Xiaofeng Liu1, Bingfeng Sun, Li Deng. 1. Department of Chemistry, Brandeis University, 415 South St., Waltham, MA 02454-9110, USA, Fax +01 781 736 2516; E-mail: deng@brandeis.edu.
Abstract
Highly enantioselective aminations of acyclic α-alkyl β-keto thioesters and trifluoroethyl α-methyl α-cyanoacetate (12) with as low as 0.05 mol % of a bifunctional cinchona alkaloid catalyst were established. This ability to afford highly enantioselectivity for the amination of α-alkyl β-carbonyl compounds renders the 6'-OH cinchona alkaloid-catalyzed amination applicable for the enantioselective synthesis of acyclic chiral compounds bearing N-substituted quaternary stereocenters. The synthetic application of this reaction is illustrated in a concise asymmetric synthesis of α-methylserine, a key intermediate previously utilized in the total synthesis of a small molecule immunomodulator, conagenin.
Highly enantioselective aminations of acyclic α-alkyl β-keto thioesters and trifluoroethyl α-methyl α-cyanoacetate (12) with as low as 0.05 mol % of a bifunctional cinchona alkaloid catalyst were established. This ability to afford highly enantioselectivity for the amination of α-alkyl β-carbonyl compounds renders the n class="Chemical">6'-OH cinchona alkaloid-catalyzed amination applicable for the enantioselective synthesis of acyclic chiral compounds bearing N-substituted quaternary stereocenters. The synthetic application of this reaction is illustrated in a concise asymmetric synthesis of α-methylserine, a key intermediate previously utilized in the total synthesis of a small molecule immunomodulator, conagenin.
Authors: T Yamashita; M Iijima; H Nakamura; K Isshiki; H Naganawa; S Hattori; M Hamada; M Ishizuka; T Takeuchi; Y Iitaka Journal: J Antibiot (Tokyo) Date: 1991-05 Impact factor: 2.649