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Synthesis of (2
 H
 )‐Indazoles from Azobenzenes Using Paraformaldehyde as a One‐Carbon Synthon

Rhodium(III)-catalyzed hydroxymethylation followed by intramolecular annulation of azobenzenes using paraformaldehyde as a valuable C1-feedstock is described. The method is readily extended to the coupling reaction between azobenzenes and trifluoroacetaldehyde. This transformation efficiently produces a range of C3-unsubstituted and C3-trifluoromethylated (2H)-indazoles, which are important targets in the development of novel bioactive compounds. Excellent chemoselectivity and functional group tolerance were observed. The synthetic transformation of C3-unsubstituted (2H)-indazoles highlights the utility of the developed method.