Compared with 1H-indazoles, 2H-indazoles have been much less studied in part due to the difficulty in their preparation. Most existing methods give mixtures of 1H- and 2H-indazoles,(4) and the selective preparation of 2H-indazoles remains challenging. Although recently several promising synthetic routes to 2H-indazoles have been reported,(5) the demand for new, efficient, and selective methods to prepare 2H-indazoles using readily available starting materials under mild ...
