Chelation-controlled, palladium-catalyzed arylation of enol ethers with aryl triflates. Ligand control of selection for α-or β-arylation of [2-(dimethylamino)ethoxy]ethene.
Palladium-catalyzed arylation reactions of [2-(Dimethylamino)ethoxy]ethene (1) with a series of aryl triflates were performed under a variety of reaction conditions. In particular, the influence of phosphine ligands and halide additives on regioselectivity were studied. It was found that the chelation-controlled arylation of 1 affords an expedient route for the conversion of phenols into arylacetaldehydes
Convenient preparation of mononuclear and dinuclear ruthenium hydride complexes for catalytic application
作者:Stefan Busch、Walter Leitner
DOI:10.1039/a906580f
日期:——
A mixture of commercially available [Ru(cod)(η3-C4H7)2] and PCy3 reacts with H2 to give [RuH2(H2)2(PCy3)2] in high yields, whereas [RuCy2P(CH2)3PCy2}(η3-C4H7)2] leads to [Cy2P(CH2)3PCy2}RuH(µ-H)3Ru(H2)Cy2P(CH2)3PCy2}] under identical conditions; this new synthetic procedure provides convenient access to this type of ruthenium hydrides for investigation of their potential in catalytic reactions like the Murai-reaction.
Investigations of the generality of quaternary ammonium salts as alkylating agents in direct C–H alkylation reactions: solid alternatives for gaseous olefins
C–H alkylation reactions using short chain olefins as alkylating agents could be operationally simplified on the lab scale by using quaternary ammonium salts as precursors for these gaseous reagents: Hofmann elimination delivers in situ the desired alkenes with the advantage that the alkene concentration in the liquid phase is high. In case a catalytic system did not tolerate the conditions for Hofmann
Quaternary Ammonium Salts as Alkylating Reagents in C–H Activation Chemistry
作者:Manuel Spettel、Robert Pollice、Michael Schnürch
DOI:10.1021/acs.orglett.7b01946
日期:2017.8.18
of benzylic amines via C(sp3)–H activation using quaternaryammoniumsalts as alkyl source is described. The reaction proceeds via in situ formation of an olefin via Hofmann elimination, which is the actual alkylating reagent. This represents an operationally simple method for substituting gaseous and liquid olefins with solid quaternaryammoniumsalts as alkylating reagents, which is transferable to
result of a compensation of steric and electronic effects associated with the bulkiness and to the polarizability, respectively, of R and/or R′. On the contrary, the basicity in concentrated sulfuric acid undergoes, along the same series of compounds, a variation of nearly 8 pK units, as a consequence of steric inhibition of solvation of the protonated carbonyl as the main effect played by R and/or R′.
由于补偿了空间和自由基,已发现许多烷基2,6-二烷基苯基酮(2,6-R 2 C 6 H 3 COR')的气相碱性几乎对结构变化不敏感。分别与R和/或R'的体积和极化率相关的电子效应。相反,在相同系列的化合物中,浓硫酸中的碱度变化接近8 p K由于R和/或R'所起的主要作用,是由于空间抑制质子化羰基的溶剂化而产生的。缩合阶段的结果与有关一些4-取代的2,6-二甲基苯乙酮和4-取代的苯乙酮的最新发现以及大量二烷基或烷基芳基酮的数据非常吻合(无论是从文献还是从得出整体p K BH +与m ∗的相关性(斜率= 8.8,n = 31,r= 0.996; 等式 (3)似乎具有普遍意义,并且至少在不存在强共轭相互作用的情况下,确定了对溶剂化的空间抑制作用是影响羰基碱度的常见因素。