Conformational dependent regio- and stereo-selectivity in transformations of germacrenes
作者:Harrie R. Fransen、Guido J.M. Dormans、Henk M. Buck
DOI:10.1016/s0040-4020(01)92160-x
日期:——
Conformational calculations on 8-hydroxy-germacrene B 1 with the MNDO method led to a correct prediction of the most stable conformer. Reaction of 1 with diimide resulted in regio-selective reduction which leads to the formation of two racemic mixtures of 4,5-dihydro-8-hydroxy-germacrene B (2+3). The ratio of 2 and 3 could be predicted by conformational analysis The regioselectivity of the reduction
使用MNDO方法对8-羟基-germacrene B 1进行构象计算可正确预测最稳定的构象异构体。1与二酰亚胺的反应导致区域选择性还原,这导致形成4,5-二氢-8-羟基-锗茂B(2 + 3)的两种外消旋混合物。2和3的比例可以通过构象分析预测。还原的区域选择性可以归因于内环双键之间的sp 2 -sp 3扭转应变的差异。当LiAlH 4还原4,5-二氢-8-氧代-大黄烯B 10时构象诱导的不对称诱导导致高度立体定向的过程,其中以9:1的比例形成2和3。