Design, synthesis, and optical resolution of a novel non-natural chiral auxiliary, 1-(2,5-dimethoxyphenyl)ethylamine. Application to diastereoselective alkylation of aldimines

A chiral amine; 1-(2,5-dimethoxyphenyl)ethylamine, was found to be an effec tive chiral auxiliary for the diastereoselective alkylation of its aldimine s with alkylmetals. The 1-(2,5-dimethoxyphenyl)ethyl group of the chiral au xiliary could be removed by the acetylation and then oxidation of the resul tant alkylated product, accompanying an amino-transfer from the chiral auxi liary to the final product. Racemic 1-(2,5-dimethoxyphenyl)ethylamine could be easily synthesized from 1,4-dimethoxybenzene and resolved by the diaste reomeric salt formation with mandelic acid to give both enantiomers in pure forms. (C) 1999 Elsevier Science Ltd. All rights reserved.