Photochemical reaction of arenecarbonitriles in the presence of alkylsilanes, silyl ethers and silyl amines

Abstract

The irradiation of benzene-1, 2, 4, 5-tetracarbonitrile, and benzene-1, 2, 4- as well as benzene-1, 3, 5-tricarbonitrile in the presence of various tetraalkylsilanes, alkoxytrialkylsilanes, hexamethyldisiloxane or heptamethyldisilazane leads to alkylation of the aromatics. The more substituted alkyl group is selectively fragmented, and the attack takes place at the position(s) of highest spin density in the nitrile radical anion. The reaction involves electron transfer to the nitrile's singlet excited state, and the radical cation appears to cleave mainly in the initial radical ion pair.