Bifunctional catalysis concerns the use of low molecular weight, structurally defined molecules possessing two distinct functional groups to bring about new reactivity or selectivity in a reaction of interest. The reactions are typically polar addition reactions of pronucleophiles and electrophiles where, ideally, simple low-cost starting materials are converted into high-value, stereochemically defined products through the action of the bifunctional catalyst system. The present Thematic Series serves to highlight the current state-of-the-art of bifunctional catalysis from new bifunctional catalyst design and development, their application in new asymmetric metholodgy development, to their application in natural product and drug target synthesis.
See also the Thematic Series:
Strategies in asymmetric catalysis
Sustainable catalysis
Graphical Abstract
Scheme 1: Diastereodivergent cascade Michael/Michael reaction using catalysts with the same absolute chiralit...
Scheme 2: Diastereodivergent enantioselective Michael reaction using ethyl 2-nitropropanoate and β-nitrostyre...
Figure 1: ORTEP diagrams for anti-3a and syn-3o respectively.
Scheme 3: Proposed models to explain the stereochemical outcome of the reaction.
Graphical Abstract
Figure 1: Some chiral, bioactive isoindolinones.
Scheme 1: This work: 1) trans-1,2-cyclohexane diamine-based bifunctional ammonium salts 8 in the asymmetric s...
Scheme 2: Asymmetric cascade, crystallization and decarboxylation reaction.
Scheme 3: Proposed racemization pathways of isoindolinones 9 via retro-Michael process.
Scheme 4: Asymmetric synthesis of (S)-PD172938.
Scheme 5: Coupling of chiral acid 9 with p-tolylpiperazine and CuI arylation of chiral isoindolinones.
Graphical Abstract
Figure 1: Structure of PGI2 and beraprost (1).
Scheme 1: Retrosynthetic analysis of beraprost (1).
Scheme 2: Preparation of Michael precursors 7 and 8.
Scheme 3: First attempt at the synthesis of 2 from 6.
Scheme 4: Achievement of a formal synthesis of 2.
Graphical Abstract
Figure 1: a) Asymmetric α-hydroxylation of 2 in the presence of 1a. b) Asymmetric α-amination of 4 explored i...
Scheme 1: Substrate scope of α-amination.
Figure 2: NLE study of α-amination.
Scheme 2: α-Amination of 4a using 9 or 10 as catalyst.
Graphical Abstract
Scheme 1: An example of scalable synthesis.
Scheme 2: Hydrolysis reaction to produce a useful product.
Scheme 3: Proposed mechanism.
Graphical Abstract
Scheme 1: The strategy to construct chiral 3-substituted-3-hydroxy-1H-pyrrol-2(3H)-ones.
Figure 1: The X-ray structure of compound 4i.
Figure 2: A proposed transition state for the asymmetric Henry reaction.
Graphical Abstract
Figure 1: Bioactive 7-azaisatins and their derivatives.
Scheme 1: Further exploration with 7-azaisatin 1a and comparison with the previous work by Zhou [5].
Graphical Abstract
Scheme 1: The [3 + 2] annulation of α-substituted allenoates reported by He.
Scheme 2: Possible reaction mechanism.
Graphical Abstract
Figure 1: The structural diversity of the cinchona alkaloids, along with cupreine, cupreidine, β-isoquinidine...
Scheme 1: The original 6’-OH cinchona alkaloid organocatalytic MBH process, showing how the free 6’-OH is ess...
Scheme 2: Use of β-ICPD in an aza-MBH reaction.
Scheme 3: (a) The isatin motif is a common feature for MBH processes catalyzed by β-ICPD, as demonstrated by ...
Scheme 4: (a) Chen’s asymmetric MBH reaction. Good selectivity was dependent upon the presence of (R)-BINOL (...
Scheme 5: Lu and co-workers synthesis of a spiroxindole.
Scheme 6: Kesavan and co-workers’ synthesis of spiroxindoles.
Scheme 7: Frontier’s Nazarov cyclization catalyzed by β-ICPD.
Scheme 8: The first asymmetric nitroaldol process catalyzed by a 6’-OH cinchona alkaloid.
Scheme 9: A cupreidine derived catalyst induces a dynamic kinetic asymmetric transformation.
Scheme 10: Cupreine derivative 38 has been used in an organocatalytic asymmetric Friedel–Crafts reaction.
Scheme 11: Examples of 6’-OH cinchona alkaloid catalyzed processes include: (a) Deng’s addition of dimethyl ma...
Scheme 12: A diastereodivergent sulfa-Michael addition developed by Melchiorre and co-workers.
Scheme 13: Melchiorre’s vinylogous Michael addition.
Scheme 14: Simpkins’s TKP conjugate addition reactions.
Scheme 15: Hydrocupreine catalyst HCPN-59 can be used in an asymmetric cyclopropanation.
Scheme 16: The hydrocupreine and hydrocupreidine-based catalysts HCPN-65 and HCPD-67 demonstrate the potential...
Scheme 17: Jørgensen’s oxaziridination.
Scheme 18: Zhou’s α-amination using β-ICPD.
Scheme 19: Meng’s cupreidine catalyzed α-hydroxylation.
Scheme 20: Shi’s biomimetic transamination process for the synthesis of α-amino acids.
Scheme 21: β-Isocupreidine catalyzed [4 + 2] cycloadditions.
Scheme 22: β-Isocupreidine catalyzed [2+2] cycloaddition.
Scheme 23: A domino reaction catalyst by cupreidine catalyst CPD-30.
Scheme 24: (a) Dixon’s 6’-OH cinchona alkaloid catalyzed oxidative coupling. (b) An asymmetric oxidative coupl...
Graphical Abstract
Scheme 1: Activation of carbonyl compounds via enamine and iminium intermediates [2].
Scheme 2: Electronic and steric interactions present in enamine activation mode [2].
Scheme 3: Electrophilic activation of carbonyl compounds by a thiourea moiety.
Scheme 4: Asymmetric synthesis of dihydro-2H-pyran-6-carboxylate 3 using organocatalyst 4 [16].
Scheme 5: Possible hydrogen-bonding for the reaction of (E)-methyl 2-oxo-4-phenylbut-3-enoate [16].
Scheme 6: Asymmetric desymmetrization of 4,4-cyclohexadienones using the Michael addition reaction with malon...
Scheme 7: The enantioselective synthesis of α,α-disubstituted cycloalkanones using catalyst 11 [18].
Scheme 8: The enantioselective synthesis of indolo- and benzoquinolidine compounds through aza-Diels–Alder re...
Scheme 9: Enantioselective [5 + 2] cycloaddition [20].
Scheme 10: Asymmetric synthesis of oxazine derivatives 26 [21].
Scheme 11: Asymmetric synthesis of bicyclo[3.3.1]nonadienone, core 30 present in (−)-huperzine [22].
Scheme 12: Asymmetric inverse electron-demand Diels-Alder reaction catalyzed by amine-thiourea 34 [23].
Scheme 13: Asymmetric entry to morphan skeletons, catalyzed by amine-thiourea 37 [24].
Scheme 14: Asymmetric transformation of (E)-2-nitroallyl acetate [25].
Scheme 15: Proposed way of activation.
Scheme 16: Asymmetric synthesis of nitrobicyclo[3.2.1]octan-2-one derivatives [26].
Scheme 17: Asymmetric tandem Michael–Henry reaction catalyzed by 50 [27].
Scheme 18: Asymmetric Diels–Alder reactions of 3-vinylindoles 51 [29].
Scheme 19: Proposed transition state and activation mode of the asymmetric Diels–Alder reactions of 3-vinylind...
Scheme 20: Desymmetrization of meso-anhydrides by Chin, Song and co-workers [30].
Scheme 21: Desymmetrization of meso-anhydrides by Connon and co-workers [31].
Scheme 22: Asymmetric intramolecular Michael reaction [32].
Scheme 23: Asymmetric addition of malonate to 3-nitro-2H-chromenes 67 [33].
Scheme 24: Intramolecular desymmetrization through an intramolecular aza-Michael reaction [34].
Scheme 25: Enantioselective synthesis of (−)-mesembrine [34].
Scheme 26: A novel asymmetric Michael–Michael reaction [35].
Scheme 27: Asymmetric three-component reaction catalyzed by Takemoto’s catalyst 77 [46].
Scheme 28: Asymmetric domino Michael–Henry reaction [47].
Scheme 29: Asymmetric domino Michael–Henry reaction [48].
Scheme 30: Enantioselective synthesis of derivatives of 3,4-dihydro-2H-pyran 89 [49].
Scheme 31: Asymmetric addition of α,α-dicyano olefins 90 to 3-nitro-2H-chromenes 91 [50].
Scheme 32: Asymmetric three-component reaction producing 2,6-diazabicyclo[2.2.2]octanones 95 [51].
Scheme 33: Asymmetric double Michael reaction producing substituted chromans 99 [52].
Scheme 34: Enantioselective synthesis of multi-functionalized spiro oxindole dienes 106 [53].
Scheme 35: Organocatalyzed Michael aldol cyclization [54].
Scheme 36: Asymmetric synthesis of dihydrocoumarins [55].
Scheme 37: Asymmetric double Michael reaction en route to tetrasubstituted cyclohexenols [56].
Scheme 38: Asymmetric synthesis of α-trifluoromethyl-dihydropyrans 121 [58].
Scheme 39: Tyrosine-derived tertiary amino-thiourea 123 catalyzed Michael hemiaketalization reaction [59].
Scheme 40: Enantioselective entry to bicyclo[3.2.1]octane unit [60].
Scheme 41: Asymmetric synthesis of spiro[4-cyclohexanone-1,3’-oxindoline] 126 [61].
Scheme 42: Kinetic resolution of 3-nitro-2H-chromene 130 [62].
Scheme 43: Asymmetric synthesis of chromanes 136 [63].
Scheme 44: Wang’s utilization of β-unsaturated α-ketoesters 87 [64,65].
Scheme 45: Asymmetric entry to trifluoromethyl-substituted dihydropyrans 144 [66].
Scheme 46: Phenylalanine-derived thiourea-catalyzed domino Michael hemiaketalization reaction [67].
Scheme 47: Asymmetric synthesis of α-trichloromethyldihydropyrans 149 [68].
Scheme 48: Takemoto’s thiourea-catalyzed domino Michael hemiaketalization reaction [69].
Scheme 49: Asymmetric synthesis of densely substituted cyclohexanes [70].
Scheme 50: Enantioselective synthesis of polysubstituted chromeno [4,3-b]pyrrolidine derivatines 157 [71].
Scheme 51: Enantioselective synthesis of spiro-fused cyclohexanone/5-oxazolone scaffolds 162 [72].
Scheme 52: Utilizing 2-mercaptobenzaldehydes 163 in cascade processes [73,74].
Scheme 53: Proposed transition state of the initial sulfa-Michael step [74].
Scheme 54: Asymmetric thiochroman synthesis via dynamic kinetic resolution [75].
Scheme 55: Enantioselective synthesis of thiochromans [76].
Scheme 56: Enantioselective synthesis of chromans and thiochromans synthesis [77].
Scheme 57: Enantioselective sulfa-Michael aldol reaction en route to spiro compounds [78].
Scheme 58: Enantioselective synthesis of 4-aminobenzo(thio)pyrans 179 [79].
Scheme 59: Asymmetric synthesis of tetrahydroquinolines [80].
Scheme 60: Novel asymmetric Mannich–Michael sequence producing tetrahydroquinolines 186 [81].
Scheme 61: Enantioselective synthesis of biologically interesting chromanes 190 and 191 [82].
Scheme 62: Asymmetric tandem Henry–Michael reaction [83].
Scheme 63: An asymmetric synthesis of substituted cyclohexanes via a dynamic kinetic resolution [84].
Scheme 64: Three component-organocascade initiated by Knoevenagel reaction [85].
Scheme 65: Asymmetric Michael reaction catalyzed by catalysts 57 and 211 [86].
Scheme 66: Proposed mechanism for the asymmetric Michael reaction catalyzed by catalysts 57 and 211 [86].
Scheme 67: Asymmetric facile synthesis of hexasubstituted cyclohexanes [87].
Scheme 68: Dual activation catalytic mechanism [87].
Scheme 69: Asymmetric Michael–Michael/aldol reaction catalyzed by catalysts 57, 219 and 214 [88].
Scheme 70: Asymmetric synthesis of substituted cyclohexane derivatives, using catalysts 57 and 223 [89].
Scheme 71: Asymmetric synthesis of substituted piperidine derivatives, using catalysts 223 and 228 [90].
Scheme 72: Asymmetric synthesis of endo-exo spiro-dihydropyran-oxindole derivatives catalyzed by catalyst 232 [91]....
Scheme 73: Asymmetric synthesis of carbazole spiroxindole derivatives, using catalyst 236 [92].
Scheme 74: Enantioselective formal [2 + 2] cycloaddition of enal 209 with nitroalkene 210, using catalysts 23 ...
Scheme 75: Asymmetric synthesis of polycyclized hydroxylactams derivatives, using catalyst 242 [94].
Scheme 76: Asymmetric synthesis of product 243, using catalyst 246 [95].
Scheme 77: Formation of the α-stereoselective acetals 248 from the corresponding enol ether 247, using catalys...
Scheme 78: Selective glycosidation, catalyzed by Shreiner’s catalyst 23 [97].
Graphical Abstract
Figure 1: Different configurations of 1,2-aminoindanol 1a–d.
Scheme 1: Asymmetric F–C alkylation catalyzed by thiourea 4.
Figure 2: Results for the F–C reaction carried out with catalyst 4 and the structurally modified analogues, 4'...
Figure 3: (a) Transition state TS1 originally proposed for the F–C reaction catalyzed by thiourea 4 [18]. (b) Tra...
Scheme 2: Asymmetric F–C alkylation catalyzed by thiourea ent-4 in the presence of D-mandelic acid as a Brøns...
Figure 4: Transition state TS2 proposed for the activation of the thiourea-based catalyst ent-4 by an externa...
Scheme 3: Friedel–Crafts alkylation of indoles catalyzed by the chiral thioamide 6.
Scheme 4: Scalable tandem C2/C3-annulation of indoles, catalyzed by the thioamide ent-6.
Scheme 5: Plausible tandem process mechanism for the sequential, double Friedel–Crafts alkylation, which invo...
Scheme 6: One-pot multisequence process that allows the synthesis of interesting compounds 14. The pharmacolo...
Scheme 7: Reaction pathway proposed for the preparation of the compounds 14.
Scheme 8: The enantioselective synthesis of cis-vicinal-substituted indane scaffolds 21, catalyzed by ent-6.
Scheme 9: Asymmetric domino procedure (Michael addition/Henry cyclization), catalyzed by the thioamide ent-6 ...
Scheme 10: The enantioselective addition of indoles 2 to α,β-unsaturated acyl phosphonates 24, a) screening of...
Figure 5: Proposed transition state TS7 for the Friedel–Crafts reaction of indole and α,β-unsaturated acyl ph...
Scheme 11: Study of aliphatic β,γ-unsaturated α-ketoesters 26 as substrates in the F–C alkylation of indoles c...
Figure 6: Possible transition states TS8 and TS9 in the asymmetric addition of indoles 2 to the β,γ-unsaturat...
Figure 7: Transition state TS10 proposed for the asymmetric addition of dialkylhydrazone 28 to the β,γ-unsatu...
Scheme 12: Different β-hydroxylamino-based catalysts tested in a Michael addition, and the transition state TS...
Scheme 13: Enantioselective addition of acetylacetone (36a) to nitroalkenes 3, catalyzed by 37 and the propose...
Scheme 14: Addition of 3-oxindoles 39 to 2-amino-1-nitroethenes 40, catalyzed by 41.
Scheme 15: Michael addition of 1,3-dicarbonyl compounds 36 to the nitroalkenes 3 catalyzed by the squaramide 43...
Scheme 16: Asymmetric aza-Henry reaction catalyzed by the aminoindanol-derived sulfinyl urea 50.
Figure 8: Results for the aza-Henry reaction carried out with the structurally modified catalysts 50–50''.
Scheme 17: Diels–Alder reaction catalyzed by the aminoindanol derivative ent-41.
Scheme 18: Asymmetric Michael addition of 3-pentanone (55a) to the nitroalkenes 3 through aminocatalysis.
Scheme 19: Substrate scope extension for the asymmetric Michael addition between the ketones 55 and the nitroa...
Scheme 20: A possible reaction pathway in the presence of the catalyst 56 and the plausible transition state T...
Graphical Abstract
Figure 1: Parent and supported bifunctional thioureas used in this work.
Scheme 1: Reaction of nitrostyrene with diethyl malonate and 2-ethoxycarbonyl cyclopentanone.
Scheme 2: Reaction of nitrostyrenes with malonates and β-diketones.
Scheme 3: Reaction of nitrostyrenes with β-keto esters and β-dicarbonyl compounds.
Scheme 4: Reaction of nitrostyrenes with α-nitrocyclohexanone and ethyl α-nitropropionate.
Graphical Abstract
Scheme 1: Organocatalysts screened in the cascade reaction.
Scheme 2: Synthesis of catalyst VIII.
Graphical Abstract
Scheme 1: The mimetic activation mode of Mitsunobu reaction.
Scheme 2: Scale-up of the reaction and deprotection of the product.
Figure 1: The 31P NMR spectra research in CD2Cl2.
Scheme 3: Proposed transition-state model.
Graphical Abstract
Figure 1: Some α-substituted heterocycles for asymmetric catalysis, their reactivity patterns against enoliza...
Figure 2: 1H-Imidazol-4(5H)-ones 1 and thiazol-4(5H)-ones 2.
Scheme 1: a) Synthesis of 2-thio-1H-imidazol-4(5H)-ones [55] and b) preparation of the starting thiohydantoins [59].
Scheme 2: Selected examples of the Michael addition of 2-thio-1H-imidazol-4(5H)-ones to nitroalkenes [55]. aReact...
Scheme 3: Michael addition of thiohydantoins to nitrostyrene assisted by Et3N and catalysts C1 and C3. aAbsol...
Scheme 4: Elaboration of the Michael adducts coming from the Michael addition to nitroalkenes [55].
Figure 3: Proposed model for the Michael addition of 1H-imidazol4-(5H)-ones and selected 1H NMR data which su...
Scheme 5: Michael addition 2-thio-1H-imidazol-4(5H)-ones to the α-silyloxyenone 29 [55].
Scheme 6: Elaboration of the Michael adducts coming from the Michael addition to nitroolefins [55].
Scheme 7: Rhodanines in asymmetric catalytic reactions: a) Reaction with rhodanines of type 44 [78-80]; b) reactions...
Scheme 8: Michael addition of thiazol-4(5H)-ones to nitroolefins promoted by the ureidopeptide-like bifunctio...
Figure 4: Ureidopeptide-like Brønsted bases: catalyst design. a) Previous known design. b) Proposed new desig...
Scheme 9: Ureidopeptide-like Brønsted base bifunctional catalyst preparation. NMM = N-methylmorpholine, THF =...
Scheme 10: Selected examples of the Michael addition of thiazolones to different nitroolefins promoted by cata...
Scheme 11: Elaboration of the Michael adducts to α,α-disubstituted α-mercaptocarboxylic acid derivatives [85].
Scheme 12: Effect of the nitrogen atom at the aromatic substituent of the thiazolone on yield and stereoselect...
Scheme 13: Michael addition reaction of thiazol-4(5H)ones 74 to α’-silyloxyenone 29 [73].
Scheme 14: Elaboration of the thiazolone Michael adducts [73].
Scheme 15: Enantioselective γ-addition of oxazol-4(5H)-ones and thiazol-4(5H)-ones to allenoates promoted by C6...
Scheme 16: Enantioselective γ-addition of thiazol-4(5H)-ones and oxazol-4(5H)-ones to alkynoate 83 promoted by ...
Scheme 17: Proposed mechanism for the C6-catalyzed γ-addition of thiazol-4(5H)-one to allenoates. Adapted from ...
Scheme 18: Catalytic enantioselective α-amination of thiazolones promoted by ureidopeptide like catalysts C5 a...
Scheme 19: Iridium-catalized asymmetric allyllation of substituted oxazol-4(5H)-ones and thiazol-4(5H)-ones pr...
Graphical Abstract
Figure 1: Keramaphidin B (1).
Figure 2: Retrosynthetic analysis of keramaphidin B.
Scheme 1: Enantio- and diastereoselective bifunctional thiourea 12 organocatalysed Michael addition. (a) CO(O...
Scheme 2: Synthesis of bis alkene 5. (a) 12 (20 mol %), toluene, −20 °C, 36 h, 95:5 dr, 92% yield; (b) aq HCH...
Graphical Abstract
Figure 1: Structure of chiral bifunctional organocatalysts.
Figure 2: Proposed stereochemical model.
Scheme 1: Gram scale addition of ketimine 1a and diphenyl phosphonate (2).