A NEW SYNTHESIS OF HIGHLY FUNCTIONAL NITRONES THROUGH A NITROSOKETENEINTERMEDIATE AND THEIR USE FOR THE STEREOSELECTIVE SYNTHESIS OF AMINO-ACIDS

Reaction of 5-isonitroso-2,2-dimethyl-1,3-dioxane-4,6-dione with vario us ketones under reflux in toluene gives 3-oxazolin-5-one 3-oxides (cy clic nitrones) via a nitrosoketene intermediate generated from the iso nitroso derivative. The cyclic nitrones can be used for the stereosele ctive [3 + 2] dipolar cycloaddition to electron-rich olefins under hig h pressure to produce fused isoxazolidines. These isoxazolidines, in t urn, are versatile intermediates for the stereoselective preparation o f substituted alpha-amino acids.