163223-90-3Relevant articles and documents
Zirconocene-mediated intramolecular carbon-carbon bond formation of two alkynyl groups of bis(alkynyl)silanes
Xi, Zhenfeng,Fischer, Reinald,Hara, Ryuichiro,Sun, Wen-Hua,Obora, Yasushi,Suzuki, Noriyuki,Nakajima, Kiyohiko,Takahashi, Tamotsu
, p. 12842 - 12848 (2007/10/03)
Treatment of bis(phenylethynyl)silane (PhC≡C)2SiR2 (R = Me (2a), Et (2b) or Ph (2c)) with Cp2ZrEt2 (1) (Cp = cyclopentadienyl) and H2O/CuCl in this order afforded (1E,3E)-1,4-diphenyl-1,3-butadiene (3) in 56-88% yields after hydrolysis. On the other hand, hydrolysis of the reaction mixture of 2a-h with Cp2ZrEt2 gave silacyclobutene derivatives 4a-h in 61-87% yields. Zirconium-containing intermediate 7 was obtained as crystals suitable for X- ray analysis when t-BuC5H4 was used as the ligands of a zirconocene derivative. Structure of 7 showed that the intermediate contained the zirconacyclobutene-silacyclobutene fused ring system. Reaction of silacyclobutene 4a with CuCl selectively opened the silacyclobutene ring. The further treatment of the reaction mixture with Phi in the presence of a catalytic amount of Pd(PPh3)4 gave 1,3,4-triphenyl-1-silyl-1,3-butadiene compound 16. Zirconacyclopentadienes with an alkynylsilyl group at the α- position afforded zirconacyclohexadiene derivatives 19 in 82-98% yields. When t-BuC5H4 was used as the ligands instead of two Cp, the structure was determined by X-ray analysis. The structure clearly showed that 19 had the zirconacyclohexadiene-silacyclobutene fused ring system.
