New trimeric quaternary ammonium salts derived from cinchonine or cinchonidine bridging N,N'-bis(ethyl)-4-(methyl)-phenyl-amine moiety are used as a chiral phase transfer catalysts for the asymmetric alkylation of a N-(diphenylmethylene)glycine tert-butyl ester with very good chemical yield (up to 97%) and ee's (up to 98%). (c) 2005 Elsevier B.V. All rights reserved.