Arpa Enrique M, Stafström Sven, Durbeej Bo
Division of Theoretical Chemistry, IFM, Linköping University, 58183 Linköping, Sweden.
Institute of Organic Chemistry, RWTH Aachen University, 52056 Aachen, Germany.
Phys Chem Chem Phys. 2024 Apr 17;26(15):11295-11305. doi: 10.1039/d4cp00777h.
Photochemical reactions enabling efficient transformation of aromatic systems into energetic but stable non-aromatic isomers have a long history in organic chemistry. One recently discovered reaction in this realm is that where derivatives of 1,2-azaborine, a compound isoelectronic with benzene in which two adjacent C atoms are replaced by B and N atoms, form the non-hexagon Dewar isomer. Here, we report quantum-chemical calculations that explain both why 1,2-azaborine is intrinsically more reactive toward Dewar formation than benzene, and how suitable substitutions at the B and N atoms are able to increase the corresponding quantum yield. We find that Dewar formation from 1,2-azaborine is favored by a pronounced driving force that benzene lacks, and that a large improvement in quantum yield arises when the reaction of substituted 1,2-azaborines proceeds without involvement of an intermediary ground-state species. Overall, we report new insights into making photochemical use of the Dewar isomers of aromatic compounds.
在有机化学领域，能使芳香体系高效转化为高能但稳定的非芳香异构体的光化学反应由来已久。该领域最近发现的一个反应是，1,2 - 氮杂硼苯（一种与苯等电子体的化合物，其中两个相邻的碳原子被硼和氮原子取代）的衍生物形成非六边形的杜瓦异构体。在此，我们报道了量子化学计算结果，这些计算结果既解释了为什么1,2 - 氮杂硼苯比苯本身对形成杜瓦异构体更具反应活性，也解释了在硼和氮原子上进行适当取代如何能够提高相应的量子产率。我们发现，1,2 - 氮杂硼苯形成杜瓦异构体受到苯所缺乏的显著驱动力的青睐，并且当取代的1,2 - 氮杂硼苯的反应在不涉及中间基态物种的情况下进行时，量子产率会有大幅提高。总体而言，我们报告了关于光化学利用芳香化合物杜瓦异构体的新见解。
