Thermal and electron transfer induced reactions of enediynes and enyne allenes .3. Intramolecular formal Diels-Alder reaction in enyne allenes. A new synthetic route to benzofluorenes and indeno[1,2-g]quinolines

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.