A novel enantioselective synthesis of alpha-azido ketones

The asymmetric synthesis of a range of a-azido ketones 5a-e is described. K ey step of the procedure is the diastereo- and enantioselective nucleophili c substitution of an iodo group in alpha'-silylated cc-iodo ketones 3a-e wi th NaN3w (de = 90-greater than or equal to 95%, ee greater than or equal to 95%). Subsequent racemization free carbon-silicon bond cleavage using 3HF . Et3N gives the corresponding alpha-azido ketones 5a-e in good yield (54-8 6%) with high enantiomeric excesses (ee = 90-greater than or equal to 95%).