Site-selective and regioselective cycloaddition of N-propadienylanilines with nitrile oxides. Claisen-type rearrangement of the cycloadducts

Abstract

The reaction of N-propadienylanilines with 3,5-dichloro-2,4,6-trimethylbenzonitrile oxide proceeds in a site-selective and regioselective fashion to give 5-substituted 4-methylene-4,5-dihydroisoxazoles. The latter compounds (i) add a second molecule of nitrile oxide to afford 4,5′-spirobi-(4,5-dihydroisoxazoles) and (ii) isomerise to 4-(2-aminobenzyl)isoxazoles through a Claisen-type rearrangement.