Chiral Octahedral Complexes of Cobalt(III) as “Organic Catalysts in Disguise” for the Asymmetric Addition of a Glycine Schiff Base Ester to Activated Olefins
作者:Victor I. Maleev、Michael North、Vladimir A. Larionov、Ivan V. Fedyanin、Tatyana F. Savel'yeva、Margarita A. Moscalenko、Alexander F. Smolyakov、Yuri N. Belokon
DOI:10.1002/adsc.201400091
日期:2014.5.26
complexes of cobalt(III) prepared from Schiff bases derived from chiral diamines and salicylaldehydes were shown to be efficient catalysts of the benchmark asymmetric phase‐transfer Michael addition of nine activated olefins to O’Donnell’s substrate. The reaction products had enantiomeric purities of up to 96%. DFT calculations were invoked to rationalize the stereochemistry of the addition.
Stereochemically defined C-substituted glutamic acids and their derivatives. 1. An efficient asymmetric synthesis of (2S,3S)-3-methyl- and -3-trifluoromethylpyroglutamic acids
作者:Vadim A Soloshonok、Chaozhong Cai、Victor J Hruby、Luc Van Meervelt、Nikolai Mischenko
DOI:10.1016/s0040-4020(99)00711-5
日期:1999.10
An efficient asymmetricsynthesis of biologically important (2S,3S)-3-methyl- and (2S,3S)-3-trifluoromethylpyroglutamic acid has been developed. The method consists of diastereoselective Michael addition reaction between ethyl crotonate or ethyl 4,4,4-trifluorocrotonate and a Ni(II) complex of the chiral non-racemic Schiff base of glycine with (S)-o-[N-(N-benzylprolyl)amino]benzophenone (BPB) followed
Ethyl trans-3-(trifluoromethyl)pyroglutamate 1 is synthesized in excellent yield; racemic 1 is enzymatically resolved with α-chymotrypsin-catalyzed hydrolysis affording both the enantiomerically pure enantiomers. The absolute configuration is established by X-ray analysis of the corresponding trichloroethylester.
Synthesis of pure enantiomers of cis- and trans-3-(trifluoromethyl) pyroglutamic esters
作者:Detlef Gestmann、André J. Laurent、Eliane G. Laurent
DOI:10.1016/s0022-1139(96)03455-0
日期:1996.9
hydrolysis gives the cis/trans-3-(trifluoromethyl) pyroglutamates. The enantiomericallypure Schiff base, prepared from chiral 2-hydroxy-3-pinanone and t-butyl glycinate, reacts with trans-ethyl-4,4,4-trifluorocrotonate to produce four diastereoisomers which may be separated and hydrolysed to give enantiomericallypurecis- and trans-3-(trifluoromethyl)pyroglutamate.