Photochemically generated silicon-carbon double-bonded intermediates. 13. The formation and reactions of 1,2-disilacyclobutanes

Article abstract of DOI:10.1021/ja00399a031

The photolysis of 1-(trimethylsilylethynyl)-1,1-diphenyl-2,2,2-trimethyldisilane in the absence of a trapping agent afforded 1,1,2,2-tetraphenyl-3,4-bis[bis(trimethylsilyl)methylene]-1,2-disilacyclobutane (6). This compound could be transformed photochemically or thermally into 1,1,2,24etraphenyl-3-[bis(trimethylsilyl)ethenylidene]-4,4-bis(trimethylsilyl)- 1,2-disilacyclobutane (8). 1,2-Disilacyclobutanes 6 and 8 reacted with m-chloroperoxybenzoic acid to give the corresponding 1-oxa-2,5-disilacyclopentane derivatives. Thermolysis of 8 gave 1,1,3,3-tetraphenyl-2-[bis(trimethylsilyl)ethenylidene]-4,4-bis(trimethylsilyl)- 1,3-disilacyclobutane (10) and 1,1-dimethyl-2-[bis(trimethylsilyl)ethenylidene]-3,3-diphenyl-4,4- bis(phenyldimethylsilyl)-1,3-disilacyclobutane (11) in a ratio of 1:1. Thermolysis of 8 in the presence of anthracene afforded a 1:1 adduct of anthracene and 1,1-diphenyl-4,4-bis(trimethylsilyl)-1-silabutatriene in addition to 1,3-disilacyclobutane 10. When 8 was thermolyzed in the presence of a small excess of methanol, both 1,1-diphenyl-4,4-bis(trimethylsilyl)-1-silabutatriene and 1,1-diphenyl-2,2-bis-(trimethylsilyl)-1-silaethene were trapped by methanol. On heating 8 with elemental sulfur, a 1-thia-2,5-disilacyclopentane was produced. Preliminary results of an X-ray diffraction study of 11 are also described.