New polymer-supported chiral phase-transfer catalysts in the asymmetric synthesis of alpha-amino acids: the role of a spacer

摘要

Polymer-supported cinchona alkaloid salts with different spacers were used as phase-transfer catalysts in the asymmetric C-alkylation of N-diphenyl methylene glycine tert-butyl ester. Various catalysts and alkylation conditions were studied, the best result being 81% e.e. with cinchoninium iodide bound to polqstyrene with a four-carbon spacer. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 16]