Improved syntheses of α-BOC-aminoketones from α-BOC-amino-Weinreb amides using a pre-deprotonation protocol

A general procedure was developed to prepare alpha-BOC-aminoketones in good yields from alpha-BOC-amino Weinreb amides containing an exchangeable amino proton. By first deprotonating this amino group using 1 equiv. of a simple alkyl Grignard base, only a stoichiometric amount, rather than a large excess, of the nucleophile was needed to prepare the ketone. This procedure is therefore more economical to run and the purification is easier. (C) 2002 Elsevier Science Ltd. All rights reserved.