Bis(imino)pyridine Cobalt-Catalyzed Dehydrogenative Silylation of Alkenes: Scope, Mechanism, and Origins of Selective Allylsilane Formation

详细信息    查看全文

• 作者：Crisita Carmen Hojilla Atienza ; Tianning Diao ; Keith J. Weller ; Susan A. Nye ; Kenrick M. Lewis ; Johannes G. P. Delis ; Julie L. Boyer ; Aroop K. Roy ; Paul J. Chirik
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：August 27, 2014
• 年：2014
• 卷：136
• 期：34
• 页码：12108-12118
• 全文大小：630K
• ISSN：1520-5126

文摘

The aryl-substituted bis(imino)pyridine cobalt methyl complex, (^MesPDI)CoCH₃ (^MesPDI = 2,6-(2,4,6-Me₃C₆H₂-N鈺怌Me)₂C₅H₃N), promotes the catalytic dehydrogenative silylation of linear 伪-olefins to selectively form the corresponding allylsilanes with commercially relevant tertiary silanes such as (Me₃SiO)₂MeSiH and (EtO)₃SiH. Dehydrogenative silylation of internal olefins such as cis- and trans-4-octene also exclusively produces the allylsilane with the silicon located at the terminus of the hydrocarbon chain, resulting in a highly selective base-metal-catalyzed method for the remote functionalization of C鈥揌 bonds with retention of unsaturation. The cobalt-catalyzed reactions also enable inexpensive 伪-olefins to serve as functional equivalents of the more valuable 伪, 蠅-dienes and offer a unique method for the cross-linking of silicone fluids with well-defined carbon spacers. Stoichiometric experiments and deuterium labeling studies support activation of the cobalt alkyl precursor to form a putative cobalt silyl, which undergoes 2,1-insertion of the alkene followed by selective 尾-hydrogen elimination from the carbon distal from the large tertiary silyl group and accounts for the observed selectivity for allylsilane formation.