Cascade reaction to 1H-pyrazoles from hydrazones via sodium Ni-trite promoted dual C–C/C–N formation, annulation and aromatization with 1,2-dichloroethane

Abstract A novel route for tandem C–C/C–N formation, annulation and aromatization of hydrazones with 1,2-dichloroethane to synthesize 1H-pyrazoles has been developed. Furthermore, the 1,2-dichloroethane serves as alkylation reagent in good to excellent yields. This methodology features mild reaction conditions and good functional group tolerance, providing a direct approach for the preparation of 1H-pyrazoles.