的产生和2命运I-VII,3 I-VII,6 II-VII -icosa- ø -甲基- β-cyclomaltoheptaos-6我- ö还原条件下基自由基进行说明。涉及两个自由基级联反应:主要的一个是在5 VII C由氢的1,8-HAT引发。该自由基可以通过六步顺序在三个糖单元之前于1 V C到达异头氢。在5组14个氢化物允许一个选择性地停止所述级联的不同供氢能力VII C,2 VI C,和4 VI ℃以得到β-CD与β-升-Ido p 单元,无环七糖和六糖结构。
Regioselectivity in the ring opening of 2-phenyl-1,3-dioxan-2-yl radicals derived from cyclic benzylidene acetals and comparison with deoxygenation of a carbohydrate diol via its cyclic thionocarbonate
作者:Brian P Roberts、Teika M Smits
DOI:10.1016/s0040-4039(01)00540-8
日期:2001.5
Ring-opening β-scission of monocyclic 2-phenyl-1,3-dioxan-2-yl radicals gives preferentially the more stabilised alkyl radical. However, analogous bicyclic radicalsderived from two 4,6-O-benzylidene glucopyranosides afford primary radicals in preference to secondary radicals, a result that can be rationalised with the aid of DFT calculations. The report by Barton and Subramanian, that the opposite