Phototransposition of Indazoles to Benzimidazoles: Tautomer-Dependent Reactivity, Wavelength Dependence, and Continuous Flow Studies.

ABSTRACT: Herein, we report a detailed investigation of the photomediated transformation of indazoles to benzimidazoles through a nitrogen-carbon transposition. This phototransposition is known to occur in low yield when 1H-indazoles are subjected to high-energy UVC irradiation. The 2H-tautomer of indazole absorbs light more strongly than the 1H-tautomer at longer wavelengths. We leveraged this improved absorbance profile to develop a general system for the high-yielding conversion of N2-derivatized indazoles (prepared from the corresponding 1H-indazoles) to the corresponding benzimidazoles under UVB or UVA irradiation in up to 98% yield. Investigation of the substrate scope revealed a strong correlation between reaction yield and electron density at N2 of the indazole substrate, suggesting the impo

SUBMITTER: Bartholomew GL 

PROVIDER: S-EPMC12307127 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature