A ternary catalytic system consisting of a cobalt salt, a diphosphine ligand, and a Grignard reagent promotes syn-addition of an azole C(2)-H bond across an unactivated internal alkyne with high chemo-, regio-, and stereoselectivities under mild conditions. Mechanistic experiments suggest that the reaction involves oxidative addition of the oxazolyl C-H bond to the cobalt center, alkyne insertion into the Co-H bond, and reductive elimination of the resulting diorganocobalt species.
system for an intermolecular addition of formamides to alkynes has been developed. The reaction of formamides with internal alkynes in the presence of a palladium catalyst with acid chloride as an additive afforded (E)-alpha,beta-unsaturated amides regio- and stereoselectively. The same catalyst system realized the first example of the addition of formamides to terminal alkynes giving the corresponding
Nickel(0)-Catalyzed Enantioselective Annulations of Alkynes and Arylenoates Enabled by a Chiral NHC Ligand: Efficient Access to Cyclopentenones
作者:Joachim S. E. Ahlin、Pavel A. Donets、Nicolai Cramer
DOI:10.1002/anie.201408364
日期:2014.11.24
nickel‐catalyzed reductive [3+2] cycloaddition of α,β‐unsaturated aromatic esters and alkynes constitutes an efficient method for their synthesis. Here, nickel(0) catalysts comprising a chiral bulky C1‐symmetric N‐heterocyclic carbene ligand were shown to enable an efficient asymmetric synthesis of cyclopentenones from mesityl enoates and internal alkynes under mild conditions. The bulky NHC ligand
A method for direct synthesis of tetrasubstituted fluoroarenesvia nickel‐catalyzed [2+2+2] cycloaddition is presented. The reaction combines one molecule of 1,1‐difluoroethylene with two molecules of alkynes and involves sequential cleavage of the CF and CH bonds in difluoroethylene. The catalytic cycle is established by reduction of the intermediary NiII fluoride with a triethylborane‐based borate
Simple and reactive Ir(<scp>i</scp>) N-heterocyclic carbene complexes for alkyne activation
作者:Mark R. D. Gatus、Indrek Pernik、Joshua A. Tompsett、Samantha C. Binding、Matthew B. Peterson、Barbara A. Messerle
DOI:10.1039/c9dt00313d
日期:——
Two simple unsymmetrical monometallic Ir(I) complexes with an N-heterocycliccarbeneligand and an analogous bimetallic Ir(I) complex were synthesised. These complexes were found to be extremely active catalysts for a range of C–X (X = N or O) and Si–N bond forming reactions involving alkyne and imine activation for dihydroalkoxylation, hydroamination and hydrosilylation reactions. These catalysts
Gold(III) NHC Complexes for Catalyzing Dihydroalkoxylation and Hydroamination Reactions
作者:Ashwin G. Nair、Roy T. McBurney、Mark R. D. Gatus、Samantha C. Binding、Barbara A. Messerle
DOI:10.1021/acs.inorgchem.7b02161
日期:2017.10.2
Furthermore, [LAu(III)Cl3] catalyzed intra- and intermolecular hydroamination reactions, achieving good to excellent conversions. [LAu(III)Cl3] is a more efficient catalyst than a gold(I) analogue, [LAu(I)Cl]. The dependence of the quantity of weakly coordinating anion [BArF4]− ((3,5-trifluoromethyl)phenyl borate) present on catalysis efficiency was probed for the dihydroalkoxylation reaction. X-ray diffraction
N-杂环卡宾基半不稳定配体与两个侧重吡唑臂(1,3-双((1 H-吡唑-3-基)甲基)-2,3-二氢-1 H-咪唑的金(III)络合物,LH)被合成。络合物[ L Au(III)Cl 3 ]是在室温下甚至在0℃下催化该反应的促进二氢烷氧基化的极好的催化剂。[ L Au(III)Cl 3 ]是迄今为止报道的炔二醇螺环化最有效的催化剂之一。此外,[ L Au(III)Cl 3 ]催化了分子内和分子间加氢胺化反应,实现了良好的转化率。[ L Au(III)Cl3 ]是一种比金(I)类似物[ L Au(I)Cl]更有效的催化剂。对于二氢烷氧基化反应,探查了存在的弱配位阴离子[BAr F 4 ] -((3,5-三氟甲基)苯基硼酸酯)的量对催化效率的依赖性。单晶的X射线衍射分析表明,金配合物[ L Au(III)Cl 3 ]和[ L Au(I)Cl]的固态结构分别显示了预期的正方形平面和线性配位几何形状。