The Head-to-Head ReductiveCoupling of Homoallylic Alcohols Promoted by Titanium(II)-OlefinComplexes
作者:Oleg G. Kulinkovich、Vladimir E. Isakov
DOI:10.1055/s-2003-39300
日期:——
main products in moderate to good yields. The head-to-head regioselectivity in reductive coupling of 4-penner-1-ol and 5-hexen-2-ol was also observed. Coupling of 2-methyl-5-hexen-2-ol, as well as unsaturated alcohols in which vinyl and hydroxyl groups are more distant from one another, proceeded with head-to-tail or tail-to-tail regioselectivity. It is supposed, that the unusual head-to-head regioselectivity
在 Ti(i-PrO) 4 存在下,高烯丙醇 1a-e 与 i-PrMgBr 的反应以中等至良好的产率得到了作为主要产物的未支化的饱和二醇 2a-e。还观察到 4-penner-1-ol 和 5-hexen-2-ol 还原偶联的头对头区域选择性。2-methyl-5-hexen-2-ol 和不饱和醇的偶联,其中乙烯基和羟基的距离更远,以头对尾或尾对尾区域选择性进行。据推测,高烯丙醇 1a-e 还原偶联中异常的头对头区域选择性是由于形成了具有两个稠合氧杂钛杂环戊烷环的关键钛环戊烷中间体 F 和 G。