Reaction of diene-conjugated 1,3-dipolar intermediates: the formation of cycloprop[c]isoquinolines from benzonitrile o-alkenylbenzyl ylides and their rearrangements to 2-benzazepines

Abstract

The α,β:γ,δ-unsaturated nitrile ylides (9), when generated by the 1,3-dehydrochlorination of the benzimidoyl chlorides (8) at room temperature, react by a stereospecific 1,1-cycloaddition to give the cyloprop[c]isoquinolines (10); the latter undergo two types of thermal rearrangement giving the 1H-2-benzazepines (14) when R¹ or R²= H, and the 5H-2-benzazepines (17) when R¹= Ph and R²= Ph or Me.