Bond Rotation Dynamics of Enamides: The Effect of the Acyl Group and Potential for Chirality Transfer during 5-Endo Trig Radical Cyclizations
作者:Andrew J. Clark、Dennis P. Curran、Joanna V. Geden、Natalie James、Paul Wilson
DOI:10.1021/jo200343z
日期:2011.6.3
compared to nonpolar solvents such as toluene. The barrier to rotation of “mimics” for acetamide-based radicals are estimated. The relative order of the values of krot for different acyl groups parallels their reported Taft Es paramaters. For successful chirality transfer in 5-endo trig radical cyclization, it is evident that rotations would need to be significantly slower than those reported here.
已经通过可变温度NMR实验在不同溶剂中测量了一系列N-环烯基-N-苄基乙酰胺衍生物中N-烯基键旋转的障碍。阻挡层的范围为9.7至14.2 kcal / mol,这取决于乙酰胺酰基上的取代基。与非极性溶剂(例如甲苯)相比,诸如氯仿和甲醇之类的极性溶剂会增加旋转的障碍。估计了基于乙酰胺基的“模拟物”旋转的障碍。不同酰基的k rot值的相对顺序与其报道的Taft E s参数平行。在5- endo trig中成功进行手性转移 自由基环化,很明显,旋转速度必须比此处报道的旋转速度明显慢。