Experimental and Theoretical Characterization of the Valence Isomerization of Bi-2H-azirin-2-yls to Diazabenzenes
作者:Klaus Banert、Stefan Grimme、Rainer Herges、Kirsten Heß、Frank Köhler、Christian Mück-Lichtenfeld、Ernst-Ulrich Würthwein
DOI:10.1002/chem.200600318
日期:2006.9.25
4-diazidocyclobutenes 16 were prepared from the corresponding dihalides. Some of these diazides, such as parent compound 16 d and phenyl-substituted derivatives 16 c,f, underwent spontaneous stereoselective electrocyclic ring opening below room temperature, whereas the tetraalkyl derivatives of 16 had to be heated to force the same reaction. In most cases, the resulting 1,4-diazidobuta-1,3-dienes 8 were isolated
由相应的二卤化物制备3,4-二叠氮基环丁烯16。这些重氮化合物中的一些,例如母体化合物16d和苯基取代的衍生物16c,f,在室温以下进行自发的立体选择性电环开环,而必须加热16的四烷基衍生物以强制进行相同的反应。在大多数情况下,分离得到的1,4-二氮杂丁-1,3-二烯8以研究它们通过中间体单叠氮基17的光化学转化为bi-2H-azirin-2-yls 9的方法。在许多取代基如9 d和9 f上,标题化合物9经历了热价异构化,仅在令人惊讶的低温下导致哒嗪18。根据在UB3LYP / 6-31 + G(d)和MR-MP2 / TZV(2df,2p)水平上母体bi-2H-azirinyl-2-yl 9 d的量子化学计算,化合价过程为最好的解释是通过同时均裂裂解9个C-N单键以生成能量上有利的N,N'双自由基26,这些自由基环化成18。理论研究还表明9的一种立体异构体,即rac化合物,应进行价态异构