Solid-phase synthesis of the alkenyldiarylmethane (ADAM) series of non-nucleoside HIV-1 reverse transcriptase inhibitors

Oxazolidinone-promoted, torquoselective Nazarov cyclizations

Oxazolidinones are powerful promoters of the Nazarov reaction, enabling the cyclization of conventionally resistant substrates to be achieved under mild conditions. They exert excellent regio- and torquoselective control in both the conventional Nazarov reaction giving cyclopentenones and in the "interrupted" Nazarov reaction, giving more highly substituted multistereocenter containing products.

The next ten stories on antiviral drug discovery (part E): advents, advances, and adventures

This review article presents the fifth part (part E) in the series of stories on antiviral drug discovery. The ten stories belonging to this fifth part are dealing with (i) aurintricarboxylic acid; (ii) alkenyldiarylmethanes; (iii) human immunodeficiency virus (HIV) integrase inhibitors; (iv) lens epithelium‐derived growth factor as a potential target for HIV proviral DNA integration; (v) the status presens of neuraminidase inhibitors NAIs in the control of influenza virus infections; (vi) the status presens on respiratory syncytial virus inhibitors; (vii) tricyclic (1,N‐2‐ethenoguanine)‐based acyclovir and ganciclovir derivatives; (viii) glycopeptide antibiotics as antivirals targeted at viral entry; (ix) the potential (off‐label) use of cidofovir in the treatment of polyoma (JC and BK) virus infections; and (x) finally, thymidine phosphorylase as a target for both antiviral and anticancer agents. © 2009 Wiley Periodicals, Inc. Med Res Rev, 31, No. 1, 118–160, 2010

Crystallographic study of a novel subnanomolar inhibitor provides insight on the binding interactions of alkenyldiarylmethanes with human immunodeficiency virus-1 reverse transcriptase

Two crystal structures have been solved for separate complexes of alkenyldiarylmethane (ADAM) nonnucleoside reverse transcriptase inhibitors (NNRTI) 3 and 4 with HIV-1 reverse transcriptase (RT). The structures reveal inhibitor binding is exclusively hydrophobic in nature and the shape of the inhibitor-bound NNRTI binding pocket is unique among other reported inhibitor-RT crystal structures. Primarily, ADAMs 3 and 4 protrude from a large gap in the back side of the binding pocket, placing portions of the inhibitors unusually close to the polymerase active site and allowing 3 to form a weak hydrogen bond with Lys223. The lack of additional stabilizing interactions, beyond the observed hydrophobic surface contacts, between 4 and RT is quite perplexing given the extreme potency of the compound (IC(50) Collapse

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MESH Headings

• Animals
• Crystallography, X-Ray
• HIV Reverse Transcriptase/antagonists & inhibitors
• HIV Reverse Transcriptase/chemistry
• HIV Reverse Transcriptase/metabolism
• HIV-1/drug effects
• HIV-1/enzymology
• Humans
• Hydrolysis
• Inhibitory Concentration 50
• Methane/blood
• Methane/chemistry
• Methane/metabolism
• Methane/pharmacology
• Models, Molecular
• Protein Binding
• Protein Structure, Tertiary
• Rats
• Reverse Transcriptase Inhibitors/blood
• Reverse Transcriptase Inhibitors/chemistry
• Reverse Transcriptase Inhibitors/metabolism
• Reverse Transcriptase Inhibitors/pharmacology

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Grants

• F32GM084726 NIGMS NIH HHS
• R01 AI043637-04A2 NIAID NIH HHS
• R01 AI043637-06 NIAID NIH HHS
• R01 AI027690 NIAID NIH HHS
• R01-AI-43637 NIAID NIH HHS
• R01 AI043637-05 NIAID NIH HHS
• R01 AI043637 NIAID NIH HHS
• AI 27690 NIAID NIH HHS
• R37 AI027690 NIAID NIH HHS
• F32 GM084726 NIGMS NIH HHS
• C06-14499 PHS HHS

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Affiliation(s)

Matthew D. Cullen Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, and the Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907, USA
William C. Ho Department of Chemistry and Chemical Biology, Center for Advanced Biotechnology and Medicine, Rutgers University, 679 Hoes Lane West, Pistcataway, NJ 08854, USA
Joseph D. Bauman Department of Chemistry and Chemical Biology, Center for Advanced Biotechnology and Medicine, Rutgers University, 679 Hoes Lane West, Pistcataway, NJ 08854, USA
Kalyan Das Department of Chemistry and Chemical Biology, Center for Advanced Biotechnology and Medicine, Rutgers University, 679 Hoes Lane West, Pistcataway, NJ 08854, USA
Eddy Arnold Department of Chemistry and Chemical Biology, Center for Advanced Biotechnology and Medicine, Rutgers University, 679 Hoes Lane West, Pistcataway, NJ 08854, USA
Tracy L. Hartman ImQuest Biosciences, Inc., 7340 Executive Way, Suite R, Frederick, Maryland 21704, USA
Karen M. Watson ImQuest Biosciences, Inc., 7340 Executive Way, Suite R, Frederick, Maryland 21704, USA
Robert W. Buckheit ImQuest Biosciences, Inc., 7340 Executive Way, Suite R, Frederick, Maryland 21704, USA
Christophe Pannecouque Rega Institute for Medical Research, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
Erik De Clercq Rega Institute for Medical Research, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
Mark Cushman Department of Medicinal Chemistry and Molecular Pharmacology, School of Pharmacy and Pharmaceutical Sciences, and the Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907, USA

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Synthesis of alkenyldiarylmethanes (ADAMs) containing benzo[d]isoxazole and oxazolidin-2-one rings, a new series of potent non-nucleoside HIV-1 reverse transcriptase inhibitors

As a continuation of efforts to replace the metabolically labile methyl esters of lead alkenyldiarylmethanes (ADAMs) with stable bioisosteres, compounds bearing benzo[d]isoxazole and oxazolidine-2-one rings were designed and evaluated as a new series of potent HIV-1 non-nucleoside reverse transcriptase inhibitors with anti-HIV activity. All of the resulting ADAMs were found to inhibit HIV-1 RT with poly(rC) x oligo(dG) as the template primer. The most promising compound in this series was ADAM 3, with EC(50) values of 40 nM (vs HIV-1(RF)) and 20 nM (vs HIV-1(IIIB)). Compound 3 also inhibited HIV-1 reverse transcriptase with an IC(50) of 0.91 microM. ADAM 4 has an antiviral EC(50) of 0.6 microM in CEM-SS cells and a plasma half-life of 51.4 min.

Investigation of the alkenyldiarylmethane non-nucleoside reverse transcriptase inhibitors as potential cAMP phosphodiesterase-4B2 inhibitors

The alkenyldiarylmethanes (ADAMs) are currently being investigated as non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs) of potential value in the treatment of HIV infection and AIDS. During the course of these studies, a number of ADAM analogues have been identified that protect HIV-infected cells from the cytopathic effects of the virus by an unknown, HIV-1 RT-independent mechanism. Since the phosphodiesterase 4 family is required for HIV infection, the effect of various ADAMs on the activity of PDE4B2 was investigated in an effort to determine if the ADAMs could possibly be targeting phosphodiesterases. Six compounds representative of the ADAM class were tested for inhibition of cAMP hydrolysis by PDE4B2 enzymatic activity. Four ADAMs were found to be weak inhibitors of PDE4B2 and two of them were inactive. The experimental results are consistent with an antiviral mechanism that does not include inhibition of PDE4 isoforms.

Synthesis and anti-HIV activity of new metabolically stable alkenyldiarylmethane non-nucleoside reverse transcriptase inhibitors incorporating N-methoxy imidoyl halide and 1,2,4-oxadiazole systems

The alkenyldiarylmethanes (ADAMs) are a unique class of non-nucleoside reverse transcriptase inhibitors (NNRTIs) that are capable of inhibiting HIV-1 reverse transcriptase (RT) through an allosteric mechanism. However, the potential usefulness of the ADAMs is limited by the presence of metabolically labile methyl ester moieties that are hydrolyzed by nonspecific esterases present in blood plasma, resulting in the formation of the inactive carboxylic acid metabolites. Therefore, to discover metabolically stable ADAMs, the design and synthesis of a new class of ADAMs with N-methoxy imidoyl halide and 1,2,4-oxadiazole systems were attempted. The resulting new ADAM 6 displayed enhanced metabolic stability in rat plasma (t1/2 = 61 h) along with the ability to inhibit HIV-1 reverse transcriptase and the cytopathic effect of HIV-1RF and HIV-1IIIB at submicromolar concentrations.

Synthesis and anti-HIV activity of new alkenyldiarylmethane (ADAM) non-nucleoside reverse transcriptase inhibitors (NNRTIs) incorporating benzoxazolone and benzisoxazole rings

The HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) constitute a large and structurally diverse set of compounds, several of which are currently used in the treatment of AIDS. A series of novel alkenyldiarylmethanes (ADAMs) were designed and synthesized as part of an ongoing investigation to replace the metabolically labile methyl ester moieties found in the ADAM pharmacophore with stable modifications that retain the potent anti-HIV activity of the parent compounds. Unsurprisingly, the rat plasma half-lives of the new ADAMs were not improved when compared to the parent compounds, but all of the synthesized ADAMs inhibited the cytopathic effect of HIV-1 in cell culture. The most potent compound identified was (E)-5-[1-(3,7-dimethyl-2-oxo-2,3-dihydro-benzoxazol-5-yl)-5-methoxycarbonyl-pent-1-enyl]-2-methoxy-3-methylbenzoic acid methyl ester (7), which inhibited the cytopathic effects of both HIV-1(RF) and HIV-1(IIIB) strains in cell cultures with EC50 values of 30 and 90 nM, respectively, and inhibited HIV-1 reverse transcriptase with an IC50 of 20 nM.

Synthesis, anti-HIV activity, and metabolic stability of new alkenyldiarylmethane HIV-1 non-nucleoside reverse transcriptase inhibitors

Non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTIs) are part of the combination therapy currently used to treat HIV infection. Based on analogy with known HIV-1 NNRT inhibitors, 18 novel alkenyldiarylmethanes (ADAMs) containing 5-chloro-2-methoxyphenyl, 3-cyanophenyl, or 3-fluoro-5-trifluoromethylphenyl groups were synthesized and evaluated as HIV inhibitors. Their stabilities in rat plasma have also been investigated. Although introducing 5-chloro-2-methoxyphenyl or 3-fluoro-5-trifluoromethylphenyl groups into alkenyldiarylmethanes does not maintain the antiviral potency, the structural modification of alkenyldiarylmethanes with a 3-cyanophenyl substituent can be made without a large decrease in activity. The oxazolidinonyl group was introduced into the alkenyldiarylmethane framework and found to confer enhanced metabolic stability in rat plasma.

Synthesis of alkenyldiarylmethane (ADAM) non-nucleoside HIV-1 reverse transcriptase inhibitors with non-identical aromatic rings

The existing methods for the synthesis of alkenyldiarylmethane (ADAM) non-nucleoside reverse transcriptase inhibitors proceed from symmetrical benzophenones and therefore result in products with identical aromatic rings. New methods have therefore been devised for the preparation of stereochemically defined ADAMs with non-identical aromatic rings. The new routes rely on palladium-catalyzed reactions, including Sonogashira, Suzuki, Stille, and hydroarylation methodology. Several of the new ADAMs inhibited the cytopathic effect of HIV-1 in cell culture and HIV-1 reverse transcriptase at submicromolar concentrations.