The reaction of allylic phosphates with the title organoaluminium reagent (PhMe2Si-AlEt2) provides allylsilanes in good yields. Cross coupling of enol phosphates with PhMe2Si-Mtl (Mtl = AlEt2 or MgMe) produces vinylsilanes regio- and stereoselectively in the presence of Pd(0) catalysts.
Cobalt-Catalyzed Regio- and Stereoselective Hydrosilylation of Alk-2-ynes with Tertiary Silanes
作者:Hongfang Li、Chengbo Yang、Dongyang Wang、Liang Deng
DOI:10.1021/acs.organomet.2c00563
日期:——
Selectivity control in the addition reactions of internal alkynes that bear two similar substituents presents a big challenge in modern organicsynthesis. Herein we report that β-(E)-selective hydrosilylation of alk-2-ynes with tertiary silanes can be achieved by using Co2(CO)8 as the catalyst. Under the catalytic reaction conditions, a wide range of alk-2-ynes can be converted into vinylsilanes with
带有两个相似取代基的内部炔烃加成反应的选择性控制对现代有机合成提出了巨大的挑战。在此我们报道了通过使用Co 2 (CO) 8作为催化剂可以实现烷-2-炔与叔硅烷的β-( E )-选择性氢化硅烷化。在催化反应条件下,多种烷-2-炔可以转化为乙烯基硅烷,其中β-( E )异构体作为主要或唯一的氢化硅烷化产物。机理研究表明炔桥二钴物质是可能的中间体。烯基桥联二钴甲硅烷基中间体中取代基之间的空间排斥被认为是引起观察到的区域选择性的关键因素。
Regioselectivity of the Singlet Oxygen Ene Reaction (Schenck Reaction) with Vinylsilanes
作者:Waldemar Adam、Markus J. Richter
DOI:10.1021/jo00091a020
日期:1994.6
The ene reaction-of singlet oxygen and vinylsilanes 1 with various substitution patterns and double-bond geometry has been studied. beta-Silyl allylic hydroperoxides 2 were the major products of the photooxygenation, accompanied by smaller amounts of alpha,beta-unsaturated ketones 3. The latter derive from decomposition of the regioisomeric alpha-hydroperoxy silanes 4 by elimination of silanol. Regioselectivities up to 97:3 were observed for vinylsilanes with a methyl group geminal to the silyl group and with cyclic derivatives. Z-Configurated substrates showed lower regioselectivity and reactivity. Elongation of the carbon chain at the geminal position also increased the amount enone formed. These results are rationalized in terms of stereoelectronic effects imposed by the silyl group on the ring-opening of the perepoxide intermediate.