Enantiospecific Synthesis of <i>N</i>-(9-Phenylfluoren-9-yl)-α-amino Ketones

Abstract

Enantiomerically pure N-(9-phenylfluoren-9-yl)-α-amino ketones were prepared in excellent yields by acylation of organolithium reagents with N-(9-phenylfluoren-9-yl)-α-amino acid-derived oxazolidinones. The method is not applicable for the acylation of Grignard reagents as they attack the methylenic carbon of the oxazolidinone to give the corresponding N-alkylated amino acids 13 in excellent yields. The resulting N-(9-phenylfluoren-9-yl)-α-amino ketones 8 could be stereoselectively reduced to the corresponding syn- or anti-β-amino alcohols depending upon the nature of the reducing agent.