3H]N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine ([3H]BTCP): a new phencyclidine analog selective for the dopamine uptake complex

A benzothiophenyl group instead of a phenyl ring on phencyclidine (PCP) yields a molecule N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine (BTCP), which is one of the more potent known dopamine (DA) uptake inhibitors (IC50 = 7 nM). This compound also has low affinity for the PCP receptor (K0.5 = 6 microM). The sodium-dependent [3H]BTCP binding to rat striatal membranes was investigated. [3H]BTCP bound to two different sites: one with very high affinity (Kd1 = 0.9 nM, Bmax1 = 3.5 pmol/mg protein) which paralleled the distribution of dopaminergic nerve endings and a second with lower affinity (Kd2 = 20 nM, Bmax2 = 7.5 pmol/mg protein). There was a good correlation between the abilities of drugs specific for the DA uptake complex and of PCP analogs to inhibit high affinity [3H]BTCP binding and [3H]DA synaptosomal uptake. This study also demonstrated that PCP interacts with the DA uptake site since it is a competitive inhibitor of high affinity [3H]BTCP binding. This site, however, is not the PCP receptor, which has a different pharmacological selectivity.     

Modulation by dopamine of [3H]N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine ([3H]BTCP, a phencyclidine derivative) binding to the dopamine uptake complex.

The modulation by dopamine of the binding of [3H]BTCP to the dopamine (DA) uptake complex was investigated in vivo (in control, reserpine- and L-DOPA-treated mice) and in vitro (on membrane preparations of the striatum of the rat). In both cases increasing doses of DA exerted a non-competitive inhibition of binding of [3H]BTCP, with a Ki value close to its K0.5, determined in competition experiments. Amphetamine and cocaine were also non-competitive inhibitors of the binding of [3H]BTCP, while GBR 12783 was competitive. In the presence of DA, the amount of cocaine required to inhibit the binding of [3H]BTCP was increased both in vitro and in vivo. These results suggest that inhibitors of the uptake of DA, such as BTCP or GBR 12783, modulate allosterically the uptake of DA, by binding to a site different from the DA recognition site. Cocaine, however, seems to share the same recognition site as DA.     

Pharmacological characterization of the discriminative stimulus properties of the phencyclidine analog, N-[1-(2-benzo(b)thiophenyl)-cyclohexyl]piperidine

Rationale: Although both cocaine and the phencyclidine analog, BTCP, have dopamine (DA) re-uptake blocking properties, under some conditions their behavioral effects can be differentiated. Therefore, we examined whether the discriminative stimulus (DS) effects of BTCP are different from those of cocaine. Objectives: To compare the effects of monoamine re-uptake blockers, varying in their in vitro potencies as inhibitors of DA, norepinephrine (NE), or serotonin re-uptake, in different groups of rats trained to discriminate either BTCP or cocaine from saline. Additionally, drugs from other pharmacological classes were tested in both groups. Methods: Rats were trained to discriminate either BTCP (5 mg/kg, i.p.) or cocaine (10 mg/kg, i.p.) from saline under a two-lever FR10 drug discrimination procedure. Results: BTCP and cocaine cross-substituted in BTCP- and cocaine-trained rats. The DA re-uptake blockers, mazindol, indatraline, methylphenidate, GBR12909, and GBR12935, occasioned dose-related drug-lever (DL) selection both in cocaine- and in BTCP-trained rats, with potencies that were significantly correlated. In contrast, the NE re-uptake blockers, nisoxetine, desipramine, and nortriptyline, produced higher levels of DL selection in BTCP-trained rats than in cocaine-trained rats, a profile like that reported in low-dose cocaine-trained rats. Drugs from other classes acted similarly in both discriminations. Further, the α₁-adrenergic antagonist prazosin dose dependently blocked the DS effects of the training dose of BTCP, but not of cocaine. Conclusions: Theresults suggest that the DS effects of BTCP are similar to cocaine, and resemble those of a low training dose of cocaine. Received: 6 October 1998 / Final version: 19 March 1999     

Inhibition of locus coeruleus neurons by the phencyclidine analog, N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine: evidence for potent indirect adrenoceptor agonist properties.

The effects of the phencyclidine derivative, N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine (BTCP), on the electrical activity of noradrenaline (NA) neurons of the locus coeruleus (LC) were studied in halothane-anesthetized rats. Systemic administration of BTCP potently inhibited LC neurons (ID50 of 1.1 +/- 0.1 mg/kg i.v.). This effect was mimicked by local microejection of BTCP into the LC. Both the systemic and local effects of BTCP were blocked by alpha 2-adrenoceptor antagonists and prevented by prior depletion of catecholamines with reserpine. These and other data suggest that BTCP behaves as a potent indirect NA agonist (i.e. via NA re-uptake and/or release systems).     

Synthesis of high specific activity (3,4-[3H]cyclohexyl)-N-[1 (2-benzo[b]thienyl)cyclohexyl]piperidine {[3H]BTCP}: A selective probe for the dopamine-reuptake complex

High specific activity [³H]BTCP, a radioligand for the dopaminereuptake complex was synthesized in 7-steps starting with the readily available starting materials, cyclohexane-1,4-dione monoethylene ketal and benzo[b]thiophene; the tritium label was introduced in the final step on the 3- and 4- positions of the cyclohexyl ring by catalytic tritiation of N-[4-(2-benzo[b]thienyl)cyclohexenyl]piperidine to give [³H]BTCP in 7.3% yield with a specific activity of 29.8 Ci/mmol (51.4% isotopic incorporation).     

The pharmacokinetics of [3H]1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) in Sprague-Dawley rats

Using adult male Sprague-Dawley rats, we examined the blood protein binding and pharmacokinetics of the potent phencyclidine (PCP) receptor ligand 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP). The average percentage of unbound [3H]TCP in rat serum was 42 +/- 6% and the [3H]TCP blood to plasma ratio was 0.98 +/- 0.03 (mean +/- SD, n = 5 in both studies). For the pharmacokinetic studies, [3H]TCP and 1 mg/kg unlabeled TCP were administered as an iv bolus dose. The average [3H]TCP elimination half-life was 2.1 hr. In contrast, total radioactivity in the plasma had a much longer half-life, suggesting much slower metabolite elimination. The average distribution volumes were 27 +/- 17, 15.6 +/- 6.2, and 5.6 +/- 3.0 liters/kg for V beta, Vss, and Vc, respectively. Total body and renal clearance values were 132 +/- 45 and 1.1 +/- 0.4 ml/min/kg, respectively. When TCP pharmacokinetic parameters were compared to PCP pharmacokinetic data in rats from a previous study, a strikingly similar pharmacokinetic profile was found. These data indicated that TCP and PCP are equivalent, from a pharmacokinetic point of view, and that the higher pharmacological potency of TCP over PCP is probably due to receptor-mediated differences.     

1-[1-(2-Benzo[b]thiopheneyl)cyclohexyl]piperidine hydrochloride (BTCP) yields two active primary metabolites in vivo. Identification and quantification of BTCP primary metabolites in mice plasma, urine, and brain and their affinity for the neuronal dopamine transporter.

1-[1-(2-Benzo[b]thiopheneyl)cyclohexyl]piperidine hydrochloride (BTCP) and cocaine bind to the neuronal dopamine transporter (DAT) to strongly inhibit dopamine (DA) reuptake. Although similar to acute administration, cocaine and BTCP produce sensitization and tolerance, respectively, on chronic administration. We previously found that liver microsomes produced two primary metabolites from BTCP with a high affinity for DAT. Because such metabolites, if produced in vivo, could account for the pharmacological difference with cocaine, it was important to compare BTCP biotransformations in vitro and in vivo. Therefore, we identified and quantified BTCP and primary metabolites in mice urine, plasma, and brain after acute i.p. administration. The low recovery yield suggest that BTCP might behave like its close analogue, phencyclidine, with long-term storage of metabolites. Two active metabolites found in vitro were found in mice brain with estimated half-life values similar to that of BTCP (0.3 h). Although respective brain concentrations were 20 and 40 times lower than that of BTCP, their potency to displace in vivo [³H]BTCP bound to the DAT was 50 and 10 times higher, respectively, than that of BTCP. They could, therefore, contribute to the inhibition of DA transport and play an important role in BTCP pharmacology. They could also explain the differences between BTCP and cocaine on repeated administration.     

Novel piperidine derivatives. Synthesis and anti-acetylcholinesterase activity of 1-benzyl-4-[2-(N-benzoylamino)ethyl]piperidine derivatives

A series of 1-benzyl-4-[2-(N-benzoylamino)ethyl]piperidine derivatives was synthesized and evaluated for anti-acetylcholinesterase (anti-AChE) activity. Substituting the benzamide with a bulky moiety in the para position led to a substantial increase in activity. Introduction of an akyl or phenyl group at the nitrogen atom of benzamide dramatically enhanced the activity. The basic quality of the nitrogen atom of piperidine appears to play an important role in the increased activity, since the N-benzoylpiperidine derivative was almost inactive. We found that 1-benzyl-4-[2-(N-[4'-(benzylsulfonyl) benzoyl]-N-methylamino]ethyl]piperidine hydrochloride (21) (IC50 = 0.56 nM) is one of the most potent inhibitors of acetylcholinesterase. Compound 21 showed an affinity 18,000 times greater for AChE than for BuChE. At a dose of 3 mg/kg, 21 produced a marked and significant increase in acetylcholine (ACh) content in the cerebral vortex and hippocampus of rats. Compound 21 was chosen for advanced development as an antidementia agent.     

beta-Adrenoceptor blocking activity of 3-alkylamino-1-(3-benzo[ b ]thienyloxy)-2-propanols and closely related bicyclic compounds

A preliminary pharmacological study of a thiophenic isoster of propranolol and related compounds with a tert. butylamino or homoveratrylamino group instead of the isopropylamino group is described. The synthesis and some pharmacological properties of derivatives in which the benzene ring is replaced by a cyclopentene or cyclohexene ring are also reported. Compounds carrying the tert. butylamino moiety turned out to be similar to propranolol in their pharmacological properties.     

1-[1-(2-Benzo[b]thiopheneyl)cyclohexyl]piperidine hydrochloride (BTCP) yields two active primary metabolites in vivo: Identification and quantification of BTCP primary metabolites in mice plasma, urine, and brain and their affinity for the neuronal dopamine transporter

1-[1-(2-Benzo[b]thiopheneyl)cyclohexyl]piperidine hydrochloride (BTCP) and cocaine bind to the neuronal dopamine transporter (DAT) to strongly inhibit dopamine (DA) reuptake. Although similar to acute administration, cocaine and BTCP produce sensitization and tolerance, respectively, on chronic administration. We previously found that liver microsomes produced two primary metabolites from BTCP with a high affinity for DAT. Because such metabolites, if produced in vivo, could account for the pharmacological difference with cocaine, it was important to compare BTCP biotransformations in vitro and in vivo. Therefore, we identified and quantified BTCP and primary metabolites in mice urine, plasma, and brain after acute i.p. administration. The low recovery yield suggest that BTCP might behave like its close analogue, phencyclidine, with long-term storage of metabolites. Two active metabolites found in vitro were found in mice brain with estimated half-life values similar to that of BTCP (0.3 h). Although respective brain concentrations were 20 and 40 times lower than that of BTCP, their potency to displace in vivo [³H]BTCP bound to the DAT was 50 and 10 times higher, respectively, than that of BTCP. They could, therefore, contribute to the inhibition of DA transport and play an important role in BTCP pharmacology. They could also explain the differences between BTCP and cocaine on repeated administration.     

Synthesis of 3-(3-pyridyl)- and 3-(3-benzo[b]thienyl)-D-alanine

The DL-arylamino acid ethyl ester derivatives of β-(3-pyridyl)-DL-alanine, and β-(3-benzo[b]thienyl)-DL-alanine were synthesized by diethyl acetamidomalonate condensation with the respective arylmethyl halides followed by partial hydrolysis to the monoethyl ester and decarboxylation. Each derivative was enzymatically resolved to a separable mixture of the corresponding N-acetyl-L-amino acid and the unchanged D amino acid derivative. Acidic hydrolysis of the latter gave the corresponding D-amino acid, the optical purity of which was established by HPLC analysis of the 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate (GITC) derivative. The free D amino acids were converted to D-BOC derivatives by reaction with di-tert-butyldicarbonate in tert-butyl alcohol, water and sodium hydroxide.     

N-[2-(4-甲氧基苯基)-1-甲基乙基]苄胺的制备

以1-（4-甲氧基苯基）丙酮-2和N-苄基甲酰胺为原料,采用“一锅法”,经N-苄基化、Leuckart反应和酸性水解制得福莫特罗的重要中间体N-[2-（4-甲氧基苯基）-1-甲基乙基]苄胺,总收率约46%。     

Synthetic analgesics: N-(1-[2-arylethyl]-4-substituted 4-piperidinyl) N-arylalkanamides.

The synthesis of several 4-arylamino-4-piperdinecarboxylic acids is reported. These acids were starting materials for the preparation of alpha-amino esthers, ethers and ketones. Different synthetic approaches are described. Suitable substitution on both nitrogen atoms afforded extremely potent analgesics. Thus, methyl 4-[N-(1-oxopropyl)-N-phenylamino]-1-(2-phenylethyl)-4-piperidinecarboxylate (22),N-(4-(methoxymethyl)-2-[2-(2-thienyl)ethyl]-4-piperidinyl)-N-phenylpropranamide (67) and N-[4-acetyl-1-(2-phenylethyl)-4-piperidinyl]-N-phenylpropanamide (82) were found to be respectively 7682, 3987 and 4921 times as potent as morfine. Both cis- and trans-3-methyl homologs of 22 have been prepared. As expected, analgesic activity resides mainly in the cis-isomer.     

5-Chloro-2-phenyl-1-benzo[b]thiophene-3-alkanimines, potential antipsychotic agents.

The title compounds (most notably 2a) were synthesized on the basis of the N-methylation hypothesis of schizophrenia. They were evaluated in dopamine and haloperidol receptor assays. The binding characteristics were comparable in some cases to known neuroleptics.     

N-[omega-[4-(2-methoxyphenyl)-1-piperazinyl]alkyl]-2-quinolinamines as high-affinity fluorescent 5-HT1A receptor ligands

We here report on the design, synthesis, binding affinities, and fluorescent properties of a series of serotonin 5-HT 1A receptor ligands, with N-[omega-[4-(2-methoxyphenyl)-1-piperazinyl]alkyl]-2-quinolinamine structure. Several of the new ligands displayed nanomolar affinity at 5-HT 1A receptor and good fluorescent properties. In particular, derivative 24 showed a favorable combination of 5-HT 1A receptor affinity ( K i = 0.4 nM), Stokes shift (excitation wavelength = 381 nm, emission wavelength = 455 nm), and quantum yield in ethanol (Phi = 0.45).     

Studies of thioamides and their derivatives. VIII. Products of decomposition of quaternary salts of 1-[alpha-alkylthio-p-dimethyl- amino)benzylidene]piperidine and 1-[alpha-alkylthio-(p-trialkyl- ammonio)benzylidene]piperidine

Products of decomposition of eight quaternary salts, derivatives of 1-[alpha-alkylthio-(p-dimethylamino)benzylidene]-piperidinium, in water, ethanol, pyridine and glacial acetic acid were investigated. IR and UV spectra of the obtained decomposition products were measured, and the compounds were tested for cytostatic activity.     

帕尼培南关键中间体的合成

目的: 改进帕尼培南关键中间体(S)-1-[N-(对硝基苄氧羰基)-1-亚胺基乙基]-3-巯基吡咯烷的合成工艺。方法:以对硝基苄醇为起始原料,经酰化、缩合、与3-R-羟基吡咯烷发生N-烃基化反应,再经磺酰化、缩合、水解反应得到目标化合物。结果与结论:以对硝基苄醇为起始原料经6步反应得到目标化合物,结构经IR、1H-NMR、MS谱图数据确证,比旋光度值与文献报道一致。改进后的工艺总收率为37.2%,各步反应操作简便,条件温和,更适合工业化生产。     

(S)-1-(N-烯丙氧羰基)亚胺乙基-3-巯基吡咯烷的合成

目的 合成帕尼培南关键中间体 (S)-1-( N-烯丙氧羰基)亚胺乙基-3-巯基吡咯烷。方法 以氯甲酸烯丙酯为酰化剂,与盐酸乙脒进行 N-酰化反应得到 1-亚胺乙基氨基甲酸烯丙酯,该化合物与 3-R-羟基吡咯烷进行缩合,再经甲磺酰化、S_N2 取代、水解共 5 步反应得到目标化合物。结果与结论 该合成路线中使用新型保护基烯丙氧羰基替代传统的保护基—对硝基苄氧羰基,目标化合物的结构经 ¹H-NMR、MS 谱确证,总收率为 41.6%,各步反应操作简便,条件温和,有利于工业化生产。