(5R)-7,8:9,10-Di-O-isopropylidene-2,6-dioxa-4-azaspiro(4,5)decan-3-one: A New Chiral Spirooxazolidin-2-one Derived from D-(+)-Galactose for Use in Asymmetric Transformations.

Starting from D-(+)-galactose, the crystalline spirooxazolidin-2-one 2 can be readily prepared in an optically pure state by a nitrene-mediated four-step sequence, and serves to control both aldol and Diels–Alder reactions with high chiral efficiency, being easy to remove after use.