BASE-PROMOTED REACTIONS OF ALPHA-AZIDO KETONES WITH ALDEHYDES AND KETONES - A NOVEL ENTRY TO ALPHA-AZIDO-BETA-HYDROXY KETONES AND 2,5-DIHYDRO-5-HYDROXYOXAZOLES

The base-promoted reaction of alpha-azido ketones with aldehydes and k etones provides a new and simple route to either alpha-azido-beta-hydr oxy ketones, which are valuable 1,2,3-trifunctionalized synthons, or 2 ,5-dihydro-5-hydroxyoxazoles, which are a little known type of oxazoli ne. These two products are formed by the electrophilic trapping of two different anions that are produced sequentially during the reaction, The alpha-azido-beta-hydroxy ketones are formed by an aldol reaction b etween an enolate of the alpha-azidoketone and an aldehyde. The 2,5-di hydro-5-hydroxyoxazoles are formed by electrophilic trapping of an imi no anion which is produced by nitrogen loss from the cx-azido ketone e nolate.