Divergent Regioselectivity in the Base-Promoted Reactions of Cyclic Eight-Membered α-Ketols with Activated Halides
作者:Leo A. Paquette、Ivan Vilotijevic、David Hilmey、Jiong Yang
DOI:10.1021/ol027315z
日期:2003.2.1
[reaction: see text] Deprotonation of 2-hydroxycyclooctanone followed by exposure to an allylic or benzylic halide proceeds very selectively to give the product of C-alkylation. The effect of Delta(5,6)-unsaturation is to promote instead the formation of the O-alkylated derivative. This crossover in kinetic preference is attributed to an inability of the olefinic system to attain a conformation conducive
[反应:见正文] 2-羟基环辛酮的去质子化,然后暴露于烯丙基或苄基卤化物,非常有选择性地进行,得到C-烷基化产物。Delta(5,6)-不饱和键的作用是促进O-烷基化衍生物的形成。动力学偏好上的这种交叉归因于烯烃系统无法获得有助于在C-2处质子抽象的构象。