Highly Enantioselective Synthesis of (<i>S</i>)-α-Alkyl-α,β-diaminopropionic Acids via Asymmetric Phase-Transfer Catalytic Alkylation of 2-Phenyl-2-imidazoline-4-carboxylic Acid<i>tert</i>-Butyl Esters
作者:Yohan Park、Sukhoon Kang、Young Ju Lee、Taek-Soo Kim、Byeong-Seon Jeong、Hyeung-geun Park、Sang-sup Jew
DOI:10.1021/ol9013552
日期:2009.8.20
An efficient enantioselective synthetic method for (S)-α-alkyl-α,β-diaminopropionic acid is reported. The asymmetricphase-transfercatalyticalkylation of N(1)-Boc-2-phenyl-2-imidazoline-4-carboxylic acid tert -butyl ester in the presence of chiral quaternary ammonium catalyst gave the corresponding alkylated products (93−98% ee) which could be transformed to enantioenriched α-alkyl-α,β-diaminopropionic
Diastereoselective Electrophilic Amination of Chiral 1-Benzoyl-2,3,5,6-tetrahydro-3-methyl-2-(1-methylethyl)pyrimidin-4(1H)-one for the Asymmetric Syntheses ofα-Substitutedα,β-Diaminopropanoic Acids
The chiral compounds (R)- and (S)-1-benzoyl-2,3,5,6-tetrahydro-3-methyl-2-(1-methylethyl)pyrimidin-4(1H)-one ((R)- and (S)-1), derived from (R)- and (S)-asparagine, respectively, were used as convenient starting materials for the preparation of the enantiomerically pure α-alkylated (alkyl=Me, Et, Bn) α,β-diamino acids (R)- and (S)-11–13. The chiral lithium enolates of (R)- and (S)-1 were first alkylated
Stereoselective amination of chiral enolates: Synthesis of chiral key intermediates for β-lactam antibiotics
作者:Carlos Cativiela、María D. Díaz-de-Villegas、José A. Galvéz
DOI:10.1016/0957-4166(94)80114-2
日期:1994.8
Stereoselective enolate trapping of lithium (1S, 2R, 4R)- 10-dicyclohexylsulfamoylisobornyl-2-cyano-3-phenylpropanoate with O-(diphenylphosphinyl) hydroxylamine followed by appropriate reduction, hydrolysis, and cyclisation processes allows the asymmetric synthesis of (S)-3-amino-3-benzyl-2-azetidinone.