Grignard allylic substitution catalyzed by imidazol-2-ylidene- and imidazol-4-ylidene-magnesium complexes
作者:Sentaro Okamoto、Hiroyuki Ishikawa、Yoshimi Shibata、Yu-ichiro Suhara
DOI:10.1016/j.tetlet.2010.08.067
日期:2010.10
imidazolium salts, γ-substituted allyl chlorides reacted with alkyl Grignard reagents to undergo substitution reactions in an SN2′-selective fashion, where the magnesium ate complexes [(N-heterocyclic carbene-MgR3)−(MgX)+] of imidazol-2-ylidenes or imidazol-4-ylidenes, generated in situ, were postulated as the active species. It was observed that the reactions with imidazol-4-ylidene catalysts were faster
在催化量的1,2-二取代或1,2,3-三取代的咪唑鎓盐的存在下,γ-取代的烯丙基氯与烷基格氏试剂反应,以S N 2'-选择性方式进行取代反应,其中假定将原位生成的咪唑-2-亚胺或咪唑-4-亚胺的镁盐配合物[(N-杂环卡宾-MgR 3)-(MgX)+ ]作为活性物质。观察到与咪唑-4-亚烷基催化剂的反应比与咪唑-2-亚烷基催化剂的反应更快。初步研究了使用手性咪唑盐的对映选择性催化。