Cyclopropane Intermediates from Insertion Reactions of Platinum-Carbenes: A Route to Heterospiranes

Abstract

Heteroaromatic-anchored enynals with a pendent alkene group were successfully cyclized through a Huisgen-type [3+2] cycloaddition to give a tetracyclic Pt-carbene complex that underwent insertion into the C-H bond in the beta-position to give fused cyclopropanes that are otherwise inaccessible. On heating, the cyclopropanes smoothly rearranged to form the corresponding heterospiranes with excellent levels of stereoselectivity and high yields.