STEREOCHEMISTRY-60 KINETIC CONTROL OF ASYMMETRIC INDUCTION DURING OXAZOLIDINE FORMATION FROM (-)-EPHEDRINE AND AROMATIC ALDEHYDES

Article abstract of DOI:10.1016/S0040-4020(01)96496-8

Kinetically controlled oxazolidine formation was observed with aromatic aldehydes substituted by electron-withdrawing groups.The stereoselectivity is solvent dependent: non-stereoselective ring closure occurred in chloroform while a high diastereodifferentiation was observed in methanol.The first oxazolidine showing an unambiguous 2R configuration was synthesized from p-bromobenzaldehyde and (-)-ephedrine in alcohol medium.A mechanism involving a nucleophilic assistance by alcoholic solvents is suggested in order to clarify the differences in stereoselectivity.