Rh(iii)-catalyzed, hydrazine-directed C-H functionalization with 1-alkynylcyclobutanols: a new strategy for 1H-indazoles.

Rh(III)-catalyzed coupling of phenylhydrazines with 1- alkynylcyclobutanols was realized through a hydrazine-directed C−H functionalization pathway. This [4+1] annulation, based on the cleavage of Csp-Csp triple bond in alkynylcyclobutanol, provides a new pathway to prepare diverse 1H-indazoles under mild reaction conditions.