Davis-Beirut reaction: route to thiazolo-, thiazino-, and thiazepino-2H-indazoles.
- Author(s): Farber, Kelli M
- Haddadin, Makhluf J
- Kurth, Mark J
- et al.
Published Web Locationhttps://doi.org/10.1021/jo501014e
Methods for the construction of thiazolo-, thiazino-, and thiazepino-2H-indazoles from o-nitrobenzaldehydes or o-nitrobenzyl bromides and S-trityl-protected 1°-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.