Alkylation of N '-[(S)-1 '-phenylethyl]-N-(diphenylmethylene)glycinamide using a phase transfer catalyst (PTC) for practical asymmetric syntheses of alpha-amino acid derivatives

摘要

The chiral auxiliary mediated stereoselective alkylation reaction of N'[(S)-1'-phenylethyl]-N-(diphenylmethylene)glycinamide (1) using a phase transfer catalyst (PTC) is described. Alkylation of 1 using 18-crown-6 as a PTC for liquid-solid extraction of KOH in toluene gives best results. This methodology provides a practical protocol for the preparation of a variety of enantio-enriched unnatural alpha -amino acid derivatives up to 83:17 enantiomeric ratio. [References: 21]