Water-acetic acid mediated chemoselective synthesis of pyrazolines via multimolecular domino reactions of enaminones and sulfonyl hydrazines

• Water-AcOH mediated domino reactions of enaminones and sulfonyl hydrazines.
• Unprecedented chemoselectivity to pyrazolines instead of pyrazoles.
• Novel pyrazoline products containing sulfonyl hydrazine side chain.
• No chromatographic purification.

The domino reactions between enaminones and sulfonyl hydrazines enabling novel synthesis of pyrazoline have been achieved by employing water as reaction medium and acetic acid as cheap and green additive are reported. Two new CN and one new CN bonds have been constructed during the formation of these pyrazoline scaffolds. Unlike the conventional formation of pyrazoles in the organic solvent mediated reactions of enaminones and hydrazines, the present reactions providing pyrazolines disclose new transformation pattern of enaminones by employing water as medium.

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