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The photochemical precursors, 1,1,1,3,3,3-hexamethyl-2-phenyltrisilane(2) and 2,3-dicarbomethoxy-1,4,5,6,7-pentaphenyl-7-silanorbornadiene(5) were synthesized in the yield of 10% and 73%, respectively. Irradiation of 2 at 254 nm in the presence of triethylsilane gave 1,1,1-triethyl-2-phenyldisilane (6) in 44% yield which was the product of phenylsilylene insertion into the Si-H bond. Irradiation of 2 in the presence of diphenylacetylene gave 1-phenyl-1-silacyclopenta-2,4-diene(4) in 68% yield together with 1,2-diphenyl-1,2-disilacyclohexa-2,5-diene(26%) which were formed from [2＋2] addition of the silacyclopropene to diphenylacethylene and formed from dimerization of silacyclopropene, respectively. From the neat photolysis of precursor 2,1,5-dihydrosilanthrene(11), intermolecular C-H insertion product of phenylsilylene and 1,2-diphenyltrisilane(12), Si-H insertion product of phenylsilylene to the precursor were obtained in the yield of 5% and 7%, respectively. In the same experimental condition, both photolyses of 5 in the presence of triethylsilane and methanol showed that the intramolecular 1,5-sigmatropic rearrangement of precursor 5 to give the formation of silylenolether was more favorable process than the generation of phenylsilylene.
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