Cobalt-Catalyzed Regiodivergent Hydrosilylation of Vinylarenes and Aliphatic Alkenes: Ligand- and Silane-Dependent Regioselectivities
作者:Chao Wang、Wei Jie Teo、Shaozhong Ge
DOI:10.1021/acscatal.6b02518
日期:2017.1.6
hydrosilylation of alkenes catalyzed by catalysts generated in situ from bench-stable Co(acac)2 and phosphine- or nitrogen-based ligands. A wide range of vinylarenes and aliphatic alkenes reacted to afford either branched (45 examples) or linear (37 examples) organosilanes in high isolated yields (average: 84%) and high regioselectivities (from 91:9 to >99:1). This transformation tolerates a variety of functional
solvent-free cobalt-catalyzed highly selective hydrosilylation of alkenes has been developed. It was found that both Co(PMe3)4 and CoCl(PMe3)3 are highly active catalysts for hydrosilylation of alkenes. The former promoted Markovnikov-type hydrosilylation of the aryl alkenes, while the latter catalyzed anti-Markovnikov-type hydrosilylation of the alkyl alkenes. These two catalytic systems tolerate a variety
unsymmetrical N-heterocyclic carbene (NHC) [CNC]-pincer preligands with CoMe(PMe3)4 gave rise to NHC [CNC]-pincer cobalt(III) hydrides, [(CcarbeneNaminoCnaphthyl)Co(H)(PMe3)2] (3a) and (3b), via Csp2–H activation and the unexpected trans-bischelate [Ccarbene, Namino] cobalt(II) complexes 4a and 4b via a disproportionation reaction, respectively. It was found that both 3a and 3b are efficient catalysts
CoCl(PMe3)3 to give [P,C]-chelate cobalt(III) hydrides [mer-(Me3P)3Co(H)(Cl)(o-Ph2P–C6H4–C═O)] (1) or [mer-(Me3P)3Co(H)(Cl)(o-iPr2P–C6H4–C═O)] (2), respectively. Complex 2 was new and characterized by spectroscopic methods and single-crystal X-ray diffraction analysis. It was found that both complex 1 and 2 are active catalysts for hydrosilylation of alkenes. Although the catalyticactivity of 1 is slightly
双齿配体 2-二苯基膦基苯甲醛或 2-二异丙基膦基苯甲醛与 CoCl(PMe 3 ) 3反应得到 [P,C]-螯合钴 (III) 氢化物 [ mer -(Me 3 P) 3 Co(H)(Cl)( o - Ph 2 P–C 6 H 4 –C=O)] ( 1 ) 或 [ mer -(Me 3 P) 3 Co(H)(Cl)( o - i Pr 2 P–C 6 H 4 –C=O )] ( 2 ) 分别。复合体2是新的,并通过光谱方法和单晶 X 射线衍射分析进行表征。发现配合物1和2都是烯烃氢化硅烷化的活性催化剂。虽然催化活性1略高,催化剂1和2具有相同的选择性。芳香族烯烃的选择性主要是马尔可夫尼科夫型,而脂肪族烯烃的选择性几乎是 100% 的反马尔可夫尼科夫型。在反应机理研究中,从氢化物1的化学计量反应中分离出甲硅烷基二氢化钴[(Ph 2 ClSi)Co(H) 2 (PMe 3 ) 3 ]与Ph 2
Iron-Catalyzed <i>E</i>-Selective Dehydrogenative Borylation of Vinylarenes with Pinacolborane
作者:Chao Wang、Caizhi Wu、Shaozhong Ge
DOI:10.1021/acscatal.6b02654
日期:2016.11.4
borylation of vinylarenes with pinacolborane (HBpin) catalyzed by an iron(0) complex “(PMe3)4Fe”. A variety of monosubstituted and disubstituted vinylarenes underwent this iron-catalyzed transformation, affording E-vinyl boronate esters (VBEs) selectively in high yields. In addition, we coupled this iron-catalyzed dehydrogenative borylation with further transformations of the resulting vinyl boronate esters