithiobarbiturates 2...
Scheme 51: Synthesis of spirothietanes via the photo [2 + 2] cycloaddition of 1,1,3-trimethyl-2-thioxo-1,2-dih...
Scheme 52: Synthesis of spirothietanes via the photo [2 + 2] cycloaddition of thiocoumarin 286 with olefins.
Scheme 53: Photochemical synthesis of thietanes 296–299 from semicyclic and acyclic thioimides 292–295 and 2,3...
Scheme 54: Photochemical synthesis of spirothietane 301 from 1,3,3-trimethylindoline-2-thione (300) and isobut...
Scheme 55: Synthesis of spirobenzoxazolethietanes 303 via the photo [2 + 2] cycloaddition of alkyl and aryl 2-...
Scheme 56: Synthesis of spirothietanes from tetrahydrothioxoisoquinolines 306 and 307 with olefins.
Scheme 57: Synthesis of spirothietanes from 1,3-dihydroisobenzofuran-1-thiones 311 and benzothiophene-1-thione...
Scheme 58: Synthesis of 2-triphenylsilylthietanes from phenyl triphenylsilyl thioketone (316) with electron-po...
Scheme 59: Diastereoselective synthesis of spiropyrrolidinonethietanes 320 via the photo [2 + 2] cycloaddition...
Scheme 60: Synthesis of bicyclic thietane 323 via the photo [2 + 2] cycloaddition of 2,4-dioxo-3,4-dihydropyri...
Scheme 61: Photo-induced synthesis of fused thietane-2-thiones 325 and 326 from silacyclopentadiene 324 and ca...
Scheme 62: Synthesis of highly strained tricyclic thietanes 328 via the intramolecular photo [2 + 2] cycloaddi...
Scheme 63: Synthesis of tri- and pentacyclic thietanes 330 and 332, respectively, through the intramolecular p...
Scheme 64: Synthesis of tricyclic thietanes 334 via the intramolecular photo [2 + 2] cycloaddition of N-vinylt...
Scheme 65: Synthesis of tricyclic thietanes 336 via the intramolecular photo [2 + 2] cycloaddition of N-but-3-...
Scheme 66: Synthesis of tricyclic thietanes via the intramolecular photo [2 + 2] cycloaddition of N-but-3-enyl...
Scheme 67: Synthesis of tetracyclic thietane 344 through the intramolecular photo [2 + 2] cycloaddition of N-[...
Scheme 68: Synthesis of tri- and tetracyclic thietanes 348, 350, and 351, through the intramolecular photo [2 ...
Scheme 69: Synthesis of tetracyclic fused thietane 354 via the photo [2 + 2] cycloaddition of vinyl 2-thioxo-3H...
Scheme 70: Synthesis of highly rigid thietane-fused β-lactams via the intramolecular photo [2 + 2] cycloadditi...
Scheme 71: Asymmetric synthesis of a highly rigid thietane-fused β-lactam 356a via the intramolecular photo [2...
Scheme 72: Diastereoselective synthesis of the thietane-fused β-lactams via the intramolecular photo [2 + 2] c...
Scheme 73: Asymmetric synthesis of thietane-fused β-lactams 356 via the intramolecular photo [2 + 2] cycloaddi...
Scheme 74: Synthesis of the bridged bis(trifluoromethyl)thietane from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-di...
Scheme 75: Synthesis of the bridged-difluorothietane 368 from 2,2,4,4-tetrafluoro-1,3-dithietane (367) and qua...
Scheme 76: Synthesis of bis(trifluoromethyl)thietanes from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (3...
Scheme 77: Synthesis of 2,2-dimethylthio-4,4-di(trifluoromethyl)thietane (378) from 2,2,4,4-tetrakis(trifluoro...
Scheme 78: Formation of bis(trifluoromethyl)thioacetone (381) through nucleophilic attack of dithietane 363 by...
Scheme 79: Synthesis of 2,2-bis(trifluoromethyl)thietanes from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietan...
Scheme 80: Synthesis of the bridged bis(trifluoromethyl)thietane 364 from of 2,2,4,4-tetrakis(trifluoromethyl)...
Scheme 81: Synthesis of 2,4-diiminothietanes 390 from alkenimines and 4-methylbenzenesulfonyl isothiocyanate (...
Scheme 82: Synthesis of arylidene 2,4-diiminothietanes 393 starting from phosphonium ylides 391 and isothiocya...
Scheme 83: Synthesis of thietane-2-ylideneacetates 397 through a DABCO-catalyzed formal [2 + 2] cycloaddition ...
Scheme 84: Synthesis of 3-substituted thietanes 400 from (1-chloroalkyl)thiiranes 398.
Scheme 85: Synthesis of N-(thietane-3-yl)azaheterocycles 403 and 404 through reaction of chloromethylthiirane (...
Scheme 86: Synthesis of 3-sulfonamidothietanes 406 from sulfonamides and chloromethylthiirane (398a).
Scheme 87: Synthesis of N-(thietane-3-yl)isatins 408 from chloromethylthiirane (398a) and isatins 407.
Scheme 88: Synthesis of 3-(nitrophenyloxy)thietanes 410 from nitrophenols 409 and chloromethylthiirane (398a).
Scheme 89: Synthesis of N-aryl-N-(thietane-3-yl)cyanamides 412 from N-arylcyanamides 411 and chloromethylthiir...
Scheme 90: Synthesis of 1-(thietane-3-yl)pyrimidin-2,4(1H,3H)-diones 414 from chloromethylthiirane (398a) and ...
Scheme 91: Synthesis of 2,4-diiminothietanes 418 from 2-iminothiiranes 416 and isocyanoalkanes 415.
Scheme 92: Synthesis of 2-vinylthietanes 421 from thiiranes 419 and 3-chloroallyl lithium (420).
Scheme 93: Synthesis of thietanes from thiiranes 419 and trimethyloxosulfonium iodide 424.
Scheme 94: Mechanism for synthesis of thietanes 425 from thiiranes 419 and trimethyloxosulfonium iodide 424.
Scheme 95: Synthesis of functionalized thietanes from thiiranes and dimethylsulfonium acylmethylides.
Scheme 96: Mechanism for the rhodium-catalyzed synthesis of functionalized thietanes 429 from thiiranes 419 an...
Scheme 97: Synthesis of 3-iminothietanes 440 through thermal isomerization from 4,5-dihydro-1,3-oxazole-4-spir...
Scheme 98: Synthesis of thietanes 443 from 3-chloro-2-methylthiolane (441) through ring contraction.
Scheme 99: Synthesis of an optically active thietanose 447 from D-xylose involving a ring contraction.
Scheme 100: Synthesis of optically thietane 447 via the DAST-mediated ring contraction of 448.
Scheme 101: Synthesis of the optically thietane nucleoside 451 via the ring contraction of thiopentose in 450.
Scheme 102: Synthesis of spirothietane 456 from 3,3,5,5-tetramethylthiolane-2,4-dithione (452) and benzyne (453...
Scheme 103: Synthesis of thietanes 461 via photoisomerization of 2H,6H-thiin-3-ones 459.
Scheme 104: Phosphorodithioate-mediated synthesis of 1,4-diarylthietanes 465.
Scheme 105: Mechanism of the phosphorodithioate-mediated synthesis of 1,4-diarylthietanes 465.
Scheme 106: Phosphorodithioate-mediated synthesis of trisubstituted thietanes (±)-470.
Scheme 107: Mechanism on the phosphorodithioate-mediated synthesis of trisubstituted thietanes.
Scheme 108: Phosphorodithioate-mediated synthesis of thietanes (±)-475.
Scheme 109: Phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes from aldehydes 476 and acrylon...
Scheme 110: Phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes via a one-pot three-component ...
Scheme 111: Mechanism for the phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes via three-co...
Scheme 112: Phosphorodithioate-mediated synthesis of substituted 3-nitrothietanes.
Scheme 113: Mechanism on the phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes (±)-486.
Scheme 114: Asymmetric synthesis of (S)-2-phenylthietane (497).
Scheme 115: Asymmetric synthesis of optically active 2,4-diarylthietanes.
Scheme 116: Synthesis of 3-acetamidothietan-2-one 503 via the intramolecular thioesterification of 3-mercaptoal...
Scheme 117: Synthesis of 4-substituted thietan-2-one via the intramolecular thioesterification of 3-mercaptoalk...
Scheme 118: Synthesis of 4,4-disubstituted thietan-2-one 511 via the intramolecular thioesterification of the 3...
Scheme 119: Synthesis of a spirothietan-2-one 514 via the intramolecular thioesterification of 3-mercaptoalkano...
Scheme 120: Synthesis of thiatetrahydrolipstatin starting from (S)-(−)-epichlorohydrin ((S)-142a).
Scheme 121: Synthesis of 2-phenethyl-4-(propan-2-ylidene)thietane (520) from 5-bromo-6-methyl-1-phenylhept-5-en...
Scheme 122: Synthesis of 2-phenethyl-4-(propan-2-ylidene)thietane (520) directly from S-(5-bromo-6-methyl-1-phe...
Scheme 123: Synthesis of 2-alkylidenethietanes from S-(2-bromoalk-1-en-4-yl)thioacetates.
Scheme 124: Synthesis of 2-alkylidenethietanes from S-(2-bromo/chloroalk-1-en-4-yl)thiols.
Scheme 125: Synthesis of spirothietan-3-ol 548 from enone 545 and ammonium hydrosulfide.
Scheme 126: Asymmetric synthesis of the optically active thietanoside from cis-but-2-ene-1,4-diol (47).
Scheme 127: Synthesis of 2-alkylidenethietan-3-ols 557 via the fluoride-mediated cyclization of thioacylsilanes ...
Scheme 128: Synthesis of 2-iminothietanes via the reaction of propargylbenzene (558) and isothiocyanates 560 in...
Scheme 129: Synthesis of 2-benzylidenethietane 567 via the nickel complex-catalyzed electroreductive cyclizatio...
Scheme 130: Synthesis of 2-iminothietanes 569 via the photo-assisted electrocyclic reaction of N-monosubstitute...
Scheme 131: Synthesis of ethyl 3,4-diiminothietane-2-carboxylates from ethyl thioglycolate (570) and bis(imidoy...
Scheme 132: Synthesis of N-(thietan-3-yl)-α-oxoazaheterocycles from azaheterocyclethiones and chloromethyloxira...
Scheme 133: Synthesis of thietan-3-yl benzoate (590) via the nickel-catalyzed intramolecular reductive thiolati...
Scheme 134: Synthesis of 2,2-bis(trifluoromethyl)thietane from 3,3-bis(trifluoromethyl)-1,2-dithiolane.
Scheme 135: Synthesis of thietanes from enamines and sulfonyl chlorides.
Scheme 136: Synthesis of spirothietane 603 via the [2 + 3] cycloaddition of 2,2,4,4-tetramethylcyclobutane-1,3-...
Scheme 137: Synthesis of thietane (605) from 1-bromo-3-chloropropane and sulfur.
Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations
- Rafia Siddiqui and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26
- neutrality; (iii) the use of household bulbs or LEDs as light sources under operationally simple reaction conditions; (iv) the high redox potential of photocatalysts that can manipulate the oxidation states of transition metal catalysts [54][55]. They have also found applications in novel solar cell
- ], for light harvesting, etc. [79]. On the other hand, in metallaphotocatalysis (dual catalytic systems), it has been observed that the efficiency of transition metal catalysts can be enhanced with photoredox catalysts, viz, functioning under mild reaction conditions, opening of new activation modes, and
Graphical Abstract
Figure 1: List of photoredox catalysts used for C–H bond functionalizations.
Figure 2: List of metal-based photoredox catalysts used in this review article.
Figure 3: Jablonski diagram.
Figure 4: Photoredox catalysis via reductive or oxidative pathways. D = donor, A = acceptor, S = substrate, P...
Figure 5: Schematic representation of the combination of photoredox catalysis and transition metal catalysis.
Scheme 1: Weinreb amide C–H olefination.
Figure 6: Mechanism for the formation of 21 from 19 using photoredox catalyst 11.
Scheme 2: C–H olefination of phenolic ethers.
Scheme 3: Decarboxylative acylation of acetanilides.
Figure 7: Mechanism for the formation of 30 from acetanilide derivatives.
Scheme 4: Synthesis of fluorenone derivatives by intramolecular deoxygenative acylation of biaryl carboxylic ...
Figure 8: Mechanism for the photoredox-catalyzed synthesis of fluorenone derivatives.
Scheme 5: Synthesis of benzothiazoles via aerobic C–H thiolation.
Figure 9: Plausible mechanism for the construction of benzothiazoles from benzothioamides.
Scheme 6: Synthesis of benzothiazoles via oxidant-free C–H thiolation.
Figure 10: Mechanism involved in the synthesis of benzothiazoles via oxidant-free C–H thiolation.
Scheme 7: Synthesis of indoles via C–H cyclization of anilides with alkynes.
Scheme 8: Preparation of 3-trifluoromethylcoumarins via C–H cyclization of arylpropiolate esters.
Figure 11: Mechanistic pathway for the synthesis of coumarin derivatives via C–H cyclization.
Scheme 9: Monobenzoyloxylation without chelation assistance.
Figure 12: Plausible mechanism for the formation of 71 from 70.
Scheme 10: Aryl-substituted arenes prepared by inorganic photoredox catalysis using 12a.
Figure 13: Proposed mechanism for C–H arylations in the presence of 12a and a Pd catalyst.
Scheme 11: Arylation of purines via dual photoredox catalysis.
Scheme 12: Arylation of substituted arenes with an organic photoredox catalyst.
Scheme 13: C–H trifluoromethylation.
Figure 14: Proposed mechanism for the trifluoromethylation of 88.
Scheme 14: Synthesis of benzo-3,4-coumarin derivatives.
Figure 15: Plausible mechanism for the synthesis of substituted coumarins.
Scheme 15: Oxidant-free oxidative phosphonylation.
Figure 16: Mechanism proposed for the phosphonylation reaction of 100.
Scheme 16: Nitration of anilines.
Figure 17: Plausible mechanism for the nitration of aniline derivatives via photoredox catalysis.
Scheme 17: Synthesis of carbazoles via intramolecular amination.
Figure 18: Proposed mechanism for the formation of carbazoles from biaryl derivatives.
Scheme 18: Synthesis of substituted phenols using QuCN.
Figure 19: Mechanism for the synthesis of phenol derivatives with photoredox catalyst 8.
Scheme 19: Synthesis of substituted phenols with DDQ (5).
Figure 20: Possible mechanism for the generation of phenols with the aid of photoredox catalyst 5.
Scheme 20: Aerobic bromination of arenes using an acridinium-based photocatalyst.
Scheme 21: Aerobic bromination of arenes with anthraquinone.
Figure 21: Proposed mechanism for the synthesis of monobrominated compounds.
Scheme 22: Chlorination of benzene derivatives with Mes-Acr-MeClO4 (2).
Figure 22: Mechanism for the synthesis of 131 from 132.
Scheme 23: Chlorination of arenes with 4CzIPN (5a).
Figure 23: Plausible mechanism for the oxidative photocatalytic monochlorination using 5a.
Scheme 24: Monofluorination using QuCN-ClO4 (8).
Scheme 25: Fluorination with fluorine-18.
Scheme 26: Aerobic amination with acridinium catalyst 3a.
Figure 24: Plausible mechanism for the aerobic amination using acridinium catalyst 3a.
Scheme 27: Aerobic aminations with semiconductor photoredox catalyst 18.
Scheme 28: Perfluoroalkylation of arenes.
Scheme 29: Synthesis of benzonitriles in the presence of 3a.
Figure 25: Plausible mechanism for the synthesis of substituted benzonitrile derivatives in the presence of 3a....
Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A
- Qiao Li,
- Chen Zhuang,
- Donghua Wang,
- Wei Zhang,
- Rongxuan Jia,
- Fengxia Sun,
- Yilin Zhang and
- Yunfei Du
Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291
- high reaction temperature, extended reaction time, involvement of transition metal catalysts, and low yield. In these regards, the development of alternative approaches that can realize an efficient synthesis of chromones under mild conditions is desirable. In recent decades, hypervalent iodine
Graphical Abstract
Figure 1: Biologically active chromone derivatives.
Scheme 1: Methods for the synthesis of chromones via dehydrogenative oxidation of chromanones.
Scheme 2: Substrate scope studies. Reaction conditions: 1 (1.0 mmol), PhIO (2.0 mmol), DMF (6 mL), rt. Isolat...
Scheme 3: Control experiments for mechanistic studies.
Scheme 4: Proposed reaction mechanism.
Scheme 5: Application of the reported method to the synthesis of frutinone A.
A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage
- Kesari Lakshmi Manasa,
- Yellaiah Tangella,
- Namballa Hari Krishna and
- Mallika Alvala
Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182
- new C–N bonds in the presence of transition metal catalysts [25][26][27][28][29][30][31][32][33][34]. Tang and Jiao reported copper catalyzed C–C single bond cleavage and C–N bond formation [35]. However, the transition metal catalysts and additives employed in these transformations are toxic and
Graphical Abstract
Scheme 1: Comparison of our work with previous studies.
Scheme 2: Scope of pyridinium salts and benzylamine substrates. Reaction conditions: 1 (1 mmol), 2 (1 mmol), ...
Scheme 3: Scope of pyridinium salts and benzyl alcohol substrates. Reaction conditions: 1 (1 mmol), 4 (1 mmol...
Scheme 4: Scope of pyridinium salts, primary and secondary amine substrates. Reaction conditions: 1 (1 mmol), ...
Scheme 5: Control experiments for the oxidative cleavage of C–C bonds.
Scheme 6: Plausible reaction mechanism for the synthesis of N-alkylated benzamides 3.
Aqueous olefin metathesis: recent developments and applications
- Valerio Sabatino and
- Thomas R. Ward
Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39
- -selective protein modification through aqueous CM [83], thus expanding the catalytic repertoire of protein modification with transition-metal catalysts [84][85][86][87]. A variant of subtilisin from Bacillus lentus containing a single cysteine (SBL-S156C) was modified by direct allylation to install an
Graphical Abstract
Scheme 1: Most common metathesis reactions. Ring-opening metathesis polymerization (ROMP), acyclic diene meta...
Scheme 2: Catalytic cycle for metathesis proposed by Chauvin.
Figure 1: Some of the most representative catalysts for aqueous metathesis. a) Well-defined ruthenium catalys...
Scheme 3: First aqueous ROMP reactions catalyzed by ruthenium(III) salts.
Scheme 4: Degradation pathway of first generation Grubbs catalyst (G-I) in methanol.
Scheme 5: Synthesis of Blechert-type catalysts 19 and 20.
Figure 2: Chemical structure and components of amphiphilic molecule PTS and derivatives.
Scheme 6: RCM of selected substrates in the presence of the surfactant PTS. Conditionsa: The reaction was car...
Scheme 7: RCM reactions of substrates 31 and 33 with the encapsulated G-II catalyst.
Scheme 8: Living ROMP of norbornene derivatives 35 and 36 with phosphine-based catalysts bearing quaternary a...
Scheme 9: Synthesis of water-soluble catalysts 3 and 4 bearing quaternary ammonium tags.
Scheme 10: In situ formation of catalyst 5 bearing a quaternary ammonium group.
Scheme 11: Catalyst recycling of an ammonium-bearing catalyst.
Scheme 12: Removal of the water-soluble catalyst 12 through host–guest interaction with silica-gel-supported β...
Scheme 13: Selection of artificial metathases reported by Ward and co-workers (ArM 1 based on biotin–(strept)a...
Figure 3: In vivo metathesis with an artificial metalloenzyme based on the biotin–streptavidin technology.
Scheme 14: Artificial metathase based on covalent anchoring approach. α-Chymotrypsin interacts with catalyst 66...
Scheme 15: Assembling an artificial metathase (ArM 4) based on the small heat shock protein from M. Jannaschii...
Scheme 16: Artificial metathases based on cavity-size engineered β-barrel protein nitrobindin (NB4exp). The HG...
Scheme 17: Artificial metathase based on cutinase (ArM 8) and resulting metathesis activities.
Scheme 18: Site-specific modification of proteins via aqueous cross-metathesis. The protein structure is based...
Scheme 19: a) Allyl homocysteine (Ahc)-modified proteins as CM substrates. b) Incorporation of Ahc in the Fc p...
Scheme 20: On-DNA cross-metathesis reaction of allyl sulfide 99.
Scheme 21: Preparation of BODIPY-containing profluorescent probes 102 and 104.
Scheme 22: Metathesis-based ethylene detection in live cells.
Scheme 23: First example of stapled peptides via olefin metathesis.
Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes
- Guillaume Ernouf,
- Jean-Louis Brayer,
- Christophe Meyer and
- Janine Cossy
Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29
- -Δ1-pyrazoline [39]) or by pyrolysis of the sodium salt of 3-propionyloxytetramethylcyclobutanone tosyl hydrazone [40]. It is also worth mentioning that completely divergent reactivities have also been reported for cyclopropenylcarbinyl esters in the presence of transition metal catalysts [41][42
Graphical Abstract
Scheme 1: Representative strategies for the formation of alkylidenecyclopropanes from cyclopropenes and scope...
Scheme 2: [2,3]-Sigmatropic rearrangement of phosphinites 2a–h.
Scheme 3: [2,3]-Sigmatropic rearrangement of a phosphinite derived from enantioenriched cyclopropenylcarbinol...
Scheme 4: Selective reduction of phosphine oxide (E)-3f.
Scheme 5: Attempted thermal [2,3]-sigmatropic rearrangement of phosphinite 6a.
Scheme 6: Computed activation barriers and free enthalpies.
Scheme 7: [2,3]-Sigmatropic rearrangement of phosphinites 6a–j.
Scheme 8: Proposed mechanism for the Lewis base-catalyzed rearrangement of phosphinites 6.
Scheme 9: [3,3]-Sigmatropic rearrangement of tertiary cyclopropenylcarbinyl acetates 10a–c.
Scheme 10: [3,3]-Sigmatropic rearrangement of secondary cyclopropenylcarbinyl esters 10d–h.
Scheme 11: [3,3]-Sigmatropic rearrangement of trichoroacetimidates 12a–i.
Scheme 12: Reaction of trichloroacetamide 13f with pyrrolidine.
Scheme 13: Catalytic hydrogenation of (arylmethylene)cyclopropropane 13f.
Scheme 14: Instability of trichloroacetimidates 21a–c derived from cyclopropenylcarbinols 20a–c.
Scheme 15: [3,3]-Sigmatropic rearrangement of cyanate 27 generated from cyclopropenylcarbinyl carbamate 26.
Scheme 16: Synthesis of alkylidene(aminocyclopropane) derivatives 30–37 from carbamate 26.
Scheme 17: Scope of the dehydration–[3,3]-sigmatropic rearrangement sequence of cyclopropenylcarbinyl carbamat...
Scheme 18: Formation of trifluoroacetamide 50 from carbamate 49.
Scheme 19: Formation of alkylidene[(N-trifluoroacetylamino)cyclopropanes] 51–54.
Scheme 20: Diastereoselective hydrogenation of alkylidenecyclopropane 51.
Scheme 21: Ireland–Claisen rearrangement of cyclopropenylcarbinyl glycolates 56a–l.
Scheme 22: Synthesis and Ireland–Claisen rearrangement of glycolate 61 possessing gem-diester substitution at ...
Scheme 23: Synthesis of alkylidene(gem-difluorocyclopropanes) 66a–h, and 66k–n from propargyl glycolates 64a–n....
Scheme 24: Ireland–Claisen rearrangement of N,N-diBoc glycinates 67a and 67b.
Scheme 25: Diastereoselective hydrogenation of alkylidenecyclopropanes 58a and 74.
Scheme 26: Synthesis of functionalized gem-difluorocyclopropanes 76 and 77 from alkylidenecyclopropane 66a.
Scheme 27: Access to oxa- and azabicyclic compounds 78–80.
Oxidative radical ring-opening/cyclization of cyclopropane derivatives
- Yu Liu,
- Qiao-Lin Wang,
- Zan Chen,
- Cong-Shan Zhou,
- Bi-Quan Xiong,
- Pan-Liang Zhang,
- Chang-An Yang and
- Quan Zhou
Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23
- transformation just needed 2 equiv of TBHP (42), avoiding using transition metal catalysts, ligands, and bases. In the proposed mechanism (Scheme 11), the tert-butoxyl radical 43, which was formed from THBP (42) under heating conditions, attackes the ether 40 to afford the radical 44 [69][70][71][72]. Next, the
Graphical Abstract
Scheme 1: The oxidative radical ring-opening/cyclization of cyclopropane derivatives.
Scheme 2: Mn(OAc)3-mediated oxidative radical ring-opening and cyclization of MCPs with malonates.
Scheme 3: Mn(III)-mediated oxidative radical ring-opening and cyclization of MCPs with 1,3-dicarbonyl compoun...
Scheme 4: Heat-promoted ring-opening/cyclization of MCPs with elemental chalgogens.
Scheme 5: Copper(II) acetate-mediated oxidative radical ring-opening and cyclization of MCPs with diphenyl di...
Scheme 6: AIBN-promoted oxidative radical ring-opening and cyclization of MCPs with benzenethiol.
Scheme 7: AIBN-mediated oxidative radical ring-opening and cyclization of MCPs with diethyl phosphites.
Scheme 8: Organic-selenium induced radical ring-opening and cyclization of MCPs derivatives (cyclopropylaldeh...
Scheme 9: Copper(I)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs with To...
Scheme 10: Ag(I)-mediated trifluoromethylthiolation/ring-opening/cyclization of MCPs with AgSCF3.
Scheme 11: oxidative radical ring-opening and cyclization of MCPs with α-C(sp3)-–H of ethers.
Scheme 12: Oxidative radical ring-opening and cyclization of MCPs with aldehydes.
Scheme 13: Cu(I) or Fe(II)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs d...
Scheme 14: Rh(II)-catalyzed oxidative radical ring-opening and cyclization of MCPs.
Scheme 15: Ag(I)-catalyzed oxidative radical amination/ring-opening/cyclization of MCPs derivatives.
Scheme 16: Heating-promoted radical ring-opening and cyclization of MCP derivatives (arylvinylidenecyclopropan...
Scheme 17: Bromine radical-mediated ring-opening of alkylidenecyclopropanes.
Scheme 18: Fluoroalkyl (Rf) radical-mediated ring-opening of MCPs.
Scheme 19: Visible-light-induced alkylation/ring-opening/cyclization of cyclopropyl olefins with bromides.
Scheme 20: Mn(III)-mediated ring-opening and [3 + 3]-annulation of cyclopropanols and vinyl azides.
Scheme 21: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with quinones.
Scheme 22: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with heteroarenes.
Scheme 23: Cu(I)-catalyzed oxidative ring-opening/trifluoromethylation of cyclopropanols.
Scheme 24: Cu(I)-catalyzed oxidative ring-opening and trifluoromethylation/trifluoromethylthiolation of cyclop...
Scheme 25: Ag(I)-mediated oxidative ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 26: Photocatalyzed ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 27: Na2S2O8-promoted ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 28: Ag(I)-catalyzed ring-opening and chlorination of cyclopropanols with aldehydes.
Scheme 29: Ag(I)-catalyzed ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 30: Na2S2O8-promoted ring-opening/alkylation of cyclopropanols with acrylamides.
Scheme 31: Cyclopropanol ring-opening initiated tandem cyclization with acrylamides or 2-isocyanobiphenyls.
Scheme 32: Ag(II)-mediated oxidative ring-opening/fluorination of cyclopropanols with AgF2.
Scheme 33: Cu(II)-catalyzed ring-opening/fluoromethylation of cyclopropanols with sulfinate salts.
Scheme 34: Cu(II)-catalyzed ring-opening/sulfonylation of cyclopropanols with sulfinate salts.
Scheme 35: Na2S2O8-promoted ring-opening/arylation of cyclopropanols with propiolamides.
Scheme 36: The ring-opening and [3 + 2]-annulation of cyclopropanols with α,β-unsaturated aldehydes.
Scheme 37: Cu(II)-catalyzed ring-opening/arylation of cyclopropanols with aromatic nitrogen heterocyles.
Scheme 38: Ag(I)-catalyzed ring-opening and difluoromethylthiolation of cyclopropanols with PhSO2SCF2H.
Scheme 39: Ag(I)-catalyzed ring-opening and acylation of cyclopropanols with aldehydes.
Scheme 40: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of 2-oxyranyl ketones.
Scheme 41: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of linear enones.
Scheme 42: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of metabolite.
Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region
- Aude-Héloise Bonardi,
- Frédéric Dumur,
- Guillaume Noirbent,
- Jacques Lalevée and
- Didier Gigmes
Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282
- transition metal catalysts classically used as initiators were established and 4CzIPN could provide performances comparable to that obtained with metal complexes. As specificity, 4CzIPN is characterized by a broad absorption extending from 250 nm to ≈500 nm. Its different photophysical characteristics are
Graphical Abstract
Figure 1: Typical oxidative and reductive cycle for a photoredox catalyst (PC).
Figure 2: Transitions involved in absorbing species containing π, σ and n electrons.
Figure 3: Ligand to metal charge transfer (illustrated here for a d6 metal complex).
Figure 4: Metal to ligand charge transfer (illustrated here for a d5 metal complex).
Scheme 1: Structures of additives involved in the photoredox catalytic cycles.
Figure 5: Catalytic cycles involved with iodonium salt and (A) (TMS)3SiH, (B) NVK and (C) EDB.
Scheme 2: Structures of photoredox metal-based catalysts.
Scheme 3: Photocatalytical cycle for the Ru complex.
Scheme 4: Structures of photoredox organocatalysts.
Scheme 5: Diversity of the chemical structures of photoredox organocatalysts.
Scheme 6: Structures of benchmarked monomers.
Scheme 7: Structure of the CARET additive.
Scheme 8: Photoredox catalysis mechanism of a visible light-mediated living radical polymerization. (Abbrevia...
Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis
- Daniel F. Sauer,
- Johannes Schiffels,
- Takashi Hayashi,
- Ulrich Schwaneberg and
- Jun Okuda
Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265
- metathesis constitutes the rearrangement of C=C double bonds in the presence of transition metal catalysts based on V, Mo, W, Re, Ru, and Os together with alkylating co-catalysts. This transformation is widely used in organic synthesis as well as in polymerization of various unsaturated monomers [1
Graphical Abstract
Scheme 1: Left: Mechanism of the olefin metathesis reaction postulated by Chauvin [2]. Right: Potential influenc...
Scheme 2: (i) Ring-opening metathesis polymerization (ROMP), (ii) ring-closing metathesis (RCM) and (iii) cro...
Figure 1: Common anchoring strategies for metal-complex or metal ion incorporation into protein scaffolds.
Scheme 3: Biotinylated GH-type catalysts for conjugation to (strept)avidin and their catalyzed ring-closing m...
Scheme 4: Whole-cell artificial metatheases designed by Ward et al. [47].
Scheme 5: Coupling of GH-type catalysts Ru-4/5/6 to NB4 or NB11.
Scheme 6: Anchoring and refolding of GH-type catalysts Ru-4/5/6 to FhuA.
Figure 2: Top: NB4 (PDB 3WJB); bottom: NB4exp. Highlighted in blue are the additional two β-sheets. Highlight...
Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps
- Sambasivarao Kotha,
- Milind Meshram and
- Chandravathi Chakkapalli
Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223
- ; metathesis; polycycles; Suzuki–Miyaura cross coupling; Introduction Transition-metal catalysts are used in metathesis and cross-coupling reactions. Such advances have opened the door for efficient construction of C–C bonds in organic synthesis. These catalysts tolerate diverse functional groups and the
Graphical Abstract
Figure 1: Various catalysts used for metathesis reactions.
Scheme 1: SM coupling and RCM protocol to substituted indene derivative 10.
Scheme 2: Synthesis of polycycles via SM and RCM approach.
Figure 2: Various angucyclines.
Scheme 3: SM coupling and RCM protocol to the benz[a]anthracene skeleton 26.
Scheme 4: Synthesis of substituted spirocycles via RCM and SM sequence.
Scheme 5: Synthesis of highly functionalized bis-spirocyclic derivative 37.
Scheme 6: Synthesis of spirofluorene derivatives via RCM and SM coupling sequence.
Scheme 7: Synthesis of truxene derivatives via RCM and SM coupling.
Scheme 8: Synthesis of substituted isoquinoline derivative via SM and RCM protocol.
Scheme 9: Synthesis to 8-aryl substituted coumarin 64 via RCM and SM sequence.
Scheme 10: Synthesis of cyclic sulfoximine 70 via SM and RCM as key steps.
Scheme 11: Synthesis of 1-benzazepine derivative 75 via SM and RCM as key steps.
Scheme 12: Synthesis of naphthoxepine derivative 79 via RCM followed by SM coupling.
Scheme 13: Sequential CM and SM coupling approach to Z-stilbene derivative 85.
Scheme 14: Synthesis of substituted trans-stilbene derivatives via SM coupling and RCM.
Scheme 15: Synthesis of biaryl derivatives via sequential EM, DA followed by SM coupling.
Scheme 16: Synthesis of the dibenzocyclooctadiene core of schisandrene.
Scheme 17: Synthesis of cyclophane 115 via SM coupling and RCM as key steps.
Scheme 18: Synthesis of cyclophane 120 and 122 via SM coupling and RCM as key steps.
Scheme 19: Synthesis of cyclophanes via SM and RCM.
Scheme 20: Synthesis of MK-6325 (141) via RCM and SM coupling.
Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source
- Tetsuaki Fujihara and
- Yasushi Tsuji
Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221
- kinetic stability of CO2 sometimes limits its utility. Classically, harsh reaction conditions such as high temperature and high pressure of CO2 were required. To overcome these problems, the use of transition-metal catalysts has been considered as a fundamental and reliable method. In the last decade
Graphical Abstract
Scheme 1: Optimization of the Co-catalyzed carboxylation of 1a.
Scheme 2: Co-catalyzed carboxylation of propargyl acetates 1.
Scheme 3: Plausible reaction mechanism for the Co-catalyzed carboxylation of propargyl acetates 1.
Scheme 4: Optimization of the Co-catalyzed carboxylation of 3a.
Scheme 5: Co-catalyzed carboxylation of vinyl triflates 3.
Scheme 6: Co-catalyzed carboxylation of a sterically hindered aryl triflate 5.
Scheme 7: Optimization of the Co-catalyzed carboxylation of 7a.
Scheme 8: Scope of the reductive carboxylation of α,β-unsaturated nitriles 7.
Scheme 9: Scope of the carboxylation of α,β-unsaturated carboxamides 9.
Scheme 10: Optimization of the Co-catalyzed carboxylation of 11a.
Scheme 11: Scope of the carboxylation of allylarenes 11.
Scheme 12: Scope of the carboxylation of 1,4-diene derivatives 14.
Scheme 13: Plausible reaction mechanism for the Co-catalyzed C(sp3)–H carboxylation of allylarenes.
Scheme 14: Optimization of the Co-catalyzed carboxyzincation of 16a.
Scheme 15: Derivatization of the carboxyzincated product.
Scheme 16: Co-catalyzed carboxyzincation of alkynes 16.
Scheme 17: Plausible reaction mechanism for the Co-catalyzed carboxyzincation of alkynes 16.
Scheme 18: Co-catalyzed four-component coupling of alkynes 16, acrylates 18, CO2, and zinc.
Scheme 19: Proposed reaction mechanism for the Co-catalyzed four-component coupling.
Scheme 20: Visible-light-driven hydrocarboxylation of alkynes.
Scheme 21: Visible-light-driven synthesis of γ-hydroxybutenolides from ortho-ester-substituted aryl alkynes.
Scheme 22: One-pot synthesis of coumarines and 2-quinolones via hydrocarboxylation/alkyne isomerization/cycliz...
Scheme 23: Proposed reaction mechanism for the Co-catalyzed carboxylative cyclization of ortho-substituted aro...
Scheme 24: Rh-catalyzed carboxylation of arylboronic esters 25.
Scheme 25: Rh-catalyzed carboxylation of alkenylboronic esters 27.
Scheme 26: Plausible reaction mechanism for the Rh-catalyzed carboxylation of arylboronic esters 25.
Scheme 27: Ligand effect on the Rh-catalyzed carboxylation of 2-phenylpyridine 29a.
Scheme 28: Rh-catalyzed chelation-assisted C(sp2)–H bond carboxylation with CO2.
Scheme 29: Reaction mechanism for the Rh-catalyzed C(sp2)–H carboxylation of 2-pyridylarenes 29.
Scheme 30: Carboxylation of C(sp2)–H bond with CO2.
Scheme 31: Carboxylation of C(sp2)–H bond with CO2.
Scheme 32: Reaction mechanism for the Rh-catalyzed C(sp2)–H carboxylation of 2-arylphenols 34.
Scheme 33: Hydrocarboxylation of styrene derivatives with CO2.
Scheme 34: Hydrocarboxylation of α,β-unsaturated esters with CO2.
Scheme 35: Asymmetric hydrocarboxylation of α,β-unsaturated esters with CO2.
Scheme 36: Proposed reaction mechanism for the Rh-catalyzed hydrocarboxylation of C–C double bonds with CO2.
Scheme 37: Visible-light-driven hydrocarboxylation with CO2.
Scheme 38: Visible-light-driven Rh-catalyzed hydrocarboxylation of C–C double bonds with CO2.
Scheme 39: Optimization of reaction conditions on the Rh-catalyzed [2 + 2 + 2] cycloaddition of diyne 42a and ...
Scheme 40: [2 + 2 + 2] Cycloaddition of diyne and CO2.
Scheme 41: Proposed reaction pathways for the Rh-catalyzed [2 + 2 + 2] cycloaddition of diyne and CO2.
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
- methodologies have been developed to build new C–X (X = carbon or heteroatom) bonds [7][8][9][10] and they offer efficient routes to the synthesis of natural products, materials, agrochemicals, polymers, and pharmaceuticals [11][12][13][14][15]. Specifically, the first-row transition metal catalysts, which are
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.
An amine protecting group deprotectable under nearly neutral oxidative conditions
- Shahien Shahsavari,
- Chase McNamara,
- Mark Sylvester,
- Emily Bromley,
- Savannah Joslin,
- Bao-Yuan Lu and
- Shiyue Fang
Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149
- , we used the conditions we developed earlier for the deprotection of Dmoc protected ODNs directly without making additional efforts to evaluate other conditions [18]. These conditions could be superior to reported conditions [13][15][17][21] because they do not require transition metal catalysts or
Graphical Abstract
Scheme 1: Dmoc and dM-Dmoc protection and deprotection of amines.
Scheme 2: Selective deprotection of dM-Dmoc-, Boc- and Fmoc-protected amines.
Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting
- Jonas Weidner,
- Stefan Barwe,
- Kirill Sliozberg,
- Stefan Piontek,
- Justus Masa,
- Ulf-Peter Apfel and
- Wolfgang Schuhmann
Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121
- heterogeneous catalysts for the oxidation of HMF. However, the high cost of the noble metal catalysts has aroused interest in transition metal catalysts and alternative methods for the oxidation of HMF. The electrochemical oxidation of HMF to FDCA was first reported in 1991 by Grabowski and co-workers [25
Graphical Abstract
Scheme 1: Conventional water electrolyzer (a) and electrolyzer using an alternative anode reaction (b) in alk...
Figure 1: XRD patterns of Co2Si, CoTe, CoAs. Cobalt is indicated by (+) and signals corresponding to the desi...
Figure 2: Linear sweep voltammograms of CoP, CoB, CoTe, Co2Si, CoAs modified and blank Ni RDEs for the OER (a...
Figure 3: SEM micrographs of bare (a, b) and CoB-modified (c, d) NF with 1000× or 20000× magnification, respe...
Figure 4: a) Reaction pathways of HMF oxidation; b) chromatograms at various times during constant potential ...
Figure 5: Concentration vs time curve for HMF, HMFCA, DFF, FFCA and FDCA (a); bar diagram of the faradaic eff...
