CHIRAL VINYL PHOSPHINE OXIDES - DOUBLE ASYMMETRIC INDUCTION IN THE 1,3-DIPOLAR CYCLOADDITION TO CHIRAL NITRONES - KINETIC RESOLUTION OF A RACEMIC PHOSPHOLENE OXIDE

The 1,3-dipolar cycloaddition of nitrones with chiral vinylphosphine o xides or sulfides provides 5-phosphinyl substituted isoxazolidines wit h selectivity up to 99:1. Use of chiral nitrones allows a more general ized stereoselective synthesis of these compounds, also by means of a double asymmetric induction. With a racemic phospholene oxide, the hig h diastereofacial selectivity of the cycloaddition gives rise to a sin gle 4-phosphinyl substituted isoxazolidine from each enantiomer. Moreo ver, a certain degree of enantiomeric discrimination permits a partial kinetic resolution of the phospholene oxide.