Photochemical reaction between acenaphthene and arenecarbonitriles

Abstract

Various aromatic nitriles have been irradiated in acetonitrile in the presence of acenaphthene. The observed reactions involve electron-transfer quenching of the singlet excited state of the nitriles, and lead to replacement of a cyano group with an acenaphthenyl when starting from 1,4-dicyanobenzene and 1,2,4,5-tetracyanobenzene [here, also irradiating the ground-state electron-donor–acceptor (EDA) complex]. With 9,10-dicyanoanthracene (DCA) only biacenaphthenyls and reduced DCA are formed. With 1,4-dicyanonaphthalene the reaction is more complex, and both substitution of a cyano group and addition to yield 1- or 2-(acenaphthen-1-yl)-1,2-dihydro derivatives are obtained; furthermore, a product resulting from both reaction at the benzylic position and cycloaddition onto the 2a,3 bond of acenaphthene is isolated, and shown to be formed independently from the above adducts.