779348-75-3Relevant academic research and scientific papers
Au- and Pt-catalyzed cycloisomerizations of 1,5-enynes to cyclohexadienes with a broad alkyne scope
Sun, Jianwei,Conley, Matthew P.,Zhang, Liming,Kozmin, Sergey A.
, p. 9705 - 9710 (2007/10/03)
We describe the development of gold- and platinum-catalyzed cycloisomerizations of 1,5-enynes. This catalytic process displays a wide alkyne scope and furnishes a range of highly functionalized 1,4- and 1,3-cyclohexadienes. In the case of 1-siloxy-1-yne-5-enes, the reactions are efficiently catalyzed by AuCl (1 mol %) at ambient temperature to afford siloxy cyclohexadienes or the corresponding 1,2- and 1,3-cyclohexenones upon subsequent protodesilylation. We propose that the reaction proceeds via a novel mechanism involving a series of 1,2-alkyl shifts. Elucidation of this unusual reaction mechanism enabled us, in turn, to significantly expand the scope of the cycloisomerization by incorporation of a quaternary center at the C(3) position of the enyne. Indeed, we established that PtCl2 (5 mol %) efficiently catalyzed the cycloisomerizations of 1,5-enynes containing terminal, internal, and arene-conjugated alkynes. Since a variety of 1,5-enynes are readily accessible, the cycloisomerization provides a rapid approach to a wide range of highy substituted cyclohexadienes for many subsequent synthetic applications.
Gold-catalyzed cycloisomerization of siloxy enynes to cyclohexadienes
Zhang, Liming,Kozmin, Sergey A.
, p. 11806 - 11807 (2007/10/03)
We have described the first Au-catalyzed cycloisomerization of 1-siloxy-5-en-1-ynes. The reaction is efficiently catalyzed by AuCl (1 mol %) to afford siloxy cyclohexadienes, which can be readily converted to the corresponding 1,2- and 1,3-cyclohexenones. The catalytic process displays a broad substrate scope and exceedingly mild reaction conditions (30 min, 20 °C). The presence of a siloxy alkyne moiety is crucial for enabling the skeletal reorganization process, which is postulated to proceed via a novel reaction mechanism involving a cascade of 1,2-alkyl migrations. Copyright
