Synthesis, cytotoxicity and hDHFR inhibition studies of 2H-pyrido[1,2-a]pyrimidin-2-ones

Synthesis of the titled scaffolds was achieved by the condensation of Baylis–Hillman acetates with 2-aminopyridines under solvent-free conditions. Resulting compounds were evaluated for anticancer activity against five different cancer cell lines. Compounds 3c–g displayed low-micromolar inhibition with IC50 values ranging from 0.86 to 0.94 μM, and 3b, 3h, 3i and 3j between 8.6 and 9.8 μM against a neuroblastoma cell line (SK-n-SH). 3b, 3i and 3j inhibited the proliferation of breast cancer cells (MCF-7) at 10 μM. hDHFR inhibitory studies produced IC50 values of 2.7 and 3.1 μM for 3i and 3j, and 8.7 μM for 3o. Molecular docking studies established the mode of binding of these compounds into the methotrexate binding pocket of hDHFR. Structure–activity relationship studies indicate a clear preference for some substitutions over others.