The stereochemical course of addition of allyltrimethylsilane to protected L-alaninals and L-serinals in the presence of Lewis acids. Total synthesis of cis-(2R,3S)-3-hydroxyproline

摘要

The influence of Lewis acids on the diastereoselectivity of the addition of allyltrimethylsilane to variously protected L-alaninals and L-serinals was investigated and high levels of asymmetric induction were achieved. Stereochemical models for rationalisation of the results obtained are proposed. cis-(2R,3S)-3-Hydroxyproline was synthesised starting from N-Cbz,O-TBS-L-serinal, in which the crucial step involves addition of allyltrimethylsilane to the aldehyde in the presence of SnCl4. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 34]