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 radicals derived 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
单环2-苯基-1,3-二恶烷-2-基的开环β-断裂优先给出更稳定的烷基。然而,衍生自两个4,6- O-亚苄基吡喃葡萄糖苷的类似双环自由基优先于仲自由基提供伯自由基,其结果可借助DFT计算来合理化。Barton和Subramanian的报告指出,由氢化锡介导的相应糖基硫代碳酸碳根的还原性开环所产生的相反的区域选择性是错误的。