Access to 1H-indazoles, 1H-benzoindazoles and 1H-azaindazoles from (het)aryl azides: a one-pot Staudinger-aza-Wittig reaction leading to N–N bond formation?

The synthesis of various substituted 1H-indazoles is reported through N–N bond formation from an iminophosphorane derivative. Supported by control experiments, an original Staudinger-aza-Wittig tandem mechanism is proposed for this transformation.