Shuzo Yamada

Photochemical reactions of phenylacetylenes with ethylene trithiocarbonate. Synthesis of phenyl-substituted 2-thioxo-1,3-dithioles

A novel photochemical synthetic route to phenyl-substituted 2-thioxo-1,3-dithioles (TDT), intermediates in the synthesis of tetrathiafulvalenes (TTF), starting from ethylene trithiocarbonate (ETC) and phenylacetylenes is described. Phenyl- and diphenyl-acetylene and 1-phenylpropyne reacted with ETC derivatives in reasonable yields. The fluorescence of the acetylenes was quenched by ETC via a trivial process: sensitization with benzophenone and quenching with air suggested that the reaction proceeded mainly through the triplet excited states of the acetylenes. Irradiation of ETC alone with light of longer wavelength and quenching experiments suggested that the excited singlet state of ETC also participated in the reaction, in a minor process.

Fragmentation of laudanosine by single electron transfer reactions

The radical cation of laudanosine, formed by a photoinduced electron transfer reaction or by oxidation with a tris(4-bromophenyl)aminium salt, undergoes cleavage of a C–C bond similar to the mass spectrometric fragmentation induced by electron ionization.

Photoinduced electron-transfer reactions of 1,3,5-tricyanobenzene with olefins

Photoinduced electron-transfer of 1,3,5-tricyanobenzene (1) with 2,3-dimethylbut-2-ene leads to a novel annelation to give an indane derivative, while that with 2-methylbut-2-ene or tetrachloroethylene results in substitution at C-1 or C-2 of (1), respectively.

Photoinduced substitution of 1,3,5-tricyanobenzene by toluene

Irradiation of a solution of 1,3,5-tricyanobenzene in acetonitrile in the presence of toluene gives 1-benzyl-3,5-dicyanobenzene and 1-benzyl-3,5,6-tricyanobenzene. In a toluene solution only bibenzyl is obtained. On the basis of results obtained using [2H8]toluene (i.e. deuterium incorporation only in the benzyl and not in the cyanoaromatic moiety) a series of reactions which involves photoinduced electron-transfer, removal of proton from the radical cation, and then coupling of the radical anion and the radical formed is postulated. It is also suggested that for the coupling reaction to take place then the reduction potential for radical anion to dianion on the cyanoaromatic species might play an important role.

Photochemical reactions of N-alkyl-and N-aryl-1,4-iminonaphthalene derivatives

Upon irradiation N-alkyl- andN-aryl-1,4-dihydro-1,4-iminonaphthalene derivatives undergo photoisomerization to give mainly azatricycloundecatetraene and/or naphthalene derivatives depending upon the substituents on the nitrogen atom and the aromatic ring.