A stereocontrolled synthesis of monofluoro ketomethylene dipeptide isosteres

A simple, stereocontrolled synthesis of monofluoro ketomethylene dipeptide isosteres has been developed. N-Tritylated ketomethylene dipeptide isostere s, prepared from N-tritylated amino acids, are converted to their Z-TMS eno l ethers and fluorinated with Selectfluor. There is cooperative stereocontr ol between the N-tritylamine group and the alkyl group at C-2. The method i s short (six steps), diastereoselective (85 --> 95%), and enantioselective (> 95%).