Metal-promoted cyclization. 19. Novel bicyclization of enynes and diynes promoted by zirconocene derivatives and conversion of zirconabicycles into bicyclic enones via carbonylation
作者:Eiichi Negishi、Steven J. Holmes、James M. Tour、Joseph A. Miller、Fredrik E. Cederbaum、Douglas R. Swanson、Tamotsu Takahashi
DOI:10.1021/ja00191a035
日期:1989.4
Novel zirconacyclopentadiene complex; 8,8-bis(cyclopentadienyl)-7,9-bis(trimethylstannyl)-8-zirconabicyclo-[4.3.0]nona-1(9),6(7)-diene: synthesis, X-ray analysis, and catalytic activity for ethylene polymerization
Zirconacyclopentadiene complex 2c containing gem-dimetallated carbon atoms by zirconium and tin was prepared by the oxidative coupling reaction of 'Cp(2)Zr' with distannyldiyne compounds. Complex 2c having trimethylstannyl groups was characterized by X-ray diffraction and its structure was compared with zirconacyclopentadiene analogues having tert-butyl groups (2a) or trimethylsilyl groups (3). The five-membered zirconacycle ring of 2c has a planar conformation whereas it is twisted in complexes 2a and 3. The C-Zr-C angle in 2c is smaller than those of the corresponding 2a and 3. The polymerization of ethylene proceeded when these complexes were used in combination with methylaluminoxane and it was found that the catalytic activities of these complexes were remarkably influenced by the substituents on the alpha-carbon atoms.
YOUSAF, SHAHID M.;FARONA, MICHAEL F.;SHIVELY, RAYMOND J. (JR);YOUNGS, WIL+, J. ORGANOMET. CHEM., 363,(1989) N, C. 281-289
作者:YOUSAF, SHAHID M.、FARONA, MICHAEL F.、SHIVELY, RAYMOND J. (JR)、YOUNGS, WIL+