51
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Wang Z, Chen Z, Bai S, Li W, Liu X, Lin L, Feng X. Highly Z-Selective Asymmetric Conjugate Addition of Alkynones with Pyrazol-5-ones Promoted by N,N′-Dioxide-Metal Complexes. Angew Chem Int Ed Engl 2012; 51:2776-9. [DOI: 10.1002/anie.201109130] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Indexed: 11/09/2022]
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52
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Wang Z, Chen Z, Bai S, Li W, Liu X, Lin L, Feng X. Highly Z-Selective Asymmetric Conjugate Addition of Alkynones with Pyrazol-5-ones Promoted by N,N′-Dioxide-Metal Complexes. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201109130] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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53
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Waser M, Gratzer K, Herchl R, Müller N. Design, synthesis, and application of tartaric acid derived N-spiro quaternary ammonium salts as chiral phase-transfer catalysts. Org Biomol Chem 2011; 10:251-4. [PMID: 22038391 DOI: 10.1039/c1ob06573d] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel class of tartaric acid-derived N-spiro quaternary ammonium salts was synthesised starting from known TADDOLs. These compounds were found to catalyse the asymmetric α-alkylation of glycine Schiff bases with high enantioselectivities and in good yields.
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Affiliation(s)
- Mario Waser
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstraße 69, 4040 Linz, Austria.
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54
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Shi CL, Chen H, Shi D. An efficient one-pot three-component synthesis of tetrahydrofuro[3,4-b]quinoline-1,8(3H,4H)-dione derivatives catalyzed by L-proline. J Heterocycl Chem 2011. [DOI: 10.1002/jhet.782] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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55
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56
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Jiang L, Lei Q, Huang X, Cui HL, Zhou X, Chen YC. Lewis Base Assisted Brønsted Base Catalysis: Direct Regioselective Asymmetric Vinylogous Alkylation of Allylic Sulfones. Chemistry 2011; 17:9489-93. [DOI: 10.1002/chem.201100534] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Indexed: 11/09/2022]
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57
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Heravi MM, Zakeri M, Mohammadi N. Morpholine Catalyzed One-pot Multicomponent Synthesis of Compounds Containing Chromene Core in Water. CHINESE J CHEM 2011. [DOI: 10.1002/cjoc.201190217] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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58
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Misaki T, Kawano K, Sugimura T. HighlyZ-Selective Asymmetric 1,4-Addition Reaction of 5H-Oxazol-4-ones with Alkynyl Carbonyl Compounds Catalyzed by Chiral Guanidines. J Am Chem Soc 2011; 133:5695-7. [DOI: 10.1021/ja200283n] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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59
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Nielsen M, Jacobsen CB, Jørgensen KA. Asymmetric Organocatalytic Electrophilic Phosphination. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201007188] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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60
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Nielsen M, Jacobsen CB, Jørgensen KA. Asymmetric organocatalytic electrophilic phosphination. Angew Chem Int Ed Engl 2011; 50:3211-4. [PMID: 21432953 DOI: 10.1002/anie.201007188] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Indexed: 11/05/2022]
Affiliation(s)
- Martin Nielsen
- Center for Catalysis, Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
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61
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Lian M, Li Z, Du J, Meng Q, Gao Z. Asymmetric Direct α-Hydroxylation of β-Oxo Esters by Phase-Transfer Catalysis Using Chiral Quaternary Ammonium Salts. European J Org Chem 2010. [DOI: 10.1002/ejoc.201001175] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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62
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Guo S, Yuan Y. One-Pot Synthesis of 1,4-Dihydropyridine and Polyhydro-quinoline Derivatives via L-Proline Catalyzed Hantzsch Multicomponent Reaction under Ultrasound Irradiation. CHINESE J CHEM 2010. [DOI: 10.1002/cjoc.201090151] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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63
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Moss T, Alonso B, Fenwick D, Dixon D. Catalytic Enantio- and Diastereoselective Alkylations with Cyclic Sulfamidates. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200905329] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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64
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Wang X, Lan Q, Shirakawa S, Maruoka K. Chiral bifunctional phase transfer catalysts for asymmetric fluorination of β-keto esters. Chem Commun (Camb) 2010; 46:321-3. [DOI: 10.1039/b920099a] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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65
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Moss T, Alonso B, Fenwick D, Dixon D. Catalytic Enantio- and Diastereoselective Alkylations with Cyclic Sulfamidates. Angew Chem Int Ed Engl 2009; 49:568-71. [DOI: 10.1002/anie.200905329] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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66
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Terada M, Tsushima D, Nakano M. Enantioselective Electrophilic Amination of α-Cyanothioacetates with Azodicarboxylates Catalyzed by an Axially Chiral Guanidine Base. Adv Synth Catal 2009. [DOI: 10.1002/adsc.200900594] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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67
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Chen D, Chen Z, Xiao X, Yang Z, Lin L, Liu X, Feng X. Highly Enantioselective Michael Addition of Malonate Derivatives to Enones Catalyzed by anN,N′-Dioxide-Scandium(III) Complex. Chemistry 2009; 15:6807-10. [DOI: 10.1002/chem.200901157] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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68
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Gioia C, Fini F, Mazzanti A, Bernardi L, Ricci A. Organocatalytic Asymmetric Formal [3 + 2] Cycloaddition with in Situ-Generated N-Carbamoyl Nitrones. J Am Chem Soc 2009; 131:9614-5. [DOI: 10.1021/ja902458m] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Claudio Gioia
- Department of Organic Chemistry “A. Mangini”, University of Bologna, viale Risorgimento 4, 40136 Bologna, Italy
| | - Francesco Fini
- Department of Organic Chemistry “A. Mangini”, University of Bologna, viale Risorgimento 4, 40136 Bologna, Italy
| | - Andrea Mazzanti
- Department of Organic Chemistry “A. Mangini”, University of Bologna, viale Risorgimento 4, 40136 Bologna, Italy
| | - Luca Bernardi
- Department of Organic Chemistry “A. Mangini”, University of Bologna, viale Risorgimento 4, 40136 Bologna, Italy
| | - Alfredo Ricci
- Department of Organic Chemistry “A. Mangini”, University of Bologna, viale Risorgimento 4, 40136 Bologna, Italy
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69
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Fang L, Lin A, Hu H, Zhu C. Highly Enantioselective Sulfenylation of β-Ketoesters: H-Bond Acceptor Catalysis. Chemistry 2009; 15:7039-43. [DOI: 10.1002/chem.200901099] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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70
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Chen Z, Furutachi M, Kato Y, Matsunaga S, Shibasaki M. A Stable Homodinuclear Biscobalt(III)-Schiff Base Complex for Catalytic Asymmetric 1,4-Addition Reactions of β-Keto Esters to Alkynones. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200805967] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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71
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Chen Z, Furutachi M, Kato Y, Matsunaga S, Shibasaki M. A Stable Homodinuclear Biscobalt(III)-Schiff Base Complex for Catalytic Asymmetric 1,4-Addition Reactions of β-Keto Esters to Alkynones. Angew Chem Int Ed Engl 2009; 48:2218-20. [DOI: 10.1002/anie.200805967] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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72
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Poulsen T, Dickmeiss G, Overgaard J, Jørgensen K. Organocatalytic Asymmetric Synthesis of Versatile γ-Lactams. Angew Chem Int Ed Engl 2008; 47:4687-90. [DOI: 10.1002/anie.200800329] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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73
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Poulsen T, Dickmeiss G, Overgaard J, Jørgensen K. Organocatalytic Asymmetric Synthesis of Versatile γ-Lactams. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200800329] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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74
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Affiliation(s)
- Keiji Maruoka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
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75
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Kumar A, Maurya RA. Organocatalysed three-component domino synthesis of 1,4-dihydropyridines under solvent free conditions. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.02.022] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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76
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Elsner P, Bernardi L, Salla GD, Overgaard J, Jørgensen KA. Organocatalytic Asymmetric Conjugate Addition to Allenic Esters and Ketones. J Am Chem Soc 2008; 130:4897-905. [DOI: 10.1021/ja710689c] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Petteri Elsner
- Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Luca Bernardi
- Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Giorgio Dela Salla
- Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Jacob Overgaard
- Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Karl Anker Jørgensen
- Danish National Research Foundation, Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark
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77
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A novel and efficient one-pot synthesis of furo[3′,4′:5,6]pyrido[2,3-c]pyrazole derivatives using organocatalysts. Tetrahedron 2008. [DOI: 10.1016/j.tet.2007.12.053] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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78
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Alemán J, Jacobsen CB, Frisch K, Overgaard J, Jørgensen KA. Organocatalytic asymmetric vinylogous addition to quinones – formation of optically active α-aryl ketones. Chem Commun (Camb) 2008:632-4. [DOI: 10.1039/b716485h] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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79
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Paixão MW, Nielsen M, Jacobsen CB, Jørgensen KA. Organocatalytic asymmetric ring-opening of aziridines. Org Biomol Chem 2008; 6:3467-70. [DOI: 10.1039/b812369a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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80
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Kim H, MacMillan DWC. Enantioselective Organo-SOMO Catalysis: The α-Vinylation of Aldehydes. J Am Chem Soc 2007; 130:398-9. [DOI: 10.1021/ja077212h] [Citation(s) in RCA: 211] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hahn Kim
- Merck Center for Catalysis at Princeton University, Princeton, New Jersey 08544
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81
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Hashimoto T, Maruoka K. Recent Development and Application of Chiral Phase-Transfer Catalysts. Chem Rev 2007; 107:5656-82. [DOI: 10.1021/cr068368n] [Citation(s) in RCA: 652] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takuya Hashimoto
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
| | - Keiji Maruoka
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502 Japan
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82
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Esteban J, Costa AM, Gómez À, Vilarrasa J. Michael Addition−Elimination Reactions of Chiral Enolates with Ethyl 3-Halopropenoates. Org Lett 2007; 10:65-8. [DOI: 10.1021/ol702632m] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jorge Esteban
- Departament de Química Orgànica, Facultat de Química, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Catalonia, Spain
| | - Anna M. Costa
- Departament de Química Orgànica, Facultat de Química, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Catalonia, Spain
| | - Àlex Gómez
- Departament de Química Orgànica, Facultat de Química, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Catalonia, Spain
| | - Jaume Vilarrasa
- Departament de Química Orgànica, Facultat de Química, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Catalonia, Spain
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83
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Lian XZ, Huang Y, Li YQ, Zheng WJ. A Green Synthesis of Tetrahydrobenzo[b]pyran Derivatives through Three-Component Condensation Using N-Methylimidazole as Organocatalyst. MONATSHEFTE FUR CHEMIE 2007. [DOI: 10.1007/s00706-007-0706-2] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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84
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Capuzzi M, Perdicchia D, Jørgensen K. Highly Enantioselective Approach to Geminal Bisphosphonates by Organocatalyzed Michael-Type Addition of β-Ketoesters. Chemistry 2007; 14:128-35. [DOI: 10.1002/chem.200701317] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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85
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Marianacci O, Micheletti G, Bernardi L, Fini F, Fochi M, Pettersen D, Sgarzani V, Ricci A. Organocatalytic Asymmetric Mannich Reactions withN-Boc andN-Cbz Protected α-Amido Sulfones (Boc:tert-Butoxycarbonyl, Cbz: Benzyloxycarbonyl). Chemistry 2007; 13:8338-51. [PMID: 17705329 DOI: 10.1002/chem.200700908] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Different malonates and beta-ketoesters can react with N-tert-butoxycarbonyl- (N-Boc) and N-benzyloxycarbonyl- (N-Cbz) protected alpha-amido sulfones in an organocatalytic asymmetric Mannich-type reaction. The reaction makes use of a simple and easily obtained phase-transfer catalyst and proceeds under very mild and user-friendly conditions. The optimised protocol avoids the preparation and the isolation of the relatively unstable N-Boc and N-Cbz imines that are generated in situ from the bench-stable alpha-amido sulfones. The corresponding Mannich bases are generally obtained in good yields and enantioselectivities, and can be readily transformed into key compounds, such as optically active beta3-amino acids in one easy step. Enantioenriched N-Boc and N-Cbz protected beta-amino acids that are suitable for peptide synthesis are also available from the Mannich adducts through simple manipulations. Control experiments showed the dual role of the enolate-catalyst ion pair in this reaction, as well as the crucial role of the presence of water to achieve high enantioselectivities.
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Affiliation(s)
- Olindo Marianacci
- Department of Organic Chemistry A. Mangini, Faculty of Industrial Chemistry, University of Bologna, V. Risorgimento 4, 40136 Bologna, Italy
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86
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Kumar A, Maurya RA. Bakers’ yeast catalyzed synthesis of polyhydroquinoline derivatives via an unsymmetrical Hantzsch reaction. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.03.130] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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87
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88
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Synthesis of polyhydroquinoline derivatives through unsymmetric Hantzsch reaction using organocatalysts. Tetrahedron 2007. [DOI: 10.1016/j.tet.2006.12.074] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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89
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Santoro S, Poulsen TB, Jørgensen KA. Enantioselective organocatalytic substitution of α-cyanoacetates on imidoyl chlorides – synthesis of optically active ketimines. Chem Commun (Camb) 2007:5155-7. [DOI: 10.1039/b715810f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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90
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Alemán J, Reyes E, Richter B, Overgaard J, Jørgensen KA. Organocatalytic asymmetric “anti-Michael” reaction of β-ketoesters. Chem Commun (Camb) 2007:3921-3. [PMID: 17896033 DOI: 10.1039/b710393j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first organocatalytic "anti-Michael" reaction of cyclic-beta-ketoesters to unsaturated double bonds is described in a highly asymmetric version leading to the synthesis of alpha,alpha'-disubstituted branched double bonds as optically active Baylis-Hillman-like adducts.
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Affiliation(s)
- José Alemán
- Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, DK-8000, Aarhus C, Denmark
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91
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Poulsen TB, Bernardi L, Aleman J, Overgaard J, Jørgensen KA. Organocatalytic Asymmetric Direct α-Alkynylation of Cyclic β-Ketoesters. J Am Chem Soc 2006; 129:441-9. [PMID: 17212424 DOI: 10.1021/ja067289q] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The first organocatalytic enantioselective direct alpha-alkynylation of beta-ketoesters and 3-acyl oxindoles is described. It is demonstrated that activated beta-halo-alkynes undergo nucleophilic acetylenic substitution catalyzed by chiral phase-transfer compounds to afford the alkynylated products in high yields and excellent enantioselectivities. The potential of the reaction is first demonstrated for various alkynylating reagents having chloride and bromide as the leaving groups and substituents such as allyl and alkyl esters, amides, ketones, and sulfones. These reactions proceed with 74-99% yield and 88-97% ee. Then the scope in nucleophile is demonstrated for a large number of cyclic beta-ketoesters with various ring-sizes and for oxindoles as well. The corresponding optically active products are formed in high yields and with enantioselectivities up to 98% ee. The procedure allows for the stereocontrolled attachment of an ethynyl unit in the alpha-position to the carbonyl compound by facile removal of the activating group, and this has been demonstrated for a number of the optically active allyl esters. Furthermore, the synthesis of optically active 1,4-enynes is also shown. The isolation and characterization by X-ray analysis of the catalyst with p-nitrophenolate as the counterion allowed us to propose a model of the catalyst-substrate intermediate which might account for the observed enantioselectivity of the organocatalytic enantioselective alpha-alkynylation reaction. Furthermore, it is suggested that this intermediate is also the reactive species for a number of other electrophiles adding to beta-ketoesters giving enantioselectivities in the range of 90-98% ee.
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Affiliation(s)
- Thomas B Poulsen
- Department of Chemistry, Center for Catalysis, Danish National Research Foundation, Aarhus University, DK-8000 Aarhus C, Denmark
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