Comparative chemistry of η3-oxaallyl and η3-allyl rhodium(I) complexes in the hydrosilylation of cyclopropyl ketones: observation of an unprecedented rearrangement
作者:Carrie Sun、Ambrose Tu、Greg A. Slough
DOI:10.1016/s0022-328x(99)00041-8
日期:1999.6
Addition of η3-oxaallyl bis(triphenylphosphine)rhodium(I) (1) or η3-allyl bis(triphenylphosphine)rhodium(I) (2) to a mixture of cyclopropyl phenyl ketone and triethylsilane promotes two competitive catalytic reactions. Complex 1 gives high yields of the silyl ether 13, while complex 2 favors an unprecedented cyclopropyl carbinyl ring-opening reaction providing good yields of enol silane (Z)- and (E)-14
的加成η 3 -oxaallyl双(三苯基膦)铑(I)(1)或η 3 -烯丙基双(三苯基膦)铑(I)(2),以环丙基苯基酮和三乙基硅烷的混合物促进了两个相互竞争的催化反应。配合物1产生高产率的甲硅烷基醚13,而配合物2促进空前的环丙基羰基开环反应,提供良好的烯醇硅烷(Z)-和(E)-14(4.1 Z / E比率)。催化剂周转率的研究提供了证据,证明两种单体铑配合物是竞争反应的原因。环丙基羰基催化反应在狭窄的反应条件下进行,反应条件是使用一组适合该反应的特定酮底物。诸如三乙基硅烷之类的化学物质可激活催化作用,从而导致13,而三苯基膦则强烈抑制14的形成。提出了一种涉及极性过渡态的环丙基羰基重排的机理。
Controlled Hydrosilylation of Carbonyls and Imines Catalyzed by a Cationic Aluminum Alkyl Complex
作者:Jürgen Koller、Robert G. Bergman
DOI:10.1021/om2008277
日期:2012.4.9
The synthesis, characterization, and unprecedented catalytic activity of cationic aluminum alkyl complexes toward hydrosilylation are described. X-ray crystallographic analysis of Tp*AlMe2 (1) and [Tp*AlMe][I-3] (3) revealed the preference of Al for a tetrahedral coordination environment and the versatility of the Tp* ligand in stabilizing Al in bi- and tridentate coordination modes. [Tp*AlMe][MeB(C6F5)(3)] (2) is highly active toward the hydrosilylation of a wide variety of carbonyls and imines, thus providing an inexpensive and versatile alternative to late transition metal catalysts.
selected cyclopropanes as model substrates since they present a relatively weak σ-bond. Herein, we describe an iridium-catalyzed hydroboration of cyclopropanes, resulting in β-methyl alkylboronates. These unusually branched boronates can be derivatized by oxidation or cross-coupling chemistry, accessing "designer" products that are desired by practitioners of natural product synthesis and medicinal chemistry