Microwave assisted synthesis of dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-ones; synthesis, in vitro antimicrobial and anticancer activities of novel coumarin substituted dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-ones

• 3 novel dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-ones were synthesized.
• 8 coumarin substituted dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-ones were synthesized.
• Crystal structure of compound 4b was determined.
• Compound 4g showed potent cytotoxic activity against DAL cell line.

The present article describes the synthesis of dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-one (2a–h) under microwave irradiation. The product was obtained in excellent yield (74–94%) in a shorter reaction time (2 min). These molecules (2a, b) further reacted with various substituted 4-bromomethylcoumarins (3a–f) to yield a new series of coumarin substituted dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-ones (4a–h). The structure of all the synthesized compounds were confirmed by spectral studies and screened for their in vitro antibacterial activity against three Gram-positive bacteria viz., Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans and three Gram-negative bacteria viz., Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and antifungal activity against Candida albicans, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, Fusarium oxysporum, Penicillium chrysogenum and anticancer activity against Dalton's Ascitic Lymphoma (DAL) cell line.In general, all the compounds possessed better antifungal properties than antibacterial properties. The coumarin substituted dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-one (4g) (R = i-Pr, R1 = 6-Cl) was found to be the most potent cytotoxic compound (88%) against Dalton's Ascitic Lymphoma cell line at the concentration of 100 μg/mL.

The coumarin substituted dihydrobenzo[4,5]imidazo[1,2-a]pyrimidin-4-one (4g) was found to be the most potent cytotoxic compound (88%). The structure of the compound (4b) was confirmed by single crystal diffraction analysis. Figure optionsDownload as PowerPoint slide