Synthesis of<i>trans</i>-Disubstituted Alkenes by Cobalt-Catalyzed Reductive Coupling of Terminal Alkynes with Activated Alkenes
作者:Subramaniyan Mannathan、Chien-Hong Cheng
DOI:10.1002/chem.201200779
日期:2012.9.10
CoCl2/P(OPh)3/Zn system providing a mixture of 1,2‐trans‐ and 1,1‐disubstituted functionalized terminal alkene products in high yields. The scope of the reaction was also extended by the coupling of 1,3‐enynes and acetylene gas with alkenes. Furthermore, a phosphine‐free cobalt‐catalyzed reductive coupling of terminal alkynes with enones, affording 1,2‐trans‐disubstituted alkenes as the major products in a high regioisomeric
末端炔烃,RCCH,与活化的链烯烃,R'CHCH的钴催化的还原偶联2,在锌和水的存在下,得到官能化的反式二取代的烯烃,RCHCHCH 2 CH 2 R',是描述。在CoCl 2 / P(OMe)3 / Zn催化剂体系存在下,各种芳族末端炔与活化的烯烃(包括烯酮,丙烯酸酯,丙烯腈和乙烯基砜)进行还原偶联,得到1,2-反式具有高区域和立体选择性的二取代烯烃。同样,在存在CoCl 2 / P(OPh)3 / Zn体系的情况下,脂族末端炔烃也有效地参与了与丙烯酸酯,烯酮和乙烯基砜的偶联反应,从而提供了1,2-反式和1, 1-二取代的官能化末端烯烃产品,收率高。通过将1,3-炔烃和乙炔气与烯烃的偶联反应也扩大了反应范围。此外,末端炔烃与烯酮的无膦钴催化还原偶联,可得到1,2-反式证明了以高区域异构体比例为主要产物的二取代烯烃。在反应中,使用了较便宜且空气稳定的钴配合物,温和的还原剂(Zn)和简