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An efficient one pot synthesis of pyranopyrazoles has been achieved by the four-component condensation of hydrazine hydrate, ethyl acetoacetate, aldehydes and malononitrile using sodium lactate as a catalyst in aqueous ethanolic medium under reflux condition. The method is simple and green to afford pyranopyrazoles in a short time. It provides a new base catalyst that readily gives product from moderate to excellent yields.

Synthesis of 2,4,5-trisubstituted imidazole compounds from an aromatic aldehyde, benzil and ammonium acetate is demonstrated using biodegradable lactic acid at 160 °C. This method is a simple, environmentally benign, and works for aromatic aldehyde containing electron donating and electron withdrawing groups. Graphic abstractO Ph O Ph Ar-CHO CH 3 COONH 4 Lactic Acid N H N Ar Ph Ph

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Ammonium nickel sulphate [(NH 4 ) 2 SO 4 .NiSO 4 .6H 2 O] was found as a new catalyst to synthesis 2-aryl benzimidazole, 2-aryl benzothiazole and 2-aryl benzoxazole in aqueous media under sonication irradiation. The procedure is an eco-friendly, efficient and provides simple workup and good yield.