I. Addition of arylhalocarbenes to vinyl isocyanates II. Synthesis of highly functionalized dihydro- and tetrahydrofuran derivates via [3+2] cycloaddition III. Synthesis of benzoxepines

A series of arylhalocarbenes reactions with vinyl isocyanate has been presented. Most of these carbenes underwent a [2+1] cycloaddition to the vinyl isocyanate, but one of the more electron rich carbenes afforded a mixture of [2+1] and the [4+1] cycloadducts.; A novel [3+2] cycloaddition was performed using oxadiazolines to generate the 1,3-dipolar intermediates. This carbonyl ylides was successfully reacted with a variety of electron deficient alkenes and alkynes to obtain highly functionalized dihydro- and tetrahydrofuran derivatives.; Some of the dihydrofuran derivatives were treated with borontribromide to deprotect the aryl methyl ether and this lead to a novel rearrangement to the benzoxepine. This methodology was employed dihydrofaran derivatives with a variety of aryl rings and resulted in the functionalized benzoxepines.