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Abstract
The treatment of 4‐acetoacetyl derivative (3) of the pyrazoles with hydrazines in ethanol/HCl furnished a variety of bipyrazoles (4). However, when the reaction was performed in sodium acetate/acetic acid/ethanol, different hydrazines gave different products. Under these conditions an unexpected C‐C bond cleavage was observed thus affording a convenient route for the formation of pyrazolo‐5‐ols (5 and 6).
Acknowledgments
The authors are thankful to RSIC, Panjab University, Chandigarh (India) for NMR, IR and elemental analysis data. Financial help from CSIR, New Delhi (India) and Ranbaxy Research Laboratories, New Delhi (India) is gratefully acknowledged.