Synthesis of oxazolidines using DMSO/P4O10 as a formaldehyde equivalent

Compounds containing a substituted oxazolidine ring were prepared in excellent yields in two steps from cis or trans 3-phenylglycidate. When an electron donating amine was used in the nucleophilic opening of an epoxide, treatment of the resulting β-amino-α-hydroxy ester with DMSO/P4O10 led to the formation of cis or trans oxazolidines. This simple and practical procedure was readily adapted to the synthesis of enantiopure oxazolidines, using DMSO/P4O10 because of the availability of the enantiopure halohydrins from enzymatic reduction of the β-chloro-α-ketoester.