Synthesis of Fmoc-protected 4-carboxydifluoromethyl-L-phenylalanine: A phosphotyrosyl mimetic of potential use for signal transduction studies

4-(Carboxymethyl)phenylalanine (2) and its alpha,alpha-difluoro homologue 4 -(carboxydifluoromethyl)-phenylalanine (3) have been described as phosphoty rosyl mimetics. Herein we report the synthesis of N-Fmoc 4-(0-tert-butyl ca rboxymethyl)-phenylalanine (4) and N-Fmoc 4-(0-tert-butyl carboxydifluorome thyl)phenylalanine (5) in high enantiomeric purity. These analogues bear or thogonal protection suitable for the preparation of inhibitors directed aga inst a variety of signal transduction pathways, including SH2 and PTP domai ns and protein-tyrosine phosphatases. Published by Elsevier Science Ltd.