Stabilising fleeting intermediates of stilbene photocyclization with amino-borane functionalisation: the rare isolation of persistent dihydrophenanthrenes and their [1,5] H-shift isomers
作者:Yong-gang Shi、Soren K. Mellerup、Kang Yuan、Guo-Fei Hu、Francoise Sauriol、Tai Peng、Nan Wang、Pangkuan Chen、Suning Wang
DOI:10.1039/c8sc00560e
日期:——
The key intermediate, 4a,4b-dihydrophenanthrene (DPH), involved in the photocyclization of stilbene and derivatives is known to be unstable, and is therefore poorly characterized/understood. We have found that functionalising stilbenes with NMe2 and BMes2 groups can greatly enhance the stability of 4a,4b-DPHs, allowing quantitative isolation and full characterization of these rare species. Furthermore
已知参与二苯乙烯和衍生物光环化的关键中间体4a,4b-二氢菲(DPH)是不稳定的,因此表征/理解较差。我们发现,使用NMe 2和BMes 2基团官能化的斯蒂苯类化合物可以大大增强4a,4b-DPHs的稳定性,从而可以对这些稀有物种进行定量分离和全面表征。此外,我们发现新的氨基硼烷修饰的4a,4b-DPHs可以经历热[1,5] H的σ位移,形成异构体4a,10a-DPHs。4a,4b-DHP和4a,10a-DHP均对空气和湿气稳定,而只有前者在空气中365 nm照射后会发生氧化脱氢,产生明亮的蓝色/绿色荧光NMe 2和BMes 2功能化的菲类似物。对照研究确定,反-Mes 2 B–Ph–NMe 2单元负责这些分离的4a,4b-DHP及其[1,5] -H转移异构体的稳定性。