AN ANNULATION METHOD FOR THE SYNTHESIS OF HIGHLY SUBSTITUTED POLYCYCLIC AROMATIC AND HETEROAROMATIC-COMPOUNDS

A general strategy for the synthesis of highly substituted polycyclic aromatic and heteroaromatic compounds has been developed. The new aromatic annulation is achieved simply by the irradiation of a dichloroethane solution of an acetylene derivative and a vinyl or aryl-diazo ketone. Mechanistically, the reaction proceeds via the photochemical Wolff rearrangement of the diazo ketone to generate an aryl- or vinylketene, followed by a cascade of three pericyclic reactions. A variety of substituted phenols, naphthalenes, benzofurans, benzothiophenes, indoles, and carbazoles can be prepared by using the method. The application of the aromatic annulation to the total synthesis of the marine alkaloid hyellazole demonstrates the synthetic utility of the method. © 1990, American Chemical Society. All rights reserved.