The photoreactions of diphenylhomobenzoquinones la-d bearing 2-bromo and 2-methyl substituents have been investigated in the presence of amine donors. The products of these reactions are much dependent on the substituents and the nature of added amines. Irradiation of 1-bromo substituted diphenylhomobenzoquinone 1a with triethylamine (TEA) resulted in ring-opening of the fused-cyclopropane moiety to