开发用于环境友好的有机转化的催化剂是一个非常活跃的研究领域。迄今为止报道的大多数催化剂都是基于过渡金属配合物。近年来,已经报道了由主族金属化合物催化的例子。在此,我们报告了一系列镁钳配合物,并通过 NMR 和 X 射线单晶衍射对其进行了表征。研究了通过芳构化/脱芳构化金属-配体合作对 H 2的可逆活化。利用所获得的配合物,在无碱条件下证明了前所未有的均相主族金属催化炔烃的半氢化和烯烃的氢化,得到Z-烯烃和烷烃分别作为产物,具有优异的收率和选择性。对照实验和 DFT 研究揭示了金属-配体合作参与氢化反应。该研究不仅为镁催化的炔烃半加氢和烯烃加氢提供了新途径,而且为主族金属配合物催化的其他化合物加氢提供了机会。
ylides derived from short-chain trialkylphosphines in the Wittig-type olefinationreactions toward the synthesis of alkenes, including stilbenes, styrenes, and 1,3-dienes, as well as reagents for homologation reactions, are described. The methods allow easy access to alkenes with high (E)-stereoselectivity in good yield. These reactions are conducted with weak bases in aqueous media, which allows easy
Electro‐mediated PhotoRedox Catalysis for Selective C(sp
<sup>3</sup>
)–O Cleavages of Phosphinated Alcohols to Carbanions
作者:Xianhai Tian、Tobias A. Karl、Sebastian Reiter、Shahboz Yakubov、Regina Vivie‐Riedle、Burkhard König、Joshua P. Barham
DOI:10.1002/anie.202105895
日期:2021.9.13
As well as deoxygenations, olefinations are reported which are E-selective and can be made Z-selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for an intimate dispersive precomplexation of its radical anion form with
Ni-Catalyzed regio- and stereoselective addition of arylboronic acids to terminal alkynes with a directing group tether
作者:Madala Hari Babu、Gadi Ranjith Kumar、Ruchir Kant、Maddi Sridhar Reddy
DOI:10.1039/c6cc10256e
日期:——
Addition of arylboronic acids to directing group tethered acetylenes in a regio and stereoselective manner using an inexpensive catalytic system is achieved for the first time to access highly sought after allyl/homoallyl alcohol/amine units.
<i>Z</i>-Selective Olefin Synthesis via Iron-Catalyzed Reductive Coupling of Alkyl Halides with Terminal Arylalkynes
作者:Chi Wai Cheung、Fedor E. Zhurkin、Xile Hu
DOI:10.1021/jacs.5b01784
日期:2015.4.22
Selective catalytic synthesis of Z-olefins has been challenging. Here we describe a method to produce 1,2-disubstituted olefins in high Z selectivity via reductive cross-coupling of alkylhalides with terminal arylalkynes. The method employs inexpensive and nontoxic catalyst (iron(II) bromide) and reductant (zinc). The substrate scope encompasses primary, secondary, and tertiaryalkylhalides, and
Highly Stereoselective and General Synthesis of (<i>E</i>)-Stilbenes and Alkenes by Means of an Aqueous Wittig Reaction
作者:James McNulty、Priyabrata Das
DOI:10.1002/ejoc.200900634
日期:2009.8
The chemoselective formation of trialkyl(benzylidene) ylides in water and their Wittigreaction with aromatic and aliphatic aldehydes provides a practical, stereoselective and environmentally benign route to valuable (E)-stilbenes and alkenes. The synthesis of the phytoalexin resveratrol is described. In addition, the method allows for a gram-scale synthesis of the anticancer agent DMU-212 utilizing