Iodolactonization of 3-amino-4-pentenoic acid: a stereoselective synthesisof syn-gamma-hydroxy-beta-amino acids

The reaction of (S)-3-N-Cbz-4-pentenoic acid with iodine in acetonitrile in the presence of AgOTf gave the cis-iodo-lactone 6 in excellent yield and i n a highly diastereoselective manner. The substitutions of the iodine in 6 by different Grignard reagents in the presence of CuI and the subsequent co nversions into the functionalized syn-gamma-hydroxy-beta-amino acids have b een investigated. By the above reaction sequence, (3S,4S)-3-amino1-4-hydrox y-5-cyclohexyl pentanoic acid was synthesized with high enantioselectivity. (C) 2000 Elsevier Science Ltd. All rights reserved.