Intramolecular formal Diels-Alder reaction in enyne allenes. A new synthetic route to benzofluorenes and indeno[1,2- g]quinolines

Abstract

Through the use of aryl substituents at the acetylene terminus in enyne allenes the reaction mode may be changed from the Myers-Saito cyclization to a C 2C 6 cyclization resulting in a net intramolecular Diels-Alder reaction. As a consequence, the thermal cyclization of readily accessible acyclic enyne allenes allows for the synthesis of complex benzofluorene and 10H-indeno[1,2- g]quinoline derivatives.