Preparation and assignment of configuration of 1-benzoyl- (2S)-tert-butyl-3-methyl-perhydropyrimidin-4-one. Useful starting material for the enantioselective synthesis of α-substituted β-amino acids
摘要:
(S) -Asparagine, an inexpensive beta-amino acid was converted into the title heterocycle (+)-1 in very good overall yield. The highly selective trans methylation of (+)-1-Li, and the hydrolysis of the resulting adduct afforded (R)-alpha-methyl-beta-alanine, allowing the assignment of the (S) configuration in (+)-1.
Enantioselective synthesis of β-amino acids. 7. Preparation of enantiopure α-substituted β-amino acids from 1-benzoyl-2(S)-tert-butyl-3-methylperhydropyrimidin-4-one.1,2
Inexpensive natural α-amino acid L-asparagine was efficiently converted to either (R)- or (S)-α-alkylated β-amino acids in enantiomerically pure state. The key intermediate in this protocol is the enantiopure N,N-acetal pyrimidinone (S)-1, a masked chiral derivative of β-alanine.
Self-reproduction of chirality. Asymmetric synthesis of .beta.-aryl-.beta.-amino acids from enantiomerically pure dihydropyrimidinones
作者:Joseph P. Konopelski、Kent S. Chu、George R. Negrete
DOI:10.1021/jo00004a005
日期:1991.2
Enantiomerically pure dihydropyrimidinone 1 reacts with aryl iodides in the presence of catalytic amounts of Pd(OAc)2 and added phosphine to afford dihydropyrimidinone 4, in which a formal conjugate addition of the aryl group to the alpha,beta-unsaturated system has occurred. Application of this methodology to the synthesis of a protected version of the tripeptide portion of the natural product jasplakinolide is presented.