炔烃的立体选择性加氢构成构造立体烯烃的关键方法之一。大多数常规方法利用贵金属和有毒金属催化剂。这项研究涉及一种由工业化学品乙酰丙酮铁(II)和氢化二异丁基铝组成的简单催化剂,该催化剂能够在接近环境条件(1-3 bar H2、30°C,5 mol%[Fe] )。既不需要复杂的催化剂制备也不需要添加配体。机理研究(动力学中毒,X射线吸收光谱法,TEM)强烈表明了小铁簇和颗粒催化剂的运行。
The B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Catalyzed Tandem Meinwald Rearrangement–Reductive Amination
作者:Martine R. Tiddens、Robertus J. M. Klein Gebbink、Matthias Otte
DOI:10.1021/acs.orglett.6b01744
日期:2016.8.5
A system of three coupledcatalytic cycles enabling the one-pot transformation of epoxides to amines via Meinwald rearrangement, imine condensation, and iminereduction is described. This assisted tandem catalysis is catalyzed by B(C6F5)3 resulting in the first tandem Meinwald rearrangement–reductive amination protocol. The reaction proceeds in nondried solvents and yields β-functionalized amines.
描述了三个耦合的催化循环的系统,该系统能够通过Meinwald重排,亚胺缩合和亚胺还原将环氧化物一锅转化为胺。这种辅助的串联催化由B(C 6 F 5)3催化,从而产生了第一个串联的Meinwald重排-还原胺化方案。该反应在未干燥的溶剂中进行,并产生β-官能化的胺。特别地,以高收率获得β-二芳基胺。
Synthesis of stilbene analogues by one-pot oxidation-Wittig and oxidation-Wittig–Heck reaction
作者:Akeel S. Saiyed、Krupa N. Patel、Bola V. Kamath、Ashutosh V. Bedekar
DOI:10.1016/j.tetlet.2012.06.090
日期:2012.8
Synthesis of symmetrical (and unsymmetrical) stilbene derivatives is achieved by a combination of one-pot steps of Kornblum type oxidation of benzyl halide, its simultaneous in situ formation of phosphonium salt, and subsequently their Wittig reaction. In other variant it is oxidized to aldehyde, treated with ylide generated from phosphonium salt (CH3PPh3X) to give styrene, and subjected to Pd catalyzed
Diarylethenes were obtained from the corresponding ethenyl sulfones by photocatalyzed desulfonylation using UV or blue LEDs. When perylene and i-Pr2NEt were used as a photocatalyst and a sacrificing reagent, respectively, this desulfonylation proceeded smoothly to afford the desired ethenes with the functional groups such as chloro, alkoxy and heteroaromatic rings remaining untouched. The use of a flow photoreactor enabled this desulfonylation to proceed more rapidly to finish in an hour of residence time.
the catalytic epoxidation of para-substituted cis stilbenes 2a-i were investigated by using (R,R)-[N,N'-bis(3,5-di-tBu-salicylidene)-1,2-cyclohexanediamine]manganese(III) chloride 1 in benzene as the catalyst with iodosobenzene as the terminal oxidant. A Hammett study of the selectivity results reveals a stronger electrophilic character than previously assumed in the (salen)Mn-catalyzed reaction. In
N-graphitic-modified cobalt nanoparticles (Co/[email protected]2-800) are shown to be active in the semihydrogenation of alkynes to alkenes. Key to success for efficient catalysis is both the modification of the metal nanoparticles by nitrogen-doped graphitic layers and the use of silica as support. Several internal alkynes are converted to the Z isomer in high yields with up to 93% selectivity. In addition, a