Discovery of 2-(6-{[(6-fluoroquinolin-2-yl)methyl]amino}bicyclo[3.1.0]hex-3-yl)-N-hydroxypyrimidine-5-carboxamide (CHR-3996), a class I selective orally active histone deacetylase inhibitor

A novel series of HDAC inhibitors demonstrating class I subtype selectivity and good oral bioavailability is described. The compounds are potent enzyme inhibitors (IC?? values less than 100 nM), and improved activity in cell proliferation assays was achieved by modulation of polar surface area (PSA) through the introduction of novel linking groups. Employing oral pharmacokinetic studies in mice, comparing drug levels in spleen to plasma, we selected compounds that were tested for efficacy in human tumor xenograft studies based on their potential to distribute into tumor. One compound, 21r (CHR-3996), showed good oral activity in these models, including dose-related activity in a LoVo xenograft. In addition 21r showed good activity in combination with other anticancer agents in in vitro studies. On the basis of these results, 21r was nominated for clinical development.     

Synthesis,SAR, and biological evaluation of oximino-piperidino-piperidine amides. 1. Orally bioavailable CCR5 receptor antagonists with potent anti-HIV activity

We previously reported the discovery of 4-[(Z)-(4-bromophenyl)(ethoxyimino)methyl]-1'-[(2,4-dimethyl-3-pyridinyl)carbonyl]-4'-methyl-1,4'-bipiperidine N-oxide 1 (SCH 351125) as an orally bioavailable human CCR5 antagonist for the treatment of HIV-1 infection. Herein, we describe in detail the discovery of 1 from our initial lead compound as well as the synthesis and SAR studies directed toward optimization of substitution at the phenyl, oxime, and right-hand side amide groups in the oximino-piperidino-piperidine series. Substitutions (4-Br, 4-CF(3), 4-OCF(3), 4-SO(2)Me, and 4-Cl) at the phenyl group are well-tolerated, and small alkyl substitutions (Me, Et, (n)()Pr, (i)()Pr, and cyclopropyl methyl) at the oxime moiety are preferred for CCR5 antagonism. The 2,6-dimethylnicotinamide N-oxide moiety is the optimal choice for the right-hand side. Several compounds in this series, including compound 1, exhibited excellent antiviral activity in vitro. Compound 1, which has a favorable pharmacokinetic profile in rodents and primates, excellent oral bioavailability, and potent antiviral activity against a wide range of primary HIV-1 isolates, is a potentially promising new candidate for treatment of HIV-1 infection.     

Synthesis and antiviral evaluation of 6-(trifluoromethylbenzyl) and 6-(fluorobenzyl) analogues of HIV drugs emivirine and GCA-186

The present study describes the synthesis and antiviral evaluation of a series of novel 6-(3-trifluoromethylbenzyl) and 6-(fluorobenzyl) analogues of the HIV drugs emivirine and GCA-186. The objective was to investigate whether the fluoro or trifluoromethyl substituents could lead to an improved antiviral activity against HIV-1 wild type and mutants resistant to non-nucleoside RT inhibitors. The biological test results showed that the most of theses compounds showed good activity against wild type HIV-1. Among them, compound 1-(ethoxymethyl)-6-(3-fluorobenzyl)-5-isopropyluracil (9i) showed the largest inhibitory potency (EC(50) = 0.02 microM), resulting equally potent than emivirine against wild type HIV-1. Furthermore, compound 9i showed marginal better activity against resistant mutants than emivirine. The key steps in the synthesis of the target compounds were either reaction of an appropriate beta-keto ester with thiourea or a cross-coupling reaction of 6-chloro-2,4-dimethoxypyrimidines with benzylic Grignard reagents.     

Discovery of 4-[(Z)-(4-bromophenyl)- (ethoxyimino)methyl]-1'-[(2,4-dimethyl-3- pyridinyl)carbonyl]-4'-methyl-1,4'- bipiperidine N-oxide (SCH 351125): an orally bioavailable human CCR5 antagonist for the treatment of HIV infection

Structure-activity studies on piperidino-piperidine 3 led to the discovery of SCH 351125 (1), a selective CCR5 antagonist with potent activity against RANTES binding (K(i) = 2 nM), which possesses subnanomolar activity in blocking viral entry and has excellent antiviral potency versus a panel of primary HIV-1 viral isolates. Compound 1, which has good oral bioavailability in rats, dogs, and monkeys, is proposed as a potential therapeutic agent for the treatment of HIV-1 and has entered human clinical trials.     

Design,synthesis and activity evaluation of novel pyridinone derivatives as anti-HIV-1 dual (RT/IN) inhibitors

Three series of novel anti-immunodeficiency virus 1 (HIV-1) dual (RT/IN) inhibitors were rationally designed by introducing a functioning diketo acid (DKA) into pyridin-2-one scaffold. To efficiently analyze inhibitory activity, these compounds were screened against HIV-1 RT and IN respectively via surface plasmon resonance (SPR), and active compounds were subsequently evaluated by enzyme assay. It was noteworthy that compound A2 exhibited moderate activity against both HIV-1 RT and IN. This result provided information for further development of pyridinone analogues as potent dual HIV-1 inhibitors.     

5,6-Dihydropyran-2-ones possessing various sulfonyl functionalities: potent nonpeptidic inhibitors of HIV protease

On the basis of previous SAR findings and molecular modeling studies, a series of compounds were synthesized which possessed various sulfonyl moieties substituted at the 4-position of the C-3 phenyl ring substituent of the dihydropyran-2-one ring system. The sulfonyl substituents were added in an attempt to fill the additional S(3)' pocket and thereby produce increasingly potent inhibitors of the target enzyme. Racemic and enantiomerically resolved varieties of selected compounds were synthesized. All analogues in the study displayed decent binding affinity to HIV protease, and several compounds were shown to possess very good antiviral efficacy and safety margins. X-ray crystallographic structures confirmed that the sulfonamide and sulfonate moieties were filling the S(3)' pocket of the enzyme. However, the additional substituent did not provide improved enzymatic inhibitory or antiviral activity as compared to the resolved unsubstituted aniline. The addition of the sulfonyl moiety substitution does not appear to provide favorable pharamacokinectic parameters. Selected inhibitors were tested for antiviral activity in clinical isolates and exhibited similar antiviral activity against all of the HIV-1 strains tested as they did against the wild-type HIV-1. In addition, the inhibitors exhibited good antiviral efficacies against HIV-1 strains that displayed resistance to the currently marketed protease inhibitors.     

Identification, Synthesis, and Biological Evaluation of 6-[(6R)-2-(4-Fluorophenyl)-6-(hydroxymethyl)-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrimidin-3-yl]-2-(2-methylphenyl)pyridazin-3(2H)-one (AS1940477), a Potent p38 MAP Kinase Inhibitor

Several p38 MAPK inhibitors have been shown to effectively block the production of cytokines such as IL-1β, TNFα, and IL-6. Inhibitors of p38 MAP kinase therefore have significant therapeutic potential for the treatment of autoimmune disease. Compound 2a was identified as a potent TNFα production inhibitor in vitro but suffered from poor oral bioavailability. Structural modification of 2a led to the discovery of tetrahydropyrazolopyrimidine derivatives, exemplified by compound 3, with an improved pharmacokinetic profile. We found that blocking metabolism at the methyl group of the amine and constructing the tetrahydropyrimidine core were important to obtaining compounds with good biological profiles and oral bioavailability. Pursuing the structure-activity relationships of this series led to the discovery of AS1940477 (3f), with excellent cellular activity and a favorable pharmacokinetic profile. This compound represents a highly potent inhibitor of p38 MAP kinase with regard to in vivo activity in an adjuvant-induced arthritis model.