Design and synthesis of <scp>Fsp³‐enriched spirocyclic‐substituted</scp> diarylpyrimidine derivatives as novel <scp>HIV</scp>‐1 <scp>NNRTIs</scp>

In this study, a novel series of diarylpyrimidine derivatives with Fsp³-enriched spirocycles were designed and synthesized to further explore the chemical space of the hydrophobic channel of the NNRTI-binding pocket. The biological evaluation results showed that most of the compounds displayed effective inhibitory potency against the HIV-1 wild-type strain, with EC₅₀ values ranging from micromolar to submicromolar levels. Among them, TT6 turned out to be the most effective inhibitor with an EC₅₀ value of 0.17 μM, demonstrating up to 47 times more active than that of reference drug 3TC (EC₅₀ = 8.01 μM). More encouragingly, TT6 was found to potently inhibit the HIV-1 mutant strain K103N with an EC₅₀ value of 0.69 μM, being about 6-fold more potent than 3TC (EC₅₀ = 3.68 μM) and NVP (EC₅₀ = 4.62 μM). Furthermore, TT6 exhibited the most potent inhibitory activity toward HIV-1 reverse transcriptase with an IC₅₀ value of 0.33 μM. Additionally, molecular simulation studies were conducted to investigate the binding modes between TT6 and NNRTI-binding pocket, which may provide valuable clues for the follow-up structural optimizations.