One-pot synthesis of highly functionalized pyrano[2,3-c]pyrazole-4,4′-diacetate and 6-oxo-pyrano[2,3-c]pyrazole derivatives catalyzed by urea

A facile one-pot, multicomponent protocol for the synthesis of 1,4-dihydro-pyrano[2,3-c]pyrazole derivatives using a urea catalyst is reported. This transformation proceeds via a four-component reaction of ethyl acetoacetate, a hydrazine, 3-oxo-pentanedioic acid dimethyl ester, and malononitrile. The bifunctional nature of urea means that it catalyzes many steps in this transformation, including domino Knoevenagel condensation, Michael addition, and ring opening and closing reactions. This synthetic method has several advantages, including good yield, simple work-up, harmless by-products, and simple purification.     

InCl3-catalyzed one-pot synthesis of multi-substituted pyrano[2,3-c]pyrazole-4-carboxylic acid esters under ultrasound irradiation

Molecular Diversity - An efficient and simple procedure for the synthesis of 6-amino-5-cyano-4-phenyl-pyrano[2,3-c]pyrazole-4-carboxylic acid esters was developed via a one-pot reaction of...