Hindered organoboron groups in organic chemistry. 25. The condensation of aliphatic aldehydes with dimesitylboryl stabilised carbanions to give alkenes.
作者:Andrew Pelter、Keith Smith、Said M.A. Elgendy
DOI:10.1016/s0040-4020(01)87983-7
日期:1993.8
In the presence of protic acids the condensation of aliphatic aldehydes with dimesitylboryl stabilised carbanions results in alkenes. In the presence of strong acids such as HCl or CF3SO3H, the products contain > 90% of E-alkenes in all cases tried. When acetic acid is used, then Z-alkenes may result predominantly, particularly in the cases of RsCHO and RtCHO. HX HCI, CF3SO3H gives E - alkenes in
在质子酸的存在下,脂族醛与二聚三苯甲基稳定的碳负离子的缩合会生成烯烃。在强酸(例如HCl或CF 3 SO 3 H)的存在下,在所有尝试的情况下,产品均含有> 90%的E-烯烃。当使用乙酸时,则可能主要产生Z-烯烃,特别是在R s CHO和R t CHO的情况下。在所有情况下,HXHCl,CF 3 SO 3 H均会生成E-烯烃。HXCH 3 CO 2 H,使得主要ž -烯烃当Rř秒,R叔。
Hindered organoboron groups in organic synthesis. 14. stereoselective synthesis of alkenes by the boron-wittig reaction using aliphatic aldehydes
In the presence of HX, carbanions Mes2BCHLiR1 react with aliphatic aldehydes to give alkenes. The stereochemistry of the product alkene depends upon the nature of HX.
Iron-Catalyzed Tunable and Site-Selective Olefin Transposition
作者:Xiaolong Yu、Haonan Zhao、Ping Li、Ming Joo Koh
DOI:10.1021/jacs.0c08631
日期:2020.10.21
earth-abundant iron-based complex, a base and a boryl compound promote efficient and controllable alkene transposition. Mechanistic investigations reveal that these processes likely involve in situ formation of an iron-hydride species which promotes olefin isomerization through sequential olefin insertion/β-hydride elimination. Through this strategy, regiodivergent access to different products from
CC 双键的催化异构化是必不可少的化学转化,用于提供更高价值的类似物,在化学工业中具有重要用途。尽管在该领域取得了进展,但仍然迫切需要一种通用催化解决方案,能够精确控制环状和非环状体系中的 C=C 键迁移位置,以提供二取代和三取代烯烃。在这里,我们展示了催化量的合适的地球丰富的铁基络合物、碱和硼基化合物促进有效和可控的烯烃转位。机理研究表明,这些过程可能涉及原位形成铁氢化物物种,该物种通过顺序烯烃插入/β-氢化物消除促进烯烃异构化。通过这个策略,
Highly chemo- and stereoselective Fe-catalyzed alkenylation of organomanganese reagents
作者:Gérard Cahiez、Sophie Marquais
DOI:10.1016/0040-4039(96)00116-5
日期:1996.3
Organomanganese chlorides react with alkenyl iodides, bromides and chlorides in the presence of 3% Fe(acac)3. The reaction takes place under very mild conditions (THF-NMP, rt, 1h) to afford the substituted olefin in excellent yields with a high stereo- and chemoselectivity. Thus an unprotected keto alkenyl chloride selectively gives the corresponding keto olefin. From a preparative point of view, this
Visible‐Light Controlled Divergent Catalysis Using a Bench‐Stable Cobalt(I) Hydride Complex
作者:Enrico Bergamaschi、Frédéric Beltran、Christopher J. Teskey
DOI:10.1002/chem.202000410
日期:2020.4.21
the ability to switch the actual function of the catalyst and resulting products. Here we report such an example of multi-dimensional catalysis. Featuring an easily prepared, bench-stable cobalt(I) hydride complex in conjunction with pinacolborane, we can switch the reaction outcome between two widely employed transformations, olefin migration and hydroboration, with visible light as the trigger.