Department of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3, Machikaneyama-cho, Toyonaka, Osaka, 560-8531, Japan.
Chemistry. 2018 Aug 6;24(44):11278-11282. doi: 10.1002/chem.201801972. Epub 2018 Jul 16.
A metal-free deoxygenation and reductive disilylation of nitroarenes was achieved using N,N'-bis(trimethylsilyl)-4,4'-bipyridinylidene (1) under mild and neutral reaction conditions, and a broad functional group tolerance was possible in this reaction. Mono-deoxygenation, giving a synthetically valuable N,O-bis(trimethylsilyl)phenylhydroxylamine (7 a) as a readily available and safe phenylnitrene source from nitrobenzene, and double-deoxygenation, giving N,N-bis(trimethylsilyl)anilines 8, were easily controlled by varying the amounts of 1 and reaction temperature as well as adding dibenzothiophene (DBTP). Reaction of 2-arylnitrobenzenes with 1 resulted in the formation of the corresponding carbazoles 14 via in situ-generated phenylnitrene species derived by thermolysis of N,O-bis(trimethylsilyl)phenylhydroxylamines 7, followed by their subsequent intramolecular C-H insertion. In addition, the intramolecular N-N coupling reaction proceeded in the reduction of 2,2'-dinitrobiphenyl derivatives by 1, giving the corresponding benzo[c]cinnolines.
一种使用 N,N'-双(三甲基硅基)-4,4'-联吡啶基二亚基(1)在温和中性反应条件下实现的无金属脱氧和还原双硅烷基化硝基芳烃的方法，该反应具有广泛的官能团容忍性。单脱氧，可从硝基苯中得到合成上有价值的 N,O-双(三甲基硅基)苯羟胺(7a)，作为一种容易获得且安全的苯亚硝胺源，而双脱氧，可得到 N,N-双(三甲基硅基)苯胺 8，通过改变 1 的用量、反应温度以及添加二苯并噻吩(DBTP)，很容易控制。2-芳基硝基苯与 1 反应，通过 N,O-双(三甲基硅基)苯羟胺 7 热解原位生成的苯亚硝胺，随后进行后续的分子内 C-H 插入，形成相应的咔唑 14。此外，在 1 还原 2,2'-二硝基联苯衍生物时，发生分子内 N-N 偶联反应，得到相应的苯并[c]茚啉。
