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
Development of a Palladium-Catalyzed Process for the Synthesis of<i>Z</i>-Alkenes by Sequential Sonogashira-Hydrogenation Reaction
作者:Sören Hancker、Helfried Neumann、Matthias Beller
DOI:10.1002/ejoc.201800651
日期:2018.10.17
A selective one‐pot protocol for the synthesis of Z‐alkenes via Sonogashira–semihydrogenation is reported. In this process the original homogeneous palladium catalyst is transformed into an active heterogeneous material.
A highly selective hydrogenation of alkynesusing an air-stable and readily available manganese catalyst has been achieved. The reaction proceeds under mild reaction conditions and tolerates various functional groups, resulting in (Z)-alkenes and allylic alcohols in high yields. Mechanistic experiments suggest that the reaction proceeds via a bifunctional activation involving metal–ligand cooperativity
Ligand-free (<i>Z</i>)-selective transfer semihydrogenation of alkynes catalyzed by <i>in situ</i> generated oxidizable copper nanoparticles
作者:Rafał Kusy、Karol Grela
DOI:10.1039/d1gc01206a
日期:——
of a semihydrogenation reaction results in the formation of a water-soluble ammonia complex, so that the catalyst may be reused several times by simple phase-separation with no need for any special regeneration processes. Formed NH4B(OR)4 can be easily transformed back into ammonia-borane or into boric acid. In addition, a one-pot tandem sequence involving a Suzuki reaction followed by semihydrogenation
在此,我们提出了在氢供体(如氨硼烷和绿色质子溶剂)存在下,基于原位生成的 CuNPs的炔烃的( Z ) 选择性转移半氢化。这种环保方法的特点是操作简单,同时具有高立体选择性和化学选择性以及官能团兼容性。CuNPs在半氢化反应完成后自动氧化形成水溶性氨络合物,因此催化剂可以通过简单的相分离多次重复使用,无需任何特殊的再生过程。形成NH 4 B(OR) 4可以很容易地转化回氨硼烷或硼酸。此外,还提出了涉及 Suzuki 反应和半氢化的一锅串联序列,这可以最大限度地减少化学废物的产生。
Methanol as the Hydrogen Source in the Selective Transfer Hydrogenation of Alkynes Enabled by a Manganese Pincer Complex
作者:Jan Sklyaruk、Viktoriia Zubar、Jannik C. Borghs、Magnus Rueping
DOI:10.1021/acs.orglett.0c02151
日期:2020.8.7
The first base metal-catalyzed transfer hydrogenation of alkynes with methanol is described. An air and moisture stablemanganesepincer complex catalyzes the reduction of a variety of different alkynes to the corresponding (Z)-olefins in high yields. The reaction is stereo- and chemoselective and scalable.