1,3-Dipolar Cycloaddition of Chirally Modified Vinylboronic Ester with Nitrile Oxides

Chiral modified vinylboronic ester 1, derived from d-(+)-mannitol, reacted with nitrile oxides to afford optically active isoxazolines. The regioselectivity was excellent and moderate stereoselectivity (up to 60% d.e.) was achieved. The configuration of new chiral centres in all the isoxazoline products was established by NMR analysis or X-ray analysis.