Roth Alexander D, Thamattoor Dasan M
Department of Chemistry, Colby College, Waterville, ME 04901, USA.
Org Biomol Chem. 2023 Dec 13;21(48):9482-9506. doi: 10.1039/d3ob01525d.
Although a ripe old discipline by now, carbene chemistry continues to flourish as both theorists and experimentalists have shown sustained interest in this area of research. While there are numerous ways of generating carbenes, the thermal and/or photochemical decomposition of diazo compounds and diazirines remains, by far, the most commonly used method of producing these intermediates. There is no disputing the fact that these nitrogenous precursors have served carbene researchers well, but their use is not without problems. They are often sensitive and hazardous to handle and, sometimes, the desired nitrogenous precursor simply may not be available, , for synthetic reasons, to study the particular carbene of interest. Furthermore, there is a legitimate concern that the photochemical generation of carbenes in solution from diazo compounds and diazirines may be contaminated by reactions in the excited states (RIES) of the precursors themselves. As an alternative, several laboratories, including ours, have used cyclopropanated aromatic systems to generate a wide range of carbenes. In each case, the cheleotropic extrusion of carbenes is accompanied by the formation of stable aromatic by-products such as phenanthrene, indane, naphthalene, and 1,4-dihydronaphthalene. The emergence of these "non-traditional" carbene sources, their versatility, and promise are reviewed in this work.
尽管卡宾化学如今已是一门成熟的学科，但由于理论家和实验家都对这一研究领域保持着持续的兴趣，它仍在蓬勃发展。虽然生成卡宾有多种方法，但迄今为止，重氮化合物和二氮杂环丙烷的热分解和/或光化学分解仍然是制备这些中间体最常用的方法。毫无疑问，这些含氮前体对卡宾研究人员帮助很大，但它们的使用并非没有问题。它们往往对处理敏感且具有危险性，而且有时，出于合成原因，所需的含氮前体可能根本无法获得，无法用于研究感兴趣的特定卡宾。此外，人们有合理的担忧，即重氮化合物和二氮杂环丙烷在溶液中光化学生成卡宾可能会被前体自身的激发态反应（RIES）污染。作为一种替代方法，包括我们实验室在内的几个实验室已经使用环丙烷化的芳香体系来生成多种卡宾。在每种情况下，卡宾的螯合挤出都伴随着稳定的芳香副产物的形成，如菲、茚、萘和1,4 - 二氢萘。本文将对这些“非传统”卡宾源的出现、它们的多功能性及前景进行综述。
