A versatile and efficient method for the synthesis of benz[a]azulenic enones starting from readily available o-(2-furyl)cycloheptatrienylbenzenes

Abstract

A facile, one-pot synthesis of β-(benz[a]azulen-10-yl)-α,β-unsaturated ketones from the corresponding o-(2-furyl)cycloheptatrienylbenzenes is reported. A mechanism involving a novel ring-opening cyclisation reaction by the intramolecular attack of the tropylium ion to the 2-position of the furan ring is proposed.