Facile synthesis of dihydropyrimidinone derivatives via Biginelli reaction using Brønsted acidic ionic liquid [H-NMP]+[CH3SO3]- as an efficient homogeneous catalyst

In this research, a green, operationally simple, highly efficient and facile cascade Biginelli reaction using various aromatic aldehydes, ethyl acetoacetate, and urea/thiourea has been developed. First, the ionic liquid was prepared from the reaction of 1-methyl-2-pyrolidone with methane sulfonic acid. Then, this ionic liquid was applied as an acidic catalyst in the synthesis of dihydropyrimidinones as a target product under mild conditions. The ionic liquid and resulting products were characterized by physical and spectral data such as melting point, IR, 1HNMR and 13CNMR. The significant advantages of this protocol are short reaction time, excellent yields and easily available starting materials.