Difluoromethylbenzoxazole pyrimidine thioether derivatives: a novel class of potent non-nucleoside HIV-1 reverse transcriptase inhibitors.

This paper reports the synthesis and antiviral properties of new difluoromethylbenzoxazole (DFMB) pyrimidine thioether derivatives as non-nucleoside HIV-1 reverse transcriptase inhibitors. By use of a combination of structural biology study and traditional medicinal chemistry, several members of this novel class were synthesized using a single electron transfer chain process (radical nucleophilic substitution, S(RN)1) and were found to be potent against wild-type HIV-1 reverse transcriptase, with low cytotoxicity but with moderate activity against drug-resistant strains. The most promising compound 24 showed a significant EC(50) value close to 6.4 nM against HIV-1 IIIB, a moderate EC(50) value close to 54 μM against an NNRTI resistant double mutant (K103N + Y181C), but an excellent selectivity index >15477 (CC(50) > 100 μM).