Evidence of the Electronic Factor for the Highly Enantioselective Catalytic Efficiency of <i>Cinchona</i>-Derived Phase-Transfer Catalysts
作者:Mi-Sook Yoo、Byeong-Seon Jeong、Jeong-Hee Lee、Hyeung-geun Park、Sang-sup Jew
DOI:10.1021/ol050123u
日期:2005.3.1
evaluated as phase-transfercatalysts in the enantioselective alkylation of glycine imine ester 1. The N-oxypyridine and cyanobenzene moieties might play an important role to form a rigid conformation by coordinating with H(2)O via hydrogen bonding leading to high enantioselectivity (97 approximately >99% ee), which provides evidence of an electronic factor for the high enantioselective catalytic efficiency
An Unusual Electronic Effect of an Aromatic-F in Phase-Transfer Catalysts Derived from <i>Cinchona</i>-Alkaloid
作者:Sang-sup Jew、Mi-Sook Yoo、Byeong-Seon Jeong、Il Yeong Park、Hyeung-geun Park
DOI:10.1021/ol0267679
日期:2002.11.1
factors in the catalytic enantioselective phase-transfer alkylation of glycine anion equivalent. An ortho-fluoro substituent on the benzyl group in the quaternary ammonium salt dramatically increased the enantioselectivity in the alkylation. O(9)-Allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide (27), which gave the highest enantioselectivity of the catalysts studied, was used to prepare 12 alpha-alkylated
Synthesis and application of dimeric Cinchona alkaloid phase-transfer catalysts: α,α′-bis[O(9)-allylcinchonidinium]-o, m, or p-xylene dibromide
作者:Sang-sup Jew、Byeong-Seon Jeong、Mi-Sook Yoo、Hoon Huh、Hyeung-geun Park
DOI:10.1039/b102584h
日期:——
A dimeric Cinchona alkaloid ammonium salt,
α,αâ²-bis[O(9)-allylcinchonidinium]-m-x
ylene dibromide 4, has been developed as a new efficient phase-transfer
catalyst; the catalytic enantioselective alkylation of
N-(diphenylmethylene)glycine tert-butyl ester using 4
provided 7 in a high enantiomeric excess (90â99% ee).
The Enantioselective Synthesis of α-Amino Acid Derivatives via Organoboranes
作者:Martin J. O'Donnell、Mark D. Drew、Jeremy T. Cooper、Francisca Delgado、Changyou Zhou
DOI:10.1021/ja017522e
日期:2002.8.1
Optically active (S)-α-amino acids are prepared in 54−95% ee (12 cases) by reaction of the Schiff base acetate of glycine tert-butyl ester with B-alkyl-9-BBN derivatives in the presence of the Cinc...
通过甘氨酸叔丁酯的席夫碱乙酸酯与 B-烷基-9-BBN 衍生物在 Cinc 存在下反应,以 54-95% ee(12 例)制备光学活性 (S)-α-氨基酸...
Phase-transfer-catalyzed Asymmetric Alkylation with Epoxy Triflates as Alkylating Agents: Highly Stereoselective Synthesis of γ,δ-Epoxy-α-amino Acids
作者:Satoru Arimitsu、Daisuke Kato、Keiji Maruoka
DOI:10.1246/cl.2011.1115
日期:2011.10.5
Although alkyl sulfonates are commonly used for alkylating agents, there are very few reports on phase-transfer-catalyzed asymmetric alkylation with alkyl sulfonates. Herein, we report that the asy...