Asymmetric synthesis of non-natural amino acid derivatives: (2R/3S) and (2S/3R) 2-(tert-butoxycarbonylamino)-3-cyclohexyl-3-phenyl propanoic acids

摘要

Highly conformationally-constrained novel alpha-amino acid derivatives ((2R/3S) and (2S/3R)-2-(tert-butoxycarbonylamino)-3cyclohexyl-3-phenylpropanoic acids) have been synthesised with high stereoselectivity (>90% de) and in 36-37% overall yields. In the synthesis, Evans' auxiliary (4(R/S)-4-phenyl-oxzaolidin-2-one) was used to control the stereoselectivity via the key reactions of asymmetric Michael addition, azidation and catalytic hydrogenolysis.