摘要：

It is well known that the photolysis of aryldisilanes gave the silenes containing Si=C bond as reaction intermediates since the earliest report on the photolysis of phenyl-pentamethyldisilane and (p-tolyl)pentamethyldisilane by Ishikawa et al. in 1975. The silenes arising from the 1,3-trimethylsilyl radical shift of a terminal silyl group in the disilane moiety onto an ortho carbon atom in the aryl ring upon irradiation react with various substrates to give the various photoproducts. In connection with the reactions of silene intermediates in the absence of trapping agents, Ishikawa and co-workers reported that the photolysis of 1,4-bis(pentamethyldisilanyl)benzene in hexane gave two isomeric dimers, 7,7,8,8-tetramethyl-3,12-bis(pentamethyl-disnanyl)-13,14-bis(trimethylsilyl)-7,8-disilatricyclo[7.3.1.1]-tetradeca-3,5,9,11-tetraene and 7,7,8,8-tetramethyl-3,12-bis(pentamethyldisilanyl)-10,14-bis(trimethylsilyl)-7,8-di-silatricyclo[7.3.1.1]tetradeca-3,5,9(13),11-tetraene, in a ratio of 1:1 through head-to-head dimerization of silene intermediate. Very recently, I reported that the photoreaction of (2-hydroxymethylphenyl)pentamethyldisilane in methanol provides a novel intramolecular photoproduct via silene intermediate arising from 1,3-migration of trimethylsilyl radical, which is formed via homolytic cleavage of siliconsilicon crbond in the disilane moiety upon irradiation to the C_6 position of benzene ring. In connection with my continuous studies for the utility of silacyclopropenes,1-silaallenes, and silenes as reaction intermediates in organic synthesis of silicon-containing heterocyclic compounds, the present author has now investigated the photochemistry of 4,4-bis(pentamethyldisilanyl)biphenyl 1 expecting the formation of two silene intermediates in one molecule. In this paper, I would like to report the detailed photochemical study of 4,4-bis(pentamethyldisilanyl)biphenyl.

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