Tetrahydrothienopyridylbutyl-tetrahydrobenzindoles: new selective ligands of the 5-HT(7) receptor

The synthesis and the affinity for the 5-HT(7) receptor and other receptors of a novel series of fused-ring tetrahydropyridine derivatives are described. Some of the compounds showed high affinity for the 5-HT(7) receptor. Tetrahydrothienopyridylbutyl-tetrahydrobenzindoles and are potent ligands for the 5-HT(7) receptor, with high selectivity over the 5-HT(2) receptor and other receptors. These compounds should be useful tools for clarifying the biological role of the 5-HT(7) receptor.     

Benzimidazole derivatives. Part 1: Synthesis and structure-activity relationships of new benzimidazole-4-carboxamides and carboxylates as potent and selective 5-HT4 receptor antagonists

New benzimidazole-4-carboxamides 1-16 and -carboxylates 17-26 were synthesized and evaluated for binding affinity at serotonergic 5-HT4 and 5-HT3 receptors in the CNS. Most of the synthesized compounds exhibited moderate-to-very high affinity (in many cases subnanomolar) for the 5-HT4 binding site and no significant affinity for the 5-HT3 receptor. SAR observations and structural analyses (molecular modeling, INSIGHT II) indicated that the presence of a voluminous substituent in the basic nitrogen atom of the amino moiety and a distance of ca. 8.0 A from this nitrogen to the aromatic ring are of great importance for high affinity and selectivity for 5-HT4 receptors. These results confirm our recently proposed model for recognition by the 5-HT4 binding site. Amides 12-15 and esters 24 and 25 bound at central 5-HT4 sites with very high affinity (Ki = 0.11-2.9 nM) and excellent selectivity over serotonin 5-HT3, 5-HT2A, and 5-HT1A receptors (Ki > 1000-10,000 nM). Analogues 12 (Ki(5-HT4) = 0.32 nM), 13 (Ki(5-HT4) = 0.11 nM), 14 (Ki(5-HT4) = 0.29 nM) and 15 (Ki(5-HT4) = 0.54 nM) were pharmacologically characterized as selective 5-HT4 antagonists in the isolated guinea pig ileum (pA2 = 7.6, 7.9, 8.2 and 7.9, respectively), with a potency comparable to the 5-HT4 receptor antagonist RS 39604 (pA2 = 8.2). The benzimidazole-4-carboxylic acid derivatives described in this paper represent a novel class of potent and selective 5-HT4 receptor antagonists. In particular, compounds 12-15 could be interesting pharmacological tools for the understanding of the role of 5-HT4 receptors.     

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 1.

The synthesis of a series of novel 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives as well as their 5-HT(2A/2C) and H(1) receptor binding affinities are described. The in vivo activity as potential anxiolytics of the synthesised compounds was measured in a mCPP challenge test. One of the compounds, 2a, proved to be a potent 5-HT(2A/2C) receptor antagonist showing as well oral activity and therefore could be considered as a potential anxiolytic/antidepressant agent.     

Synthesis and biological evaluation of a novel structural type of serotonin 5-HT3 receptor antagonists

A series of novel 3-substituted quinoxalin-2-carboxamides were designed as per the pharmacophoric requirement for 5-HT(3) receptor antagonists and prepared by microwave irradiation and also by conventional method. The compounds were characterized by spectral data (IR, (1)H NMR, and MS) and the purity was ascertained by microanalysis. The synthesized compounds were evaluated for 5-HT(3) antagonisms in longitudinal muscle-myenteric plexus preparation from guinea pig ileum against 5-HT(3) agonist, 2-methyl-5-HT. Among the test compounds, N-{3-[(4-methylpiperazin-1-yl)methyl]-4-hydroxyphenyl}-3-methoxyquinoxalin-2-carboxamide 4e showed most favorable 5-HT(3) receptor antagonism.     

Bicyclic piperazinylbenzenesulphonamides are potent and selective 5-HT6 receptor antagonists

The synthesis of novel 3-(octahydropyrido[1,2-a]pyrazin-2-yl)- and 3-(hexahydropyrrolo[1,2-a]pyrazin-2-yl)phenyl-2-benzo[b]thiophene sulphonamide derivatives 3, (S)-4 and (R)-4 is described. The compounds show high affinity for the 5-HT6 receptor, excellent selectivity against a range of other receptors and good brain penetration.     

Phenylpyrroles, a new chemolibrary virtual screening class of 5-HT7 receptor ligands

Virtual screening studies have identified a series of phenylpyrroles as novel 5-HT7 receptor ligands. The synthesis and the affinity for the 5-HT7 receptor of these phenylpyrroles are described. Some of these compounds exhibited high affinity for the 5-HT7 receptors.     

Microwave assisted synthesis of 2-(4-substituted piperazin-1-yl)-1,8-naphthyridine-3-carbonitrile as a new class of serotonin 5-HT3 receptor antagonists

A series of novel 2-(4-substituted piperazin-1-yl)-1,8-naphthyridine-3-carbonitrile 6 were prepared by microwave irradiation and conventional heating. The intermediate, 2-oxo-1,2-dihydro-1,8-naphthyridine-3-carbonitrile 3, was prepared from 2-aminonicotinaldehyde 1 and ethyl cyanoacetate 2 in the presence of piperidine under solvent free condition. The synthesized compounds were evaluated for 5-HT3 antagonisms in longitudinal muscle-myenteric plexus (LMMP) preparation from Guinea pig ileum against 5-HT3 agonist, 2-methyl-5-HT. Among the compounds tested, 2-(4-allylpiperazin-1-yl)-1,8-naphthyridine-3-carbonitrile 6d showed most favorable 5-HT3 receptor antagonism in the Guinea pig ileum.     

Novel 3-aminochromans as potential pharmacological tools for the serotonin 5-HT(7) receptor

The synthesis of novel C6-aryl substituted derivatives of 3-(dimethylamino)chroman is described. The novel derivatives display 5-HT(7) receptor affinities that varies from nM to muM, indicating that this small set of derivatives constitute a novel and interesting starting point for further structure-serotonin 5-HT(7) activity relationship (SAR) studies.     

Indoline derivatives as 5-HT(2C) receptor agonists

A series of 1-(1-indolinyl)-2-propylamines was synthesised and evaluated as 5-HT(2C) receptor agonists for the treatment of obesity. The general methods of synthesis of the precursor indoles are described. The functional efficacy and radioligand binding data for all of the compounds at 5-HT(2) receptor subtypes are reported. A number of compounds were found to reduce food intake in rats after oral administration.     

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 2.

Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described.     

Synthesis of 3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles,displaying combined 5-HT uptake inhibiting and alpha(2)-adrenoceptor antagonistic activities: a novel series of potential antidepressants

The synthesis of a series of novel 3-piperazinylmethyl-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles as novel dual 5-HT reuptake inhibitors and alpha(2)-adrenoceptor antagonists is described. Their affinity at the three different human alpha(2)-adrenoceptor subtypes and the 5-HT transporter site is reported. The in vivo activity of the compounds was measured in two different assays: (1). inhibition of pCA-induced excitation, which evaluates the ability to block the central 5-HT transporter, and (2). inhibition of xylazine-induced loss of righting, which evaluates the ability to block central alpha(2)-adrenoceptors.     

Pyrrolo(iso)quinoline derivatives as 5-HT(2C) receptor agonists

A series of 1-(1-pyrrolo(iso)quinolinyl)-2-propylamines was synthesised and evaluated as 5-HT(2C) receptor agonists for the treatment of obesity. The general methods of synthesis of the precursor indoles are described. The functional efficacy and radioligand binding data for the compounds at 5-HT(2) receptor subtypes are reported. The analogue which showed the highest 5-HT(2C) binding affinity (27, 1.6nM) was found to be successful in reducing food intake in rats.     

Parallel solid-phase synthesis and characterization of new sulfonamide and carboxamide proline derivatives as potential CNS agents

A solid-phase synthesis of the 64-member library of novel sulfonamide and carboxamide proline derivatives, focused on the 5-HT7 receptor antagonist SB-258741, was described. The final compounds were obtained in good yields and high purity upon cleavage from SynPhase Lanterns, functionalized by a BAL linker. The library representatives were screened for 5-HT7, 5-HT1A and D2 receptors to explore the impact of a tertiary amine moiety, the length of an alkylene spacer and the aryl fragment on the receptor affinity. The preliminary biological results provided data for further investigation aimed at a search for 5-HT7 receptor agents, and permitted the identification of several compounds with significant 5-HT1A receptor affinity.     

4-(2-Aminoethoxy)-N-(phenylsulfonyl)indoles as novel 5-HT6 receptor ligands

The preparation of a novel class of 4-(2-aminoethoxy)-N-(phenylsulfonyl)indoles which exhibit high affinity towards the 5-HT6 receptor is reported here. Among these compounds, 4-(2-methylaminoethoxy)-N-(phenylsulfonyl)indole 5g showed superior affinity (Ki = 1 nM) towards the 5-HT6 receptor as well as excellent selectivity (> 2000-fold) against the closely related subtype 5-HT7 receptor.     

Synthesis and structure-activity relationship of 2-(aminoalkyl)-3,3a,8,12b-tetrahydro-2H-dibenzocyclohepta[1,2-b]furan derivatives: a novel series of 5-HT(2A/2C) receptor antagonists

Following the program started at Johnson & Johnson Pharmaceutical Research & Development searching for 5-HT(2A/2C) antagonists we now report on the synthesis of a series of substituted 2-(aminomethyl)-3,3a,8,12b-tetrahydro-2H-dibenzocyclohepta[1,2-b]furan derivatives. The 5-HT2A, 5-HT2C and H1 receptor affinities of the described compounds are reported. The mCCP antagonistic activity of a set of selected molecules is also reported.     

Structural determinants for high 5-HT(2A) receptor affinity of spiro[9,10-dihydroanthracene]-9,3(')-pyrrolidine (SpAMDA)

The synthesis and 5-HT(2A) receptor affinities of ring altered derivatives of spiro[9,10-dihydroanthracene]-9,3(')-pyrrolidine (4), a structurally unique tetracyclic 5-HT(2A) receptor antagonist, are described. The characteristics of the parent compound prove to be necessary for optimal 5-HT(2A) receptor affinity. However, expansion of the size of the pyrrolidine and central rings produce compounds with reasonably high 5-HT(2A) receptor affinities. In addition, the parent compound is shown to have high 5-HT(2) receptor selectivity.     

Novel aminoethylbiphenyls as 5-HT7 receptor ligands

The synthesis of a series of aminoethylbiphenyls as novel 5-HT(7) receptor ligands is described. The novel derivatives exhibit high affinity for the 5-HT(7) receptor with selectivity toward 5-HT(1A) receptor.     

Design, synthesis, and preliminary in vitro and in vivo pharmacological evaluation of 2-{4-[4-(2,5-disubstituted thiazol-4-yl)phenylethyl]piperazin-1-yl}-1,8-naphthyridine-3-carbonitriles as atypical antipsychotic agents

A series of 2-{4-[4-(2,5-disubstituted thiazolyl)phenylethyl] piperazin-1-yl}-1,8-naphthyridine-3-carbonitriles were synthesized in an effort to prepare novel atypical antipsychotic agents. The compounds were synthesized either by microwave irradiation technique or by conventional synthesis and were characterized by spectral data (IR, (1)H NMR, and MS) and the purity was ascertained by microanalysis. The D(2) and 5-HT(2A) affinity of the synthesized compounds was screened in vitro by radioligand displacement assays on membrane homogenates isolated from rat striatum and rat cortex, respectively. Furthermore, all the synthesized compounds were screened for their in vivo pharmacological activity in Swiss albino mice. The D(2) antagonism studies were performed using climbing mouse assay model and 5-HT(2A) antagonism studies were performed using quipazine-induced head twitches in mice. It was observed that none of the new chemical entities exhibited catalepsy and 10f is the most active among the synthesized compounds with 5-HT(2A)/D(2) ratio of 1.1286 although the standard drug risperidone exhibited 5-HT(2A)/D(2) ratio of 1.0989.     

Synthesis of new 1,2,3-benzotriazin-4-one-arylpiperazine derivatives as 5-HT1A serotonin receptor ligands

A series of novel 1,2,3-benzotriazin-4-one derivatives was prepared and evaluated as ligands for 5-HT receptors. Radioligand binding assays proved that the majority of the novel compounds behaved as good to excellent ligands at the 5-HT1A receptor, some of which were selective with respect 5-HT2A and 5-HT2C receptors. Six analogues (1a, 2a, 2b, 2c, 2e and 2i) were selected and further evaluated for their binding affinities on D1, D2 dopaminergic and alpha1-, alpha2-adrenergic receptors. A o-OCH3 derivative (2e) bound at 5-HT1A sites with subnanomolar affinity (IC50 = 0.059 nM) and shows high selectivity over all considered receptors and may offer a new lead for the development of therapeutically efficacious agents.     

Novel N-[1-(1-substituted 4-piperidinylmethyl)-4-piperidinyl]benzamides as potent colonic prokinetic agents

A series of novel N-[1-(1-substituted 4-piperidinylmethyl)-4-piperidinyl]benzamides was prepared and its compounds were evaluated for their binding to 5-HT(4) receptors and effects on gastrointestinal motility in conscious dogs. 4-Amino-N-[1-[1-(4-aminobutyl)-4-piperidinylmethyl]-4-piperidinyl]-5-chloro-2-methoxybenzamide (15) was found to have a potent binding affinity for 5-HT(4) receptors (IC(50): 6.47nM) and showed excellent colonic prokinetic activity.