A convergent method for the stereoselective synthesis of trisubstituted alkenes
摘要:
A method for the stereoselective, convergent synthesis of trisubstituted alkenes has been developed. The procedure features the synthesis of allylic alcohols 9 by coupling an aldehyde with a vinyl organometallic reagent. Treatment of 9 with carbon disulfide and methyl iodide gave the intermediate allylic xanthates 10 that underwent facile [3,3]-sigmatropic rearrangement to give the dithiocarbonates 11 and 12, radical reduction of which gave the (E)-alkenes 13 as the major products.
Nickel-Catalyzed Heck-Type Reactions of Benzyl Chlorides and Simple Olefins
作者:Ryosuke Matsubara、Alicia C. Gutierrez、Timothy F. Jamison
DOI:10.1021/ja209235d
日期:2011.11.30
Nickel-catalyzed intermolecular benzylation and heterobenzylation of unactivated alkenes to provide functionalized allylbenzene derivatives are described. A wide range of both the benzylchloride and alkene coupling partners are tolerated. In contrast to analogous palladium-catalyzed variants of this process, all reactions described herein employ electronically unbiased aliphatic olefins (including
Thiourea–I2 as Lewis base–Lewis acid cooperative catalysts are developed for the iodochlorination of alkenes with in situ-generated iodinemonochloride (I–Cl). The Lewis base–Lewis acid cooperative system is sufficient to generate I–Cl from I2 with a chlorinating reagent at low temperature. Based on the solid-state structure of the active species, thiourea–I2 cooperatively captures I–Cl. By taking
硫脲-I 2作为路易斯碱-路易斯酸协同催化剂被开发用于用原位生成的一氯化碘(I-Cl)进行烯烃的碘氯化。刘易斯碱-路易斯酸协同体系足以在低温下用氯化剂从I 2生成I-Cl 。基于活性物质的固态结构,硫脲I 2协同捕获I Cl。通过利用I–Cl生成和在低温下控制I–Cl的优势,硫脲– I 2协同系统抑制了由高反应性游离I–Cl引起的副反应。
Simplifying Nickel(0) Catalysis: An Air-Stable Nickel Precatalyst for the Internally Selective Benzylation of Terminal Alkenes
作者:Eric A. Standley、Timothy F. Jamison
DOI:10.1021/ja3116718
日期:2013.1.30
The synthesis and characterization of the air-stable nickel(II) complex trans-(PCy2Ph)(2)Ni(o-tolyl)Cl is described in conjunction with an investigation of its use for the Mizoroki-Heck-type, room temperature, internally selective coupling of substituted benzyl chlorides with terminal alkenes. This reaction, which employs a terminal alkene as an alkenylmetal equivalent, provides rapid, convergent access to substituted allylbenzene derivatives in high yield and with regioselectivity greater than 95:5 in nearly all cases. The reaction is operationally simple, can be carried out on the benchtop with no purification or degassing of solvents or reagents, and requires no exclusion of air or water during setup. Synthesis of the precatalyst is accomplished through a straightforward procedure that employs inexpensive, commercially available reagents, requires no purification steps, and proceeds in high yield.
Direct one-pot synthesis of terminal olefins and deuterio olefins from carboxylic acid chlorides
作者:Jose Barluenga、Miguel Yus、Jose M. Concellon、Pablo Bernad