Design of a novel pyrrolidine scaffold utilized in the discovery of potent and selective human ß3 adrenergic receptor agonists.

A novel class of human ß(3)-adrenergic receptor agonists was designed in effort to improve selectivity and metabolic stability versus previous disclosed ß(3)-AR agonists. As observed, many of the ß(3)-AR agonists seem to need the acyclic ethanolamine core for agonist activity. We have synthesized derivatives that constrained this moiety by introduction of a pyrrolidine. This unique modification maintains human ß(3) functional potency with improved selectivity versus ancillary targets and also eliminates the possibility of the same oxidative metabolites formed from cleavage of the N-C bond of the ethanolamine. Compound 39 exhibited excellent functional ß(3) agonist potency across species with good pharmacokinetic properties in rat, dog, and rhesus monkeys. Early de-risking of this novel pyrrolidine core (44) via full AMES study supports further research into various new ß(3)-AR agonists containing the pyrrolidine moiety.

Discovery of potent, selective, and orally bioavailable 3H-spiro[isobenzofuran-1,4'-piperidine] based melanocortin subtype-4 receptor agonists.

Design, synthesis, and SAR of a series of 3H-spiro[isobenzofuran-1,4'-piperidine] based compounds as potent, selective and orally bioavailable melanocortin subtype-4 receptor (MC4R) agonists are disclosed.

Discovery of a spiroindane based compound as a potent, selective, orally bioavailable melanocortin subtype-4 receptor agonist.

We report the design, synthesis and properties of spiroindane based compound 1, a potent, selective, orally bioavailable, non-peptide melanocortin subtype-4 receptor agonist. Compound 1 shows excellent erectogenic activity in the rodent models.

1-Sulfonyl-4-acylpiperazines as selective cannabinoid-1 receptor (CB1R) inverse agonists for the treatment of obesity.

A novel series of 1-sulfonyl-4-acylpiperazines as selective cannabinoid-1 receptor (CB1R) inverse agonists was discovered through high throughput screening (HTS) and medicinal chemistry lead optimization. Potency and in vivo properties were systematically optimized to afford orally bioavailable, highly efficacious, and selective CB1R inverse agonists that caused food intake suppression and body weight reduction in diet-induced obese rats and dogs. It was found that the receptor binding assay predicted in vivo efficacy better than functional antagonist/inverse agonist activities. This observation expedited the structure-activity relationship (SAR) analysis and may have implications beyond the series of compounds presented herein.

Diastereoselective Friedel-Crafts alkylation of indoles with chiral alpha-phenyl benzylic cations. Asymmetric synthesis of anti-1,1,2-triarylalkanes.

The reactions of chiral benzyl carbocations bearing alpha-phenyl substituents with N-sulfonylated indoles afford 1,1,2-triarylalkanes with anti-selectivities. This outcome is a reversal of facial diastereoselectivity relative to Bach's alpha-alkyl-bearing benzyl cations. The reactions are promoted by either a Brønsted acid (TFA) or Lewis acid (BF3.OEt2), offering differential diastereoselectivities and reactivities. The electronic properties of both reacting partners strongly influence the reaction rates and the product diastereoselectivities and appear to operate under kinetic control. This chemistry provides an efficient access to sterically congested tetrasubstituted ethanes.

Conformational analysis and receptor docking of N-[(1S,2S)-3-(4-chlorophenyl)-2-(3-cyanophenyl)-1-methylpropyl]-2-methyl-2-{[5-(trifluoromethyl)pyridin-2-yl]oxy}propanamide (taranabant, MK-0364), a novel, acyclic cannabinoid-1 receptor inverse agonist.

X-ray crystallographic, NMR spectroscopic, and computational studies of taranabant afforded similar low-energy conformers with a significant degree of rigidity along the C11-N13-C14-C16-C17 backbone but with more flexibility around bonds C8-C11 and C8-O7. Mutagenesis and docking studies suggested that taranabant and rimonabant shared the same general binding area of CB1R but with significant differences in detailed interactions. Similar to rimonabant, taranabant interacted with a cluster of aromatic residues (F(3.36)200, W(5.43)279, W(6.48)356, and Y(5.39)275) through the two phenyl rings and with F(2.57)170 and L(7.42)387 through the CF 3-Pyr ring. The notable distinction between taranabant and rimonabant was that taranabant was hydrogen-bonded with S(7.39)383 but not with K(3.28)192, while rimonabant was hydrogen-bonded with K(3.28)192 but not with S(7.39)383. The strong hydrogen bonding between the amide NH of taranabant and hydroxyl of S(7.39)383 was key to the superior affinity of taranabant to CB1R.

Conformational studies of 3-amino-1-alkyl-cyclopentane carboxamide CCR2 antagonists leading to new spirocyclic antagonists.

In an effort to shed light on the active binding conformation of our 3-amino-1-alkyl-cyclopentane carboxamide CCR2 antagonists, we prepared several conformationally constrained analogs resulting from backbone cyclization. Evaluation of CCR2 binding affinities for these analogs gave insight into the optimal relative positions of the piperidine and benzylamide moieties while simultaneously leading to the discovery of a new, potent lead type based upon a spirocyclic acetal scaffold.

The discovery of potent, selective, and orally bioavailable hNK1 antagonists derived from pyrrolidine.

SAR studies on amides, ureas, and vinylogous amides derived from pyrrolidine led to the discovery of several potent hNK(1) antagonists. One particular vinylogous amide (45b) had excellent potency, selectivity, pharmacokinetic profile, and functional activity in vivo. An in vivo rhesus macaque brain receptor occupancy PET study for compound 45b revealed an estimated Occ(90) approximately 300 ng/ml.

A potent and orally active HIV-1 integrase inhibitor.

A 1,6-naphthyridine inhibitor of HIV-1 integrase has been discovered with excellent inhibitory activity in cells, good pharmacokinetics, and an excellent ability to inhibit virus with mutant enzyme.

Isolation, structure, and absolute stereochemistry of platensimycin, a broad spectrum antibiotic discovered using an antisense differential sensitivity strategy.

Fatty acids are essential for survival of bacteria and are synthesized by a series of enzymes including the elongation enzymes, beta-ketoacyl acyl carrier protein synthase I/II (FabF/B). Inhibition of fatty acid synthesis is one of the new targets for the discovery and development of antibacterial agents. Platensimycin (1a) is a novel broad spectrum Gram-positive antibiotic produced by Streptomyces platensis. It was discovered by target-based whole-cell screening strategy using antisense differential sensitivity assay. It inhibits bacterial growth by selectively inhibiting condensing enzyme FabF of the fatty acid synthesis pathway and was isolated by a two-step process, a capture step followed by reversed-phase HPLC. The structure was elucidated by 2D NMR methods and confirmed by X-ray crystallographic analysis of a bromo derivative. It was determined that potential reactivity of the enone moiety does not play a key role in the biological activity of platensimycin. However, cyclohexenone ring conformation renders for the stronger binding interaction with the enzyme. The isolation, structure elucidation, derivatization, and biological activity of 6,7-dihydroplatensimycin are described.

Cyclopentane-based human NK1 antagonists. Part 2: development of potent, orally active, water-soluble derivatives.

The synthesis and optimization of a cyclopentane-based hNK1 antagonist scaffold 3, having four chiral centers, will be discussed in the context of its enhanced water solubility properties relative to the marketed anti-emetic hNK1 antagonist EMEND (Aprepitant). Sub-nanomolar hNK1 binding was achieved and oral activity comparable to Aprepitant in two in vivo models will be described.

Preparation of 2,5,7-trithiabicyclo[2.2.1]heptane from 1,2-bis-triisopropylsilanylsulfanyl alkenes.

[reaction: see text] The chemical behavior of 1,2-bis-triisopropylsilanylsulfanyl alkenes 1 is relatively unexplored, and the weak sulfur-silicon bonds give rise to various transformations. Under acidic conditions (HCl) and in the presence of a Lewis acid at room temperature the bicyclic adduct 2 is obtained in good yield. The structure was confirmed by X-ray crystal analysis with R = benzyl.

A series of 5-(5,6)-dihydrouracil substituted 8-hydroxy-[1,6]naphthyridine-7-carboxylic acid 4-fluorobenzylamide inhibitors of HIV-1 integrase and viral replication in cells.

Introduction of a 5,6-dihydrouracil functionality in the 5-position of N-(4-fluorobenzyl)-8-hydroxy-[1,6]naphthyridine-7-carboxamide 1 led to a series of highly active HIV-1 integrase inhibitors. These compounds displayed low nanomolar activity in inhibiting both the strand transfer process of HIV-1 integrase and viral replication in cells. Compound 11 is a 150-fold more potent antiviral agent than 1, with a CIC(95) of 40 nM in the presence of human serum. It displays good pharmacokinetics when dosed in rats and dogs.

Aryl sulfones: a new class of gamma-secretase inhibitors.

The development of a novel series of 4-aryl, 4-phenylsulfonyl cyclohexananone-derived gamma-secretase inhibitors for the potential treatment of Alzheimer's disease is described.

Dual protein farnesyltransferase-geranylgeranyltransferase-I inhibitors as potential cancer chemotherapeutic agents.

A series of novel diaryl ether lactams have been identified as very potent dual inhibitors of protein farnesyltransferase (FTase) and protein geranylgeranyltransferase I (GGTase-I), enzymes involved in the prenylation of Ras. The structure of the complex formed between one of these compounds and FTase has been determined by X-ray crystallography. These compounds are the first reported to inhibit the prenylation of the important oncogene Ki-Ras4B in vivo. Unfortunately, doses sufficient to achieve this endpoint were rapidly lethal.

Optimization of a tertiary alcohol series of phosphodiesterase-4 (PDE4) inhibitors: structure-activity relationship related to PDE4 inhibition and human ether-a-go-go related gene potassium channel binding affinity.

A SAR study on the tertiary alcohol series of phosphodiesterase-4 (PDE4) inhibitors related to 1 is described. In addition to inhibitory potency against PDE4 and the lipopolysaccharide-induced production of TNFalpha in human whole blood, the binding affinity of these compounds for the human ether-a-go-go related gene (hERG) potassium channel (an in vitro measure for the potential to cause QTc prolongation) was assessed. Four key structural moieties in the molecule were studied, and the impact of the resulting modifications in modulating these activities was evaluated. From these studies, (+)-3d (L-869,298) was identified as an optimized structure with respect to PDE4 inhibitory potency, lack of binding affinity to the hERG potassium channel, and pharmacokinetic behavior. (+)-3d exhibited good in vivo efficacy in several models of pulmonary function with a wide therapeutic index with respect to emesis and prolongation of the QTc interval.

Benzamide derivatives as blockers of Kv1.3 ion channel.

The voltage-gated potassium channel, Kv1.3, is present in human T-lymphocytes. Blockade of Kv1.3 results in T-cell depolarization, inhibition of T-cell activation, and attenuation of immune responses in vivo. A class of benzamide Kv1.3 channel inhibitors has been identified. The structure-activity relationship within this class of compounds in two functional assays, Rb_Kv and T-cell proliferation, is presented. In in vitro assays, trans isomers display moderate selectivity for binding to Kv1.3 over other Kv1.x channels present in human brain.

Efficient synthesis of NK(1) receptor antagonist aprepitant using a crystallization-induced diastereoselective transformation.

An efficient stereoselective synthesis of the orally active NK(1) receptor antagonist Aprepitant is described. A direct condensation of N-benzyl ethanolamine with glyoxylic acid yielded a 2-hydroxy-1,4-oxazin-3-one which was activated as the corresponding trifluoroacetate. A Lewis acid mediated coupling with enantiopure (R)-1-(3,5-bis(trifluoromethyl)phenyl)ethan-1-ol afforded a 1:1 mixture of acetal diastereomers which was converted into a single isomer via a novel crystallization-induced asymmetric transformation. The resulting 1,4-oxazin-3-one was converted via a unique and highly stereoselective one-pot process to the desired alpha-(fluorophenyl)morpholine derivative. Interesting and unexpected [1,2]-Wittig and [1,3]-sigmatropic rearrangements were identified during the optimization of these key steps. In the final step, a triazolinone side chain was appended to the morpholine core. The targeted clinical candidate was thus obtained in 55% overall yield over the longest linear sequence.

Asymmetric synthesis of alpha,alpha-difluoro-beta-amino acid derivatives from enantiomerically pure N-tert-butylsulfinimines.

Addition of the Reformatsky reagent derived from ethyl bromodifluoroacetate to alkyl- and aryl-substituted N-tert-butylsulfinimines furnishes beta-tert-butylsulfinamyl-beta-substituted alpha,alpha-difluoroproponiates in diastereomeric ratios ranging from 80:20 to 95:5. The diastereomers are easily separated and the enantiomerically pure, protected beta-amino esters are readily transformed to the corresponding acid, amide, and amine derivatives as useful synthons for medicinal chemistry targets.