Members of the catechol diether class are highly potent non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs). The most active compounds yield EC50 values below 0.5 nM in assays using human T-cells infected by wild-type HIV-1. However, these compounds like rilpivirine, the most recently FDA-approved NNRTI, bear a cyanovinylphenyl (CVP) group. This is an uncommon substructure in drugs that gives reactivity concerns. In the present work, computer simulations were used to design bicyclic replacements for the CVP group. The predicted viability of a 2-cyanoindolizinyl alternative was confirmed experimentally and provided compounds with 0.4-nM activity against the wild-type virus. The compounds also performed well with EC50 values of 10 nM against the challenging HIV-1 variant that contains the Lys103Asn/Tyr181Cys double mutation in the RT enzyme. Indolyl and benzofuranyl analogs were also investigated; the most potent compounds in these cases have EC50 values towards wild-type HIV-1 near 10 nM and high-nM activities towards the double-variant. The structural expectations from the modeling were much enhanced by obtaining an X-ray crystal structure at 2.88-Å resolution for the complex of the parent 2-cyanoindolizine 10b and HIV-1 RT. The aqueous solubilities of the most potent indolizine analogs were also measured to be ca. 40 µg/ml, which is similar to that for the approved drug efavirenz and ca. 1000-fold greater than for rilpivirine.

Catechol diether compounds have nanomolar antiviral and enzymatic activity against HIV with reverse transcriptase (RT) variants containing K101P, a mutation that confers high-level resistance to FDA-approved non-nucleoside inhibitors efavirenz and rilpivirine. Kinetic data suggests that RT (K101P) variants are as catalytically fit as wild-type and thus can potentially increase in the viral population as more antiviral regimens include efavirenz or rilpivirine. Comparison of wild-type structures and a new crystal structure of RT (K101P) in complex with a leading compound confirms that the K101P mutation is not a liability for the catechol diethers while suggesting that key interactions are lost with efavirenz and rilpivirine.

Non-nucleoside inhibitors of HIV-1 reverse transcriptase (HIV-RT) are reported that incorporate a 7-indolizinylamino or 2-naphthylamino substituent on a pyrimidine or 1,3,5-triazine core. The most potent compounds show below 10 nanomolar activity towards wild-type HIV-1 and variants bearing Tyr181Cys and Lys103Asn/Tyr181Cys resistance mutations. The compounds also feature good aqueous solubility. Crystal structures for two complexes enhance the analysis of the structure-activity data.