Sustainable multicomponent one pot synthesis of pyranopyrazole derivatives in the presence of Lactic acid: Urea: NH4Cl

Owing to the importance of pyranopyrazole scaffolds, several methods for their synthesis were developed. The previous reports on the synthesis of pyranopyrazole derivatives suffered many drawbacks which included difficulty in the workup, longer reaction time, high cost of catalyst and use of organic solvents. The present article reports the use of low melting mixture as a catalyst and solvent for the synthesis of pyranopyrazole derivatives. A study on the physical properties of the new Lactic Acid: Urea: NH4Cl low melting mixture such as density, viscosity, acidity, refractive index, surface tension is reported. IR spectra, 1H NMR spectra, emission spectra, polarity and cytotoxicity were also studied. The application in the synthesis of pyranopyrazole derivatives was established. The present method of synthesis of pyranopyrazole derivatives followed a simple procedure and easy workup protocol. The reaction was performed without the use of organic solvents. The components used in the mixture were easily available. The reaction required only less time and reactions were done at 28 ​°C. [Display omitted] •Lactic acid: Urea: NH4Cl low melting mixtures could take up two roles, catalyst and reaction media.•They possess characteristics such as low cost of components, easiness to prepare, low toxicity, bio renewability and biodegradability.•Many physicochemical properties of low melting mixtures performed includes thermal stability, glass transition temperature, density, viscosity, acidity, surface tension, refractive index, IR spectral studies and cytotoxicity•Lactic acid: Urea: NH4Cl low melting mixtures are recoverable and reusable.•The application towards synthesis of pyranopyrazole derivatives was very well performed