Discovery of a Hepatitis C Virus NS5B Replicase Palm Site Allosteric Inhibitor (BMS-929075) Advanced to Phase 1 Clinical Studies

The hepatitis C virus (HCV) NS5B replicase is a prime target for the development of direct-acting antiviral drugs for the treatment of chronic HCV infection. Inspired by the overlay of bound structures of three structurally distinct NS5B palm site allosteric inhibitors, the high-throughput screening hit anthranilic acid 4, the known benzofuran analogue 5, and the benzothiadiazine derivative 6, an optimization process utilizing the simple benzofuran template 7 as a starting point for a fragment growing approach was pursued. A delicate balance of molecular properties achieved via disciplined lipophilicity changes was essential to achieve both high affinity binding and a stringent targeted absorption, distribution, metabolism, and excretion profile. These efforts led to the discovery of BMS-929075 (37), which maintained ligand efficiency relative to early leads, demonstrated efficacy in a triple combination regimen in HCV replicon cells, and exhibited consistently high oral bioavailability and pharmacokinetic parameters across preclinical animal species. The human PK properties from the Phase I clinical studies of 37 were better than anticipated and suggest promising potential for QD administration.

Selective IKur Inhibitors for the Potential Treatment of Atrial Fibrillation: Optimization of the Phenyl Quinazoline Series Leading to Clinical Candidate 5-[5-Phenyl-4-(pyridin-2-ylmethylamino)quinazolin-2-yl]pyridine-3-sulfonamide

We have recently disclosed 5-phenyl-N-(pyridin-2-ylmethyl)-2-(pyrimidin-5-yl)quinazolin-4-amine 1 as a potent I_Kur current blocker with selectivity versus hERG, Na and Ca channels, and an acceptable preclinical PK profile. Upon further characterization in vivo, compound 1 demonstrated an unacceptable level of brain penetration. In an effort to reduce the level of brain penetration while maintaining the overall profile, SAR was developed at the C2' position for a series of close analogues by employing hydrogen bond donors. As a result, 5-[5-phenyl-4-(pyridin-2-ylmethylamino)quinazolin-2-yl]pyridine-3-sulfonamide (25) was identified as the lead compound in this series. Compound 25 showed robust effects in rabbit and canine pharmacodynamic models and an acceptable cross-species pharmacokinetic profile and was advanced as the clinical candidate. Further optimization of 25 to mitigate pH-dependent absorption resulted in identification of the corresponding phosphoramide prodrug (29) with an improved solubility and pharmacokinetic profile.

Discovery of 5-Phenyl-N-(pyridin-2-ylmethyl)-2-(pyrimidin-5-yl)quinazolin-4-amine as a Potent I Kur Inhibitor

A new series of phenylquinazoline inhibitors of Kv 1.5 is disclosed. The series was optimized for Kv 1.5 potency, selectivity versus hERG, pharmacokinetic exposure, and pharmacodynamic potency. 5-Phenyl-N-(pyridin-2-ylmethyl)-2-(pyrimidin-5-yl)quinazolin-4-amine (13k) was identified as a potent and ion channel selective inhibitor with robust efficacy in the preclinical rat ventricular effective refractory period (VERP) model and the rabbit atrial effective refractory period (AERP) model.

Regioselective Synthesis of Substituted 4-Alkylamino and 4-Arylaminophthalazin-1(2H)-ones

An efficient regioselective synthesis of substituted 4-alkylamino and 4-arylaminophthalazin-1(1H)-ones 5 is described. This new method features the formation of substituted phthalazin-1(1H)-ones 3 by the reaction of 2-formylbenzoic acids 1 or 3-hydroxyisobenzofuran-1(3H)-ones 2 with hydrazine to generate phthalazin-1(2H)-ones 3. Subsequent regioselective bromination of phthalazin-1(2H)-ones 3 with benzyltrimethylammonium tribromide (BTMA-Br3) followed by mixed copper-copper oxide-catalyzed amination of 4-bromophthalazin-1(2H)-ones 4 with primary amines generates aminophthalazin-1(2H)-ones in good overall yields.

Design, synthesis, and anti-tumor activity of 4'-thionucleosides as potent and selective agonists at the human A3 adenosine receptor

On the basis of potent and selective binding affinity of Cl-IB-MECA to the human A(3) adenosine receptor, its 4'-thioadenosine derivatives were efficiently synthesized starting from D-gulonic gamma-lactone. Among compounds tested, 2-chloro-N(6)-(3-iodobenzyl)- and 2-chloro-N(6)-methyl-4' -thioadenosine-5' -methyluronamides (7a and 7b) exhibited nanomolar range of binding affinity (K(i) = 0.38 nM and 0.28 nM, respectively) at the human A(3)AR. These compounds showed anti-growth effects on HL-60 leukemia cell, which resulted from the inhibition of Wnt signaling pathway.

Stereoselective synthesis of 1'-functionalized-4'-thionucleosides

Stereoselective functionalization of the 1'-position of 4'-thionucleosides was achieved using a stereoselective S(N)2 reaction controlled by 5-membered ring coordination.

Stereoselective functionalization of the 1'-position of 4'-thionucleosides

Stereoselective synthesis of novel 1'-alpha-substituted-4'-thionucleosides was achieved starting from D-gulonic acid gamma-lactone via stereoselective nucleophilic substitution.

Discovery of a new nucleoside template for human A3 adenosine receptor ligands: D-4'-thioadenosine derivatives without 4'-hydroxymethyl group as highly potent and selective antagonists

Truncated D-4'-thioadenosine derivatives lacking the 4'-hydroxymethylene moiety were synthesized starting from D-mannose, using cyclization to the 4-thiosugar and one-step conversion of the diol to the acetate as key steps. At the human A3 adenosine receptor (AR), N6-substituted purine analogues bound potently and selectively and acted as antagonists in a cyclic AMP functional assay. An N6-(3-chlorobenzyl)purine analogue 9b displayed a Ki value of 1.66 nM at the human A3 AR. Thus, truncated D-4'-thioadenosine is an excellent template for the design of novel A3 AR antagonists to act at both human and murine species.

Design, synthesis, and biological activity of N6-substituted-4'-thioadenosines at the human A3 adenosine receptor

A large series of N6-substituted-4'-thioadenosines were synthesized starting from D-gulonic-gamma-lactone, and structure-activity relationships were studied at the human A3 and other subtypes of adenosine receptors (ARs). 2-Chloro-substituted and 2-H analogues were compared. 2-Chloro-N6-methyl-4'-thioadenosine 19b was a highly potent and selective agonist (Ki=0.8+/-0.1 nM in binding) at the A3AR, and displayed the same relative efficacy in receptor activation as a known full agonist, Cl-IB-MECA. Most of N6-substituted-4'-thioadenosines were less potent in binding than the corresponding N6-substituted-adenosines or N6-substituted-4'-thioadenosine-5'-uronamides. N6-(3-Iodobenzyl) derivative 19g was demonstrated to be an A3AR-selective partial agonist displaying a Ki value of 3.2 nM.

Stereoselective synthesis of novel thioiso dideoxy nucleosides with exocyclic methylene as potential antiviral agents

Novel thioiso pyrimidine and purine nucleosides substituted with exocyclic methylene have been synthesized, starting from D-xylose. Cyclization of the dimesylate to the 4-thiosugar 6a proceeded in pure SN2 reaction in the presence of allylic functional group.

Structure−Activity Relationships of 2-Chloro-N6-substituted-4‘-thioadenosine-5‘-uronamides as Highly Potent and Selective Agonists at the Human A3 Adenosine Receptor

We have established structure-activity relationships of novel 4'-thionucleoside analogues as the A(3) adenosine receptor (AR) agonists. Binding affinity, selectivity toward other AR subtypes, and efficacy in inhibition of adenylate cyclase were studied. From this study, 2-chloro-N(6)-methyl-4'-thioadenosine-5'-methyluronamide (36a) emerged as the most potent and selective agonist at the human A(3) AR. We have also revealed that, similar to 4'-oxoadenosine analogues, at least one hydrogen on the 5'-uronamide moiety was necessary for high-affinity binding at the human A(3) AR, presumably to allow this group to donate a H bond within the binding site. Furthermore, bulky substituents on the 5'-uronamide reduced binding affinity, but in some cases large 5'-uronamide substituents, such as substituted benzyl and 2-phenylethyl groups, maintained moderate affinity with reduced efficacy, leading to A(3) AR partial agonists or antagonists. In several cases for which the corresponding 4'-oxonucleosides have been studied, the 4'-thionucleosides showed higher binding affinity to the A(3) AR.

Asymmetric synthesis of novel thioiso dideoxynucleosides with exocyclic methylene as potential antiviral agents

Novel thioiso pyrimidine and purine nucleosides substituted with exocyclic methylene have been synthesized, starting from D-xylose. The glycosyl donor 14 was synthesized from D-xylose, using cyclization of dimesylate 10 with sodium sulfide as a key step. Cyclization proceeded in pure S(N)2 reaction without going through S(N)1 reaction in the presence of an allylic functional group at low reaction temperature (0 degrees C) in polar solvent (DMF), affording compound 12 as a major product. At higher temperatures, S(N)2' product 11 was almost exclusively obtained as a major product. On the other hand, glycosylation of 14 with 6-chloropurine under Mitsunobu conditions afforded the desired S(N)2 product 26, while palladium-catalyzed glycosylation resulted in the sole formation of S(N)2' product 34.

Synthesis of d - and l -apio nucleoside analogues with 2′-hydroxyl group as potential anti-HIV agents

The present work describes the asymmetric synthesis of D- and L-apio-2',3'-dideoxynucleoside analogues, 4 and 5 with 2'-hydroxyl group via a common intermediate 9, starting from D-galactose. Stereoselective dihydroxylation and deoxygenation through radical inversion were successfully employed to synthesize the key intermediate 12 with D-apio structure, while stereoselecetive hydroboration-oxidation was used for the synthesis of another key intermediate 18 with L-apio structure.

Design and synthesis of A3 adenosine receptor ligands, 2'-fluoro analogues of Cl-IB-MECA

Synthesis of 2'-deoxy-2'-fluoro-N6-substituted adenosines as bioisosteres of Cl-IB-MECA and their binding affinities to A3 adenosine receptor are described.

N6-substituted D-4'-thioadenosine-5'-methyluronamides: potent and selective agonists at the human A3 adenosine receptor

4'-Thio analogues 3-5 of Cl-IB-MECA (2) (K(i) = 1.0 +/- 0.2 nM at the human A(3) adenosine receptor) were synthesized from d-gulono-gamma-lactone via 4-thioribosyl acetate 14 as the key intermediate. All synthesized 4'-thionucleosides exhibited higher binding affinity to the human A(3) adenosine receptor than Cl-IB-MECA, among which 4 showed the most potent binding affinity (K(i) = 0.28 +/- 0.09 nM). 4 was also selective for A(3) vs human A(1) and human A(2A) receptors by 4800- and 36000-fold, respectively.

Synthesis and biological studies of some imidazolinone derivatives

A Series of 4-(1-Aryl-5-oxo-2-phenyl-2-imidazolin-4-yl) metheno-5-chloro-3-methyl-1-phenyl-3-pyrazole) were synthesised and tested for their antibacterial, antiinflammatory and analagesic activities. Some of the compounds showed significant antiinflammatory properties.

Studies on the synthesis and biological activity of 3-(substituted anilinomethyl)-4-(5-substituted-2-furfurylidene)amino-1,2,4 -triazole-5- thiones and their Mannich bases

A series of 3-(substituted anilinomethyl)-4-(5-substituted-2- furfurylidene)amino-1,2,4-triazole-5-thiones were synthesized as potential biologically active agents. They were converted to Mannich bases, by treating with suitable amine in the presence of formaldehyde in alcohol medium. The newly synthesized compounds were screened for their antibacterial and antifungal activities.