Organic photochemistry. XV. Photochemistry of bichromophoric molecules. Intramolecular cycloaddition and cis-trans isomerization of 6-phenyl-2-hexene in solution
Controllable Isomerization of Alkenes by Dual Visible‐Light‐Cobalt Catalysis
作者:Qing‐Yuan Meng、Tobias E. Schirmer、Kousuke Katou、Burkhard König
DOI:10.1002/anie.201900849
日期:2019.4.16
We report herein that thermodynamic and kineticisomerization of alkenes can be accomplished by the combination of visible light with Co catalysis. Utilizing Xantphos as the ligand, the most stable isomers are obtained, while isomerizing terminal alkenes over one position can be selectively controlled by using DPEphos as the ligand. The presence of the donor–acceptor dye 4CzIPN accelerates the reaction
Reactions of ω-phenylalkenes with sulfur trioxide; sulfonation and Friedel-Crafts type of cyclization
作者:Ruud M. Schonk、Bert H. Bakker、Hans Cerfontain
DOI:10.1002/recl.19921110903
日期:——
Reactions of ω-phenylalkenes 1a-31a with sulfurtrioxide were studied in the temperature range −60 to 25°C using dichloromethane as solvent and 1.5 mol equiv. of dioxane as reactivity moderator. ω-Phenylalkenes 1a-7a react just like simple alkenes: at low temperature, they yield the (thermally unstable) β-sultones 1b-7b and 4c-7c, which at 25°C are converted into the corresponding carbyl sulfates.
displays high chemo- and stereoselectivity at full alkyne conversion to corresponding (Z)-olefins in the presence of an N-heterocycliccarbene (NHC) ligand. Solid-state NMR spectroscopy using the NHC ligand 13C-labeled at the carbenic carbon reveals a genuine coordination of the carbene to Cu NPs. The presence of distinct Cu surface environments and the coordination of the NHC to specific Cu sites likely
我们报告了一种表面有机金属路线,该路线在二氧化硅载体上生成铜纳米粒子 (NPs),同时用三甲基硅氧基团钝化二氧化硅表面。该材料对苯烷基-、二烷基-和二芳基-炔烃的催化半氢化具有活性,并在N-杂环卡宾 (NHC) 配体存在下将炔烃完全转化为相应的( Z )-烯烃时表现出高化学选择性和立体选择性。使用在卡宾碳上标记的 NHC 配体13 C 的固态 NMR 光谱揭示了卡宾与 Cu NPs 的真正配位。不同铜表面环境的存在以及 NHC 与特定铜位点的协调可能是提高选择性的原因。
A convenient coupling reaction of allyl alcohols with grignard reagents using 1-chloro-2-methyl-N,N-tetramethylenepropenylamine
作者:Tamotsu Fujisawa、Sachio Iida、Hisashi Yukizaki、Toshio Sato
DOI:10.1016/s0040-4039(00)94190-x
日期:1983.1
1-Chloro-2-methyl-N,N-tetramethylenepropenylamine was found to be a good condensation reagent for a regioselective coupling reaction of allyl alcohols with Grignard reagents under mild conditions to afford olefinic products.
of two different internal alkene isomers. The chromium catalyst, in the presence of HBpin/LiOtBu, enables the isomerization of alkenes over multiple carbon atoms to give the most thermodynamically stable isomers. The same catalyst allows for the selective isomerization of terminal alkenes over one carbon atom without an additive, exhibiting efficient and controllable alkene transposition selectivity
我们报告了一种单一的添加剂响应型铬催化系统,用于选择性生产两种不同的内部烯烃异构体中的任何一种。在 HBpin/LiO t Bu 存在下,铬催化剂能够使烯烃在多个碳原子上异构化,得到热力学最稳定的异构体。同一催化剂无需添加剂即可实现末端烯烃在一个碳原子上的选择性异构化,表现出高效且可控的烯烃转位选择性。