ISOXAZOLIDIN-5-ONE ISOXAZOLIDINE REARRANGEMENT, AN ENTRY TO 3-AMINO-3-DEOXY SUGARS

Conjugate addition - rearrangement of N-benzylhydroxylamine to alpha , beta-unsaturated lactones 1 provides a short and effective route to 3- substituted isoxazolidin-5-ones. High and defined stereochemistry of t his reaction with simultaneous liberation of the 5-OH group of the sug ar chain, while all other groups remain protected, creates a possibili ty to switch from sugars of the D-configurational series to those of t he L-series, thus providing a very attractive entry to important 3-ami no-2,3-dideoxy sugars. Mesylation of the 2'-OH group of the isoxazolid in-5-one skeleton or introduction of an epoxide ring to C-2',3' carbon atoms and subsequent treatment of the molecule with a nucleophile cau ses isoxazolidin-5-one - isoxazolidine rearrangement with inversion of the configuration at the C-2 carbon atom.