Structure-Based Design of Potent HIV‑1 Protease Inhibitors with Modified P1-Biphenyl Ligands: Synthesis, Biological Evaluation, and Enzyme–Inhibitor X‑ray Structural Studies

We report the design, synthesis, X-ray structural studies, and biological evaluation of a novel series of HIV-1 protease inhibitors. We designed a variety of functionalized biphenyl derivatives to make enhanced van der Waals interactions in the S1 subsite of HIV-1 protease. These biphenyl derivatives were conveniently synthesized using a Suzuki–Miyaura cross-coupling reaction as the key step. We examined the potential of these functionalized biphenyl-derived P1 ligands in combination with 3-(<i>S</i>)-tetrahydrofuranyl urethane and bis-tetrahydrofuranyl urethane as the P2 ligands. Inhibitor <b>21e</b>, with a 2-methoxy-1,1′-biphenyl derivative as P1 ligand and bis-THF as the P2 ligand, displayed the most potent enzyme inhibitory and antiviral activity. This inhibitor also exhibited potent activity against a panel of multidrug-resistant HIV-1 variants. A high resolution X-ray crystal structure of related Boc-derivative <b>17a</b>-bound HIV-1 protease provided important molecular insight into the ligand-binding site interactions of the biphenyl core in the S1 subsite of HIV-1 protease

Simultaneous Online Monitoring of Multiple Reactions Using a Miniature Mass Spectrometer

Advances in chemical sampling using miniature mass spectrometer technology are used to monitor slow reactions at a frequency of ca. 180 h^–1 (on the Mini 12) with no sample carryover and with inline derivatization in the case of poorly ionizing compounds. Moreover, we demonstrate high reproducibility with a relative error of less than 10% for major components. Monitoring is enabled using a continuous-flow nanoelectrospray (CF-nESI) probe contained in a custom-built 3D-printed rotary holder. The holder position is automatically set using a stepper motor controlled by a microcontroller. Reaction progress of up to six reactions, including hydrazone formation and Katritzky transamination, can be monitored simultaneously without carryover for several hours

Highly Potent HIV‑1 Protease Inhibitors with Novel Tricyclic P2 Ligands: Design, Synthesis, and Protein–Ligand X‑ray Studies

The design, synthesis, and biological evaluation of a series of HIV-1 protease inhibitors incorporating stereochemically defined fused tricyclic P2 ligands are described. Various substituent effects were investigated to maximize the ligand-binding site interactions in the protease active site. Inhibitors <b>16a</b> and <b>16f</b> showed excellent enzyme inhibitory and antiviral activity, although the incorporation of sulfone functionality resulted in a decrease in potency. Both inhibitors <b>16a</b> and <b>16f</b> maintained activity against a panel of multidrug resistant HIV-1 variants. A high-resolution X-ray crystal structure of <b>16a</b>-bound HIV-1 protease revealed important molecular insights into the ligand-binding site interactions, which may account for the inhibitor’s potent antiviral activity and excellent resistance profiles

Design and Synthesis of Highly Potent HIV‑1 Protease Inhibitors Containing Tricyclic Fused Ring Systems as Novel P2 Ligands: Structure–Activity Studies, Biological and X‑ray Structural Analysis

The design, synthesis, and biological evaluation of a new class of HIV-1 protease inhibitors containing stereochemically defined fused tricyclic polyethers as the P2 ligands and a variety of sulfonamide derivatives as the P2′ ligands are described. A number of ring sizes and various substituent effects were investigated to enhance the ligand–backbone interactions in the protease active site. Inhibitors <b>5c</b> and <b>5d</b> containing this unprecedented fused 6–5–5 ring system as the P2 ligand, an aminobenzothiazole as the P2′ ligand, and a difluorophenylmethyl as the P1 ligand exhibited exceptional enzyme inhibitory potency and maintained excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The umbrella-like P2 ligand for these inhibitors has been synthesized efficiently in an optically active form using a Pauson–Khand cyclization reaction as the key step. The racemic alcohols were resolved efficiently using a lipase catalyzed enzymatic resolution. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors

Design and Synthesis of Highly Potent HIV‑1 Protease Inhibitors Containing Tricyclic Fused Ring Systems as Novel P2 Ligands: Structure–Activity Studies, Biological and X‑ray Structural Analysis

The design, synthesis, and biological evaluation of a new class of HIV-1 protease inhibitors containing stereochemically defined fused tricyclic polyethers as the P2 ligands and a variety of sulfonamide derivatives as the P2′ ligands are described. A number of ring sizes and various substituent effects were investigated to enhance the ligand–backbone interactions in the protease active site. Inhibitors <b>5c</b> and <b>5d</b> containing this unprecedented fused 6–5–5 ring system as the P2 ligand, an aminobenzothiazole as the P2′ ligand, and a difluorophenylmethyl as the P1 ligand exhibited exceptional enzyme inhibitory potency and maintained excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The umbrella-like P2 ligand for these inhibitors has been synthesized efficiently in an optically active form using a Pauson–Khand cyclization reaction as the key step. The racemic alcohols were resolved efficiently using a lipase catalyzed enzymatic resolution. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors

Design and Development of Highly Potent HIV‑1 Protease Inhibitors with a Crown-Like Oxotricyclic Core as the P2-Ligand To Combat Multidrug-Resistant HIV Variants

Design, synthesis, and evaluation of a new class of exceptionally potent HIV-1 protease inhibitors are reported. Inhibitor <b>5</b> displayed superior antiviral activity and drug-resistance profiles. In fact, this inhibitor showed several orders of magnitude improved antiviral activity over the FDA approved drug darunavir. This inhibitor incorporates an unprecedented 6–5–5 ring-fused crown-like tetrahydro­pyranofuran as the P2 ligand and an aminobenzo­thiazole as the P2′ ligand with the (<i>R</i>)-hydroxyethyl­sulfonamide isostere. The crown-like P2 ligand for this inhibitor has been synthesized efficiently in an optically active form using a chiral Diels–Alder catalyst providing a key intermediate in high enantiomeric purity. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors