Catalytic, formal homo-Nazarov-type cyclizations of alkylidene cyclopropane-1,1-ketoesters: access to functionalized arenes and heteroaromatics.

A catalytic, formal homo-Nazarov-type cyclization of alkylidene cyclopropanes (ACPs) to give functionalized arenes and heteroaromatics is reported. In the presence of a Lewis acid catalyst, the ACP 1,1-ketoesters undergo distal bond cleavage to afford an allyl cation intermediate. Adjacent π-attack on the allyl cation then provides a six-membered ring that undergoes rapid aromatization.