Diastereomeric Discrimination in the Lifetimes of Norrish Type II Triplet 1,4-Biradicals and Stereocontrolled Partitioning of Their Reactivity (Yang Cyclization versus Type II Fragmentation)
作者:Jarugu Narasimha Moorthy、Apurba L. Koner、Subhas Samanta、Nidhi Singhal、Werner M. Nau、Richard G. Weiss
DOI:10.1002/chem.200600880
日期:2006.11.24
The stereochemistry at C2 and C3 carbons controls the partitioning of triplet 1,4-biradicals of ketones 2 among various pathways. Differences in the major reaction pathways, for example, cyclization (syn) and fragmentation (anti), adopted by the diastereomeric 1,4-radicals of ketones 2 have permitted unprecedented diastereomeric discrimination in their lifetimes to be observed by nanosecond laser flash
在C2和C3碳原子上的立体化学控制着酮2的三重态1,4-双自由基在各种途径之间的分配。酮2的非对映体1,4-自由基采用的主要反应途径(例如,环化(syn)和断裂(反))的差异允许通过纳秒激光闪光光解法观察到其寿命中空前的非对映体区别。从量子产率测量和瞬态寿命数据中,首次确定了一对非对映体三重态1,4-双自由基的环化和断裂的绝对速率常数。