Stereocontrolled ring enlargement by diastereoselective Stevens rearrangement in chiral 1,3-oxazolidinium salts. A novel entry to enantiopure morpholines

摘要

Chiral oxazolidinium salts were prepared by treatment of (-)-ephedrine derived oxazolidines with allylic bromides. These quaternary salts undergo regio- and diastereoselective Stevens rearrangement by treatment with sodium hydride. The reaction constitutes a novel entry to enantiopure tetrasubstituted morpholines. [References: 28]