Photochemical reaction of phthalimides and dicyanophthalimides with benzylic donors

Irradn. of phthalimides I in the presence of benzylic donors PhCR1HX (R1 = H, Ph; X = H, SiMe3, CHPh2) proceeds via electron transfer and radical cation cleavage, resulting in benzylation at the carboximide moiety to yield 3-benzyl-3-hydroxyisoindol-1-ones. With 4,5-dicyanophthalimide and its N-Me deriv., substitution of benzyl for a cyano group is a competitive, and in some cases predominating, pathway. A rationalization is proposed on the basis of the in cage vs. out of cage radical cation cleavage.