Synthesis of dibenzo[a,d]cycloheptanoids via aryne insertion into 2-arylidene-1,3-indandiones

Abstract

A novel and unexpected aryne insertion cascade reaction on 2-arylidene-1,3-indandiones via conjugate addition of fluoride followed by formal C–C insertion is developed to afford dibenzo[a,d]cycloheptanoid derivatives in good yields with a single isomer. This reaction represents a rare instance of cyclic enone C–C bond insertion (acyl-alkenylation) in aryne chemistry. Interestingly, 2-arylidene-1,3-indandiones bearing electron rich functional groups provided dibenz[a,c]anthracene-9,14-dione derivatives via [4 + 2] cycloaddition followed by ring expansion.