General synthesis of: 5‐substituted‐3‐acyl‐4‐carbethoxypyrazoles 3,6‐subslituted‐5‐carbethoxy‐4(h)pyridazinones and 3,7‐substitutedpyrazoio[3,4‐d] pyridazine‐4(5h)ones via reactions between 2‐hydroxy, methoxy, and acetoxy‐3(2h)furanones and hydrazine

Abstract

AbstractSynthesis of substituted 3‐acyl‐4‐carbethoxypyrazoles, 5‐earbethoxy‐4(1H)pyridazinones and pyrazolo[3,4‐d]pyridazine‐4(5H)ones is described. They involve the reaction of the 2,5‐substituted‐4‐earbelhoxy‐2‐hydroxy, methoxy and acetoxy‐3(2H)furanones with hydrazine hydrate. The reaction was found to be dependent on the hydroxy, methoxy or acetoxy substituents of these furanones and proceeds with ring opening followed by cy clisation. Pyrazoles were formed with hydroxy or methoxy substituents while pyridazinones are afforded with acetoxy group. The pyrazoles so formed were readily converted to pyrazolo[3,4‐d] pyridazinones by condensation with excess hydrazine.