Kazuki Kojima

Isolation, structure and reaction of selenobenzophenones. X-Ray molecular structure of 4,4′-dimethoxyselenobenzophenone and of 4,4-biphenyl-2,3-diselenabicyclo[3.3.0]oct-7-ene

4,4′-Dimethoxy-1a and 4,4′-dimethyl-selenobenzophenone 1b could be isolated in moderate yields by the reaction of the corresponding ylides 3 with elemental selenium in benzene at 80 °C. Their spectral data are described. Attempted isolation of unsubstituted selenobenzophenone afforded only its dimer 5. Compound 1a crystallizes in space group P21/n with unit-cell parameters a= 7.191(3), b= 7.505(4), c= 24.856(4)A, β= 90.32(1)°, Z= 4, R= 0.055. The oxidation and thiation of 4,4′-dimethoxyselenobenzophenone 1a afforded the corresponding benzophenone and thiobenzophenone in good yields. The reaction of compound 1 with cyclopentadiene afforded the corresponding cycloadducts 7(3,3-diaryl-2-selenabicyclo[2.2.1] hept-5-enes), whereas bicyclic diselenides 8(4,4-diaryl-2, 3-diselenabicyclo[3.3.0]oct-7-enes) were obtained by using an excess of selenium and a higher temperature. Oxidation of compound 8c gave the corresponding diol 12, aldehyde 13, and diphenylfulvene 11. The reaction of compound 1a with benzenediazonium carboxylate afforded 2,2- bis-(4-methoxyphenyl)-4H-3,1 -benzooxaselenin -4-one 17.

Reactions of selenobenzophenones with dimethyl acetylenedicarboxylate or norbornadiene

Abstract Reactions of selenobenzophenones with dimethyl acetylenedicarboxylate or norbornadiene gave benzoselenapyranes or seven-membered cyclic selenides; these reactions might proceed through unusual type of cycloaddition reaction.

SELENOBENZOPHENONES AND DIAZOALKANES: REACTION AND MECHANISTIC ELUCIDATION

Abstract The reaction of selenobenzophenones with diazomethane afforded the corresponding diarylethylenes and symmetrical olefins. The reaction with other diazoalkanes gave three different types of olefins. This reaction proceeded through selenadiazoline intermediates and retrocyclization was observed.

A novel reaction of selenobenzophenones with tetracyanoethylene. Formation of a 2,3-dihydroselenophene

Abstract The reaction of selenobenzophenones with tetracyanoethylene (TCNE) exclusively affords an unusual type of adduct with the structure of 2,3-dihydroselenophene, sharply different from the reaction between thiobenzophenone and TCNE

Reactions of Selenobenzophenones with Olefins

Reactions of selenobenzophenones with methyl propiolate afforded two types of cycloadducts regioselectively. The reaction with tetracyanoethylene gave selenophene derivatives. Mechanisms of these reactions were discussed.