Counter-rotatable dual cinchona quinuclidinium salts and their phase transfer catalysis in enantioselective alkylation of glycine imines
作者:Jiin Oh、Jihyeon Park、Keepyung Nahm
DOI:10.1039/d1cc02785a
日期:——
Dual cinchona quinuclidinium salts with a diphenyl ether linker were synthesized and used as powerful asymmetric phasetransfer catalysts in the α-alkylation of imines of glycine and alanine ester with 0.01–0.1 mol% loading (17 examples, 92–99% ee). Skewed conformers of dual quinuclidiniums at TS were proposed to rationalize their high efficiency via DFT calculations.
Design of new, chiral phase-transfer catalysts for practical, catalytic asymmetric synthesis
作者:Keiji Maruoka
DOI:10.1016/s0022-1139(01)00472-9
日期:2001.11
Structurally rigid, chiral spiro ammonium salts of type 1 derived from commercially available (S)-binaphthol have been designed as a new C2-symmetricchiralphase-transfercatalyst and successfully applied to the highly efficient, catalytic enantioselective alkylation of tert-butyl glycinate Schiff base under mild phase-transfer conditions to furnish α-alkyl-α-amino acids and α,α-dialkyl-α-amino acids with excellent
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).
In this paper, we describe investigations into the use of cinchona alkaloid-derived quaternary ammonium phase-transfercatalysts for the asymmetric alkylation of a benzophenone-derived glycine-imine. Utility of this process is demonstrated by the enantioselectivesynthesis of a range of α-aminoacid esters.