Eco-friendly Synthesis of Indole Conjugated Chromeno[d]Pyrimidines as Anti-cancer Agents and their Molecular Modelling Studies

Introduction Many medicinally active new chemical entities depend on indole conjugated chromeno[d]pyrimidine derivatives as a building block. The synthesis of 4-(1H-indol-3-yl)-3,4-dihydro-1H-chromeno[4,3-d]pyrimidine-2,5-dione 4 were achieved in the current study by treating 4-hydroxy-2H-chromen-2-one 1, indole aldehydes 2, and urea/thiourea 3 in the presence of L-proline. Methods By adopting the above protocol, we were able to synthesize eight compounds, i.e. 4-(1H-indol-3-yl)-3,4-dihydro-1H-chromeno[4,3-d]pyrimidine-2,5-diones (4a-4h), in the presence of L-proline as a catalyst in ethanol as solvent for 2-3 hours at 70-75 degrees C with decent yields of 80-85%, and their structures were ascertained by various spectral techniques. They were further screened for their potentiality to inhibit cancer growth in HepG2 and MDA-MD-231 cells. Results The scope of the synthesis of biological relevant Indole conjugated Chromeno[d]Pyrimidines by three-component reaction (MCRs) process was investigated. The most optimised conditions obtained were 0.3 eq of L-proline for 2 hours at 70-75 degrees C which gave the best yield (85%). The few advantages of this newly developed method are excellent yields, no metal catalyst, less toxic solvents, simple workup no chromatographic column purifications. On further screening for their anticancer activities, out of all, the compound 4b displayed noteworthy cytotoxicity with IC50 values of 8.1 and 9.2 mu M against HepG2 and MDA-MD-231, respectively. Additionally, in silico studies also supported that compound 4b had favourable binding energy (-7.8 kcal/mol) when compared to the co-crystal ligand (LS5) in inhibiting the human cyclin-dependent kinase 2 (CDK2) protein. Conclusion In conclusion, we have developed a simple, convenient, and efficient method for the synthesis of structurally diverse indole conjugated chromeno[d]pyrimidine analogues in the presence of L-proline as catalyst in ethanol as solvent with good yields. Further, the in vitro cytotoxic studies against HepG2 and MDA-MD-231 cells demonstrated that the synthesized compounds had good to reasonable activity, except for compound 4d.