Microwave-assisted synthesis of coumarin-based 5,6-dihydro pyrimidin-2(1H)-one derivatives

Coumarin is an oxygen-containing heterocyclic compound of great medicinal important and high versatility in electronic and material science research. Incorporation of pyrimidine as a linker on coumarin is a way to provide improved application in solar cell research by extension of unsaturation for improved electronic transition. Convention synthesis approach is common in organic synthesis but have some disadvantages like affecting the eco-system due to discharge of toxic chemical during the process. On the other hand, microwave irradiation is eco-friendly and accelerates synthesis to afford great products following interesting reaction schemes and steps at reduced time. Hence, microwave assisted synthesis of novel coumarin-based 5,6-dihydropyrimidin-2(1H)-one derivatives was herein achieved via a three-step synthetic approach. The reaction was initiated with catalyst supported multicomponent reaction to produce 3-acetylcoumarin 7 which upon condensation with five aromatic aldehydes furnished chalcones 8a-e. Microwave assisted reaction of chalcones 8a-e with lone pair donor, urea led to the formation of the targeted coumarin-based 5,6-dihydropyrimidin-2(1H)-one 9a-e in good-to-excellent yields. The structures were established using spectroscopic data and notable physical properties and the results obtained were consistent with the expected structure of the products. The compounds will be good for further study to authenticate their applications in drug design and material science research. (paper)