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

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. A cascade synthetic strategy for the direct synthesis of dibenzo[ a , d ]cycloheptanoids and dibenz[ a , c ]anthracene-9,14-dione derivatives from aryne precursors has been developed.