The configuration at the 2-position of 2-(p-bromophenyl)-N-methyl-4-phenyl-1, 3-oxazolidine (2a) was determined by X-ray analysis. The reactions of 2, 4-diphenyl- and 2-methyl-4-phenyl-1, 3-oxazolidines (2b-d and 2e-g) with methyl and phenylmagnesium bromides were investigated.