Regio- and stereoselectivity of the formation of 1,3-oxazolidines in the reaction of l-ephedrine with phenylglyoxal. Unexpected rearrangement of 2-benzoyl-3,4-dimethyl-5-phenyl-1,3-oxazolidine to 4,5-dimethyl-3,6-diphenylmorpholin-2-one.
Optically active 2-benzoyl-3,4-dimethyl-5-phenyl-1,3-oxazolidines, obtained by the reaction of l-ephedrine with phenylglyoxal, after keeping without solvent undergo a spontaneous stereospecific rearrangement to 4,5-dimethyl-3,6-diphenylmorpholin-2-one.