Raya Balaram, Biswas Souvagya, RajanBabu T V
Department of Chemistry and Biochemistry, 100 W. 18th Avenue, The Ohio State University, Columbus, Ohio 43210 USA.
ACS Catal. 2016 Sep 2;6(9):6318-6323. doi: 10.1021/acscatal.6b02272. Epub 2016 Aug 12.
While attempting to effect Co-catalyzed hydrosilylation of β-vinyl trimethylsilyl enol ethers we discovered that depending on the silane, solvent and the method of generation of the reduced cobalt catalyst, a highly efficient and selective reduction or hydrosilylation of an alkene can be achieved. This paper deals with this reduction reaction, which has not been reported before in spite of the huge research activity in this area. The reaction, which uses an air-stable [2,6-di(aryliminoyl)pyridine)]CoCl activated by 2 equivalents of NaEtBH as a catalyst (0.001-0.05 equiv) and (EtO)SiMeH as the hydrogen source, is best run at ambient temperature in toluene and is highly selective for the reduction of simple unsubstituted 1-alkenes and the terminal double bonds in 1,3- and 1,4-dienes, β-vinyl ketones and silyloxy dienes. The reaction is tolerant of various functional groups such as a bromide, alcohol, amine, carbonyl, and di or trisubstituted double bonds, and water. Highly selective reduction of a terminal alkyne to either an alkene or alkane can be accomplished by using stoichiometric amounts of the silane. Preliminary mechanistic studies indicate that the reaction is stoichiometric in the silane and both hydrogens in the product come from the silane.
在尝试实现β-乙烯基三甲基硅基烯醇醚的共催化硅氢化反应时，我们发现，根据硅烷、溶剂以及还原钴催化剂的生成方法，可以实现烯烃的高效和选择性还原或硅氢化反应。本文论述了这一还原反应，尽管该领域已有大量研究活动，但此前尚未见相关报道。该反应使用由2当量的NaEtBH活化的空气稳定的[2,6-二（芳基亚氨基）吡啶]CoCl作为催化剂（0.001 - 0.05当量），并以(EtO)SiMeH作为氢源，最好在甲苯中于室温下进行，对简单的未取代1-烯烃以及1,3-和1,4-二烯中的末端双键、β-乙烯基酮和硅氧基二烯的还原具有高度选择性。该反应对各种官能团如溴化物、醇、胺、羰基以及二取代或三取代双键和水具有耐受性。通过使用化学计量的硅烷，可以实现末端炔烃向烯烃或烷烃的高度选择性还原。初步机理研究表明，该反应在硅烷中是化学计量的，产物中的两个氢均来自硅烷。
