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

A general procedure was developed to prepare α-BOC-aminoketones in good yields from α-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.