Three component solvent-free synthesis of 1H-pyrazol-5(4H)-one-based heterocyclic ketene aminal derivatives

An efficient one-pot three-component synthesis of novel 1H-pyrazol-5(4H)-one-based heterocyclic ketene aminal libraries was performed by simply refluxing a mixture of heterocyclic ketene aminals (HKAs), 1-phenyl-1H-pyrazol-5(4H)-ones and triethoxymethane under solvent-free and catalyst-free conditions. The protocol has the advantages of being highly efficient and environmentally benign, with excellent yields and easy work-up, making it suitable for large-scale and parallel combination synthesis. These compounds are promising candidates for drug discovery. Consequently, a library of diverse 1H-pyrazol-5(4H)-one-based HKAs was rapidly constructed using this method.