Design, synthesis, biological evaluation and docking studies of novel 2-substituted-4-morpholino-7,8-dihydro-5H-thiopyrano[4,3-d]pyrimidine derivatives as dual PI3Kα/mTOR inhibitors.

Four series of 2-substituted-4-morpholino- 7,8-dihydro-5H-thiopyrano[4,3-d]pyrimidine derivatives (9-28) were designed, synthesized and their structures were confirmed by (1)H NMR, (13)C NMR and MS spectrum. All compounds were evaluated for the IC50 values against three cancer cell lines (A549, PC-3 and MCF-7). And four selected compounds (10, 11, 24, 27) were further evaluated for the IC50 values against PI3Kα and mTOR kinases. Seven of the target compounds exhibited moderate to excellent antitumor activities against these three cancer cell lines. The most promising compound 11 showed good antitumor potency for A549, PC-3 and MCF-7 cell lines with IC50 values of 0.52 ± 0.10 μM, 1.41 ± 0.10 μM, 4.82 ± 0.24 μM and moderate antitumor activities against PI3Kα/mTOR with IC50 values of 6.72 ± 0.30 μM and 0.94 ± 0.10 μM. Structure-activity relationships (SARs) and docking studies indicated that aryl urea scaffolds had a significant impact on the antitumor activities, and aryl pyridine urea scaffolds produced the best potency. Variations in substitutions of the aryl group had a significant impact on the activity and 3-Cl-4-F or 3-CF3-4-Cl substitution was more preferred.