Discovery and SAR studies of 2-alkyl-3-phenyl-2,4,5,6,7,8-hexahydropyrazolo[3,4-d]azepines as 5-HT7/2 inhibitors leading to the identification of a clinical candidate.

We report here the synthesis and characterization of a dual 5-HT7 / 5-HT2 receptor antagonist 3-(4-Fluoro-phenyl)-2-isopropyl-2,4,5,6,7,8-hexahydro-1,2,6-triaza-azulene (4j). 4j is a high affinity 5-HT7 and 5-HT2A receptor ligand having a pKi = 8.1 at both receptors. It behaves as an antagonist in an in vitro functional assay for 5-HT2A and as an inverse agonist in an in vitro functional assay for 5-HT7. In a validated in vivo model for central 5-HT7 activity in rats, blockade of 5-carboxamidotryptamine (5-CT) induced hypothermia, 4j shows efficacy at low doses (ED50 = 0.05 mg/kg, p.o., 1 h) and maximal efficacy was observed at 0.3 mg/kg p.o. with a corresponding plasma concentration of ~27 ng/ml. In a validated in vivo model for central 5-HT2A activity, blockade of 2,5-dimethoxy-4-iodoamphetamine (DOI) induced head-twitches in mice, 4j shows efficacy at low doses with an ED50 = 0.3 mg/kg p.o. Ex vivo receptor binding studies demonstrate that 4j occupied 5-HT2A receptor binding sites in the frontal cortex of the rat brain with an ED50 in good agreement with the ED50 value for central functional effect mediated by 5-HT2A receptor (ED50 = 0.8 mg/kg, p.o., 1 h).

Substituted 5,6-(Dihydropyrido[3,4-d]pyrimidin-7(8H)-yl)-methanones as P2X7 Antagonists.

We describe the synthesis of a novel class of brain penetrating P2X7 antagonists with high potency at both the rat and human P2X7 receptors. Disclosed herein are druglike molecules with demonstrated target engagement of the rat P2X7 receptors after an oral dose. Specifically, compound 20 occupied the P2X7 receptors >80% over the 6 h time course as measured by an ex vivo radioligand binding experiment. In a dose-response assay, this molecule has a plasma EC50 of 8 ng/mL. Overall, 20 has suitable druglike properties and pharmacokinetics in rat and dog. This molecule and others disclosed herein will serve as additional tools to elucidate the role of the P2X7 receptor in neuropsychiatric disorders.

Novel methyl substituted 1-(5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanones are P2X7 antagonists.

The optimization efforts that led to a novel series of methyl substituted 1-(5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanones that are potent rat and human P2X7 antagonists are described. These efforts resulted in the discovery of compounds with good drug-like properties that are capable of high P2X7 receptor occupancy in rat following oral administration, including compounds 7n (P2X7 IC50 = 7.7 nM) and 7u (P2X7 IC50 =7 .7 nM). These compounds are expected to be useful tools for characterizing the effects of P2X7 antagonism in models of depression and epilepsy, and several of the compounds prepared are candidates for effective P2X7 PET tracers.

The discovery and synthesis of JNJ 31020028, a small molecule antagonist of the Neuropeptide Y Y2 receptor.

A series of small molecules based on a chemotype identified from our compound collection were synthesized and tested for binding affinity (IC(50)) at the human Neuropeptide Y Y(2) receptor (NPY Y(2)). Six of the 23 analogs tested possessed an NPY Y(2) IC(50) ≤ 15 nM. One member of this series, JNJ 31020028, is a selective, high affinity, receptor antagonist existing as a racemic mixture. As such a synthetic route to the desired enantiomer was designed starting from commercially available (S)-(+)-mandelic acid.

Novel tetrahydropyrido[3,2-c]pyrroles as 5-HT(7) antagonists.

The synthesis and SAR for a novel series of tetrahydropyrido[3,2-c]pyrroles is described. Optimization of the pendant aryl ring lead to high binding affinity at the 5-HT(7) receptor when small lipophilic groups were placed in the para position. Modification of the N-benzyl group and secondary amine were not well tolerated. A representative set of compounds was shown to be functional antagonists of the 5-HT(7) receptor.

2-Alkyl-4-aryl-pyrimidine fused heterocycles as selective 5-HT2A antagonists.

The synthesis and SAR for a novel series of 2-alkyl-4-aryl-tetrahydro-pyrido-pyrimidines and 2-alkyl-4-aryl-tetrahydro-pyrimido-azepines is described. Representative compounds were shown to be subtype selective 5-HT(2A) antagonists. Optimal placement of a basic nitrogen relative to the pyrimidine and the presence of a 4-fluorophenyl group in the pyrimidine 4-position was found to have a profound effect on affinity and selectivity.

Palladium-catalyzed coupling of pyrazole triflates with arylboronic acids.

[reaction: see text] A general protocol for the palladium-mediated Suzuki coupling reaction of pyrazole triflates and aryl boronic acids has been developed. The use of additional dppf ligand was determined to increase product yields allowing for the use of a broad range of reaction substrates.

Novel substituted 4-phenyl-[1,3]dioxanes: potent and selective orexin receptor 2 (OX(2)R) antagonists.

Orexins, also termed hypocretins, consist of two neuropeptide agonists (orexin A and B) interacting with two known G-protein coupled receptors (OX(1)R and OX(2)R). In addition to other biological functions, the orexin-2 receptor is thought to be an important modulator of sleep and wakefulness. Herein we describe a series of novel, selective OX(2)R antagonists consisting of substituted 4-phenyl-[1,3]dioxanes. One such antagonist is compound 9, 1-(2,4-dibromo-phenyl)-3-((4S,5S)-2,2-dimethyl-4-phenyl-[1,3]dioxan-5-yl)-urea, which is bound by the OX(2)R with a pK(i) of 8.3, has a pK(b) of 7.9, and is 600-fold selective for the OX(2)R over the OX(1)R.

Novel non-peptidic neuropeptide Y Y2 receptor antagonists.

Through SAR studies of a piperidinylindoline cinnamide HTS lead, the first potent, non-peptide, low molecular weight selective Neuropeptide Y Y2 (NPY Y2) antagonists have been synthesized. The SAR studies around the piperidinyl, the indolinyl, and the cinnamyl moieties are discussed.

Characterization of N-(1-Acetyl-2,3-dihydro-1H-indol-6-yl)-3-(3-cyano-phenyl)-N-[1-(2-cyclopentyl-ethyl)-piperidin-4yl]acrylamide (JNJ-5207787), a small molecule antagonist of the neuropeptide Y Y2 receptor.

The in vitro pharmacological properties of N-(1-Acetyl-2,3-dihydro-1H-indol-6-yl)-3-(3-cyano-phenyl)-N-[1-(2-cyclopentyl-ethyl)-piperidin-4yl]-acrylamide (JNJ-5207787), a novel neuropeptide Y Y(2) receptor (Y(2)) antagonist, were evaluated. JNJ-5207787 inhibited the binding of peptide YY (PYY) to human Y(2) receptor in KAN-Ts cells (pIC(50) = 7.00 +/- 0.10) and to rat Y(2) receptors in rat hippocampus (pIC(50) = 7.10 +/- 0.20). The compound was >100-fold selective versus human Y(1),Y(4), and Y(5) receptors as evaluated by radioligand binding. In vitro receptor autoradiography data in rat brain tissue sections confirmed the selectivity of JNJ-5207787. [(125)I]PYY binding sites sensitive to JNJ-5207787 were found in rat brain regions known to express Y(2) receptor (septum, hypothalamus, hippocampus, substantia nigra, and cerebellum), whereas insensitive binding sites were observed in regions known to express Y(1) receptor (cortex and thalamus). JNJ-5207787 was demonstrated to be an antagonist via inhibition of PYY-stimulated guanosine 5'-O-(3-[(35)S]thio)triphosphate binding ([(35)S]GTPgammaS) in KAN-Ts cells (pIC(50) corrected = 7.20 +/- 0.12). This was confirmed auto-radiographically in rat brain sections where PYY-stimulated guanosine 5'-O-(3-[(35)S]thio)triphosphate binding was inhibited by JNJ-5207787 (10 microM) in hypothalamus, hippocampus, and substantia nigra. After intraperitoneal administration in rats (30 mg/kg), JNJ-5207787 penetrated into the brain (C(max) = 1351 +/- 153 ng/ml at 30 min) and occupied Y(2) receptor binding sites as revealed by ex vivo receptor autoradiography. Hence, JNJ-5207787 is a potent and selective pharmacological tool available to establish the potential role of central and peripheral Y(2) receptors in vivo.