Photochemical Dimerization of a Benzoselenete Derivative

Article abstract of DOI:10.1021/jo00262a050

A synthetic approach to a benzoselenete derivative is examined.Photolysis of 2-diazobenzoselenophen-3(2H)-one (7) in methanol gave mainly 2-methoxybenzoselenophen-3(2H)-one (11).Photolysis of 3-diazobenzoselenophen-2(3H)-one (8) in methanol gave dimethyl 1,5-diazodiselenocin-2,6-dicarboxylate (14) instead of methyl 2H-1-benzoselenete-2-carboxylate (9). 14 is generated presumably by dimerization of the benzoselenete derivative.A theoretical comparative study of the benzothiete and benzoselenete is made on their parent compounds.An STO-3G ab initio MO calculation reveals that the o-quinoid forms of both compounds are absent in the ground state.The dimerization is suggested to take place in the lowest (n,?^*) type excited state.