Selective Intermolecular Coupling of Alkynes with Nitriles and Ketones via beta,beta' Carbon-Carbon Bond Cleavage of Zirconacyclopentenes.
Selective intermolecular coupling of alkynes with nitriles and ketones was performed by the reaction of a mixture of alkynes and Cp(2)ZrEt(2) with nitriles and ketones, respectively. Hydrolysis of the mixture gave alpha,beta-unsaturated ketones and allylic alcohols in good to excellent yields, respectively. These reactions proceeded via zirconacyclopentenes which were prepared by the reaction of alkynes with Cp(2)ZrEt(2). The structure of zirconacyclopentene, which was prepared from diphenylacetylene and Cp(2)ZrEt(2), was determined by X-ray analysis. It clearly indicated that there is a single bond between the beta- and beta'-carbons of the zirconacyclopentene. The reaction of zirconacyclopentenes with nitriles or ketones proceeded via the beta,beta' carbon-carbon bond cleavage of the zirconacyclopentenes. In a similar way, addition of PMe(3) to the zirconacyclopentene afforded a zirconocene-alkyne complex in 87% yield.
Takahashi
Tamotsu
T
Catalysis Research Center and Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060, Japan, Aichi University of Education, Igaya, Kariya, Aichi 444, Japan, and Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.
Xi
Chanjuan
C
Xi
Zhenfeng
Z
Kageyama
Motohiro
M
Fischer
Reinald
R
Nakajima
Kiyohiko
K
Negishi Ei
Ei-ichi