通过相应硝基化合物的脱氧作用或相关叠氮化物的热解或光解反应制得的2-(2-硝基苯基)苯并噻唑通过攻击苯并噻唑氮而得到吲唑并[3,2- b ]苯并噻唑。在(2-(2-硝基苯基)苯并咪唑中,类似的氮原子侵蚀使得苯并咪唑并吲唑具有良好的收率。但是,在苯并咪唑中有适当的1-取代基(例如Me或CHMe 2)时,三重态(通过苯乙酮敏化的光解作用或带有4-二甲氨基的叠氮化物的热分解产生)的腈优先攻击该取代基得到苯并咪唑并喹唑啉。
Davis–Beirut Reaction: Route to Thiazolo-, Thiazino-, and Thiazepino-2H-indazoles
摘要:
Methods for the construction of thiazolo-, thiazino-, and thiazepino-2H-indazoles from o-nitrobenzaldehydes or o-nitrobenzyl bromides and S-trityl-protected 1 degrees-aminothioalkanes are reported. The process consists of formation of the requisite N-(2-nitrobenzyl) (tritylthio)alkylamine, subsequent deprotection of the trityl moiety with TFA, and immediate treatment with aq. KOH in methanol under Davis-Beirut reaction conditions to deliver the target thiazolo-, thiazino-, or thiazepino-2H-indazole in good overall yield. Subsequent S-oxidation gives the corresponding sulfone.