Amide, urea, and carbamate analogues of the muscarinic agent [4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]trimethylammonium chloride.

A series of amide, urea, and carbamate analogues of the muscarinic (M1) ganglionic stimulant [4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]trimethylammonium chloride (McN-A-343; 1) was prepared. The C1-methyl-substituted carbamates 8-11 were resolved into the enantiomers. In order to investigate the ganglionic stimulant activity and affinity of the new compounds we studied their ability to increase mean arterial blood pressure (MAP) in the pithed rat and their ability to displace the M1 receptor selective antagonist [3H]pirenzepine from rabbit sympathetic ganglia. The quaternary ammonium derivatives of 1, but not their corresponding tertiary amines, displayed ganglionic stimulant properties. The urea derivative 14 and the acetamide derivative 18 were almost equipotent to 1 as ganglionic agonists. In addition, 14 and 18 showed only 2- to 3-fold less affinity to ganglionic muscarinic receptors than 1. Introduction of a methyl group in the 1 position of the butynyl chain of 1 and its 4-chlorophenyl analogue increased ganglionic stimulant potency. The resulting (+/-)-9 and (+/-)-11 were the most potent analogues in this study. They were found to be partial agonists and showed 5- and 16-fold higher potency than 1, respectively, in increasing the MAP. They also displayed 6- and 18-fold higher affinity than 1 for ganglionic M1 receptors. The (S)-enantiomers of 9 and 11 were 1.5- and 4.9-fold more potent, respectively, than their antipodes as ganglionic muscarinic stimulants. The C1-methyl-substituted urea and acetamide derivatives (15 and 19) were 1.5- and 3-fold less potent than 1 and displayed several-fold lower affinity for ganglionic M1 receptors. The new quaternary analogues retained the selectivity for ganglionic muscarinic receptors since they produced weak partial agonist effects on the guinea pig ileum and showed several-fold lower nicotinic activity than 1 in the frog rectus abdominis assay.     

Muscarinic ganglionic stimulants: conformationally restrained analogues related to [4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]trimethylammonium chloride

The synthesis of a series of tertiary and quaternary cyclic analogues (isoarecolinol, dihydroisoarecolinol, arecolinol, and 3-pyrroline-3-carbinol derivatives) of [4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]trimethylammonium chloride (McN-A-343) (1), a selective stimulant of muscarinic receptors in sympathetic ganglia (so-called M1 receptors), is reported. The compounds 3-10 were tested for muscarinic ganglion-stimulating activity by recording blood pressure responses in pithed rats. All tertiary compounds tested had no ganglion-stimulating activity. Among the series of quaternary derivatives, only the isoarecolinol analogues 4a and 4b showed considerable ganglion-stimulating effects, whereas the dihydroisoarecolinol (8), the arecolinol (6a, 6b), and the 3-pyrroline-3-carbinol derivatives (10) were much less potent. Our experiments therefore demonstrate that in this series a quaternary nitrogen atom, unsaturation at C2 of the ammonium side chain, and a certain spatial arrangement of the ammonium and the phenylcarbamate groups are essential for potent M1-receptor stimulating activity.     

Tertiary 2-haloethylamine derivatives of the muscarinic agent McN-A-343, [4-[[N-(3-chlorophenyl)carbamoyl]oxy]-2-butynyl]trimethylammonium chloride

4-[(2-Chloroethyl)methylamino]-2-butynyl N-(3-chlorophenyl)carbamate (2) and 4-[(2-bromoethyl)methylamino]-2-butynyl N-(3-chlorophenyl)carbamate (3) were synthesized. Compounds 2 and 3 cyclized at neutral pH to an aziridinium ion (4). The rate constants for the cyclization of 2 and 3 at 37 degrees C were about 0.01 and 0.4 min-1, respectively, as measured by titrimetric analysis and by 1H NMR spectroscopy. The aziridinium ion had 1/4 the potency of McN-A-343 (1) as a ganglionic muscarinic stimulant in the anesthetized, pentolinium-treated rat but showed no muscarinic effects on the isolated guinea pig ileum. It caused alkylation of muscarinic receptors in homogenates of the rat cerebral cortex. An irreversible blockade of central muscarinic receptors was also observed after intravenous administration of 3 to mice. Because of its selectivity, irreversible actions, and ability to pass into the central nervous system, 3 should become a valuable tool in studies of muscarinic receptors.     

Stereochemical analogs of a muscarinic, ganglionic stimulant. 2. Cis and trans olefinic, epoxide, and cyclopropane analogs related to 4-(N-(3-chlorophenyl)carbamoyloxy]-2-butynyltrimethylammonium chloride (McN-A-343).

Preparation of analogs of 4-[N-(3-chlorophenyl) carbamoyloxy]-2-butynyltrimethylammonium chloride [1 (McN-A-343)], cis- and trans-4-[N-(4-chlorophenyl)carbamoyloxy]-2-butenyltrimethylammonium iodides (5 and 6), and the corresponding epoxides and cyclopropanes is reported. Pharmacological testing for ganglion-stimulating activity demonstrated that the trans olefin 6 and trans epoxide 8 have properties similar to 1, while the trans cyclopropane analog 10 was inactive. All cis compounds were inactive. The muscarinic ganglion-stimulating properties of the active compounds are interpreted in terms of similar fit at the receptor level by the alkyltrimethylammonium ion and the ether oxygen 5.7 A distant, as well as an electron-rich center midway between groups in the form of a double bond or unshared electron pairs. Comparison of smooth muscle and ganglion-stimulating properties of the compounds showed that trans epoxide 8 was the most selective for muscarinic ganglionic sites.     

Synthesis and pharmacological evaluation of enantiomerically pure 4-deoxy-4-fluoromuscarines.

Four isomers of [(4-fluoro-5-methyl-tetrahydrofuran-2-yl)methyl]trimethylammonium iodide (4-deoxy-4-fluoro-muscarines) were prepared in enantiomerically and diastereomerically pure form from (S)-(-)-methyl 4-methylphenyl sulfoxide, ethyl fluoroacetate, and allyl bromide. Their absolute configurations were assigned by 1H NMR analyses. The four optically pure compounds were tested in vitro on guinea pig and their muscarinic potency was evaluated at M3 (ileum and bladder) and M2 (heart) muscarinic receptor subtypes. Compound 1a, the most potent isomer of the series, was also tested in vivo on pithed rat and its muscarinic activity at the M1 receptor subtype was compared with that of muscarine. Moreover, affinity and relative efficacy were calculated in vitro for this compound at M2 (heart force and rate) and M3 (ileum and bladder) receptors in order to investigate muscarinic receptor heterogeneity. The 4-deoxy-4-fluoromuscarines display a similar trend of potency as the corresponding muscarines and compound 1a shows differences in the affinity constants among the studied tissues. Replacement of a hydroxyl group for a fluorine atom in the 4 position of muscarine produces 1 order of magnitude increase in affinity for cardiac M2 muscarinic receptors controlling rate, while the affinity at cardiac M2 muscarinic receptors controlling force is unchanged, opening the possibility of a further classification of cardiac muscarinic receptors.     

Synthesis of 5-(4-alkylsulfanyl-[1, 2, 5]thiadiazol-3-yl)-3-methyl-1, 2, 3, 4-tetrahydropyrimidine oxalate salts and their evaluation as muscarinic receptor agonists

The synthesis and biological test of 5-(4-alkylsulfanyl-[1, 2, 5]thiadiazol-3-yl)-3-me-thyl-1, 2, 3, 4-tetrahydropyrimidine oxalate salts 7 as muscarinic receptor agonists are described. The key intermediate 4 was obtained by a modified Strecker reaction and cyclization, and the 3-methyl-1, 2, 3, 4-tetrahydropyrimidines were obtained by subsequent substitution, quarternization, and reduction. The final products 7 were obtained as oxalic acid salts. The prepared compounds were examined in vitro for their binding affinities to the cloned human muscarinic receptor by the [(3)H]-NMS binding assay.     

Alkylating partial muscarinic agonists related to oxotremorine. N-[4-[(2-haloethyl)methylamino]-2-butynyl]-5-methyl-2-pyrrolidones

N-[4-[(2-Chloroethyl)methylamino]-2-butynyl]-5-methyl-2-pyrrolidone (3) and N-[4-[(2-bromoethyl)methylamino]-2-butynyl]-5-methyl-2- pyrrolidone (4) were synthesized. Compounds 3 and 4 cyclized in neutral aqueous solution to an aziridinium ion (4A). The rate constants for the cyclization of 3 and 4 at 37 degrees C were 0.025 and 0.89 min-1, respectively. The aziridinium ion was equipotent with carbachol as a muscarinic agonist on the isolated guinea pig ileum. It was more potent than the corresponding 2-pyrrolidone derivative (2A) in alkylating muscarinic receptors in homogenates of the rat cerebral cortex. This higher potency was due to greater receptor affinity of 4A as compared to 2A rather than to greater rate constant for alkylation of muscarinic receptors. These properties of 3 and 4 and their low toxicity should make them valuable tools for receptor inactivation studies in vivo and in vitro.     

Muscarinic receptor binding and activation of second messengers by substituted N-methyl-N-[4-(1-azacycloalkyl)-2-butynyl]acetamides.

A series of substituted azacycloalkyl analogues of the muscarinic agonist UH 5 (N-methyl-N-[4-(1-pyrrolidinyl)-2-butynyl]acetamide, 1a) were synthesized and evaluated pharmacologically. These compounds were developed as intermediates for further derivatization leading to functionalized congeners of 1a. The compounds were synthesized by using a Mannich-type condensation of N-acetyl-N-methylpropargylamine to various substituted saturated azaheterocycles. The compounds were screened at a single concentration in competitive binding assays in rat cerebral cortical membranes against either [3H]N-methylscopolamine (at 100 microM) or [3H]oxotremorine-M (at 1 microM) labels. Candidates were then selected for further evaluation of their effect on phosphoinositide (PI) turnover in membranes from A9L cells transfected with cDNA of either m1-muscarinic cholinergic receptors (m1AChRs) or m3AChRs. The analogues were also tested for the inhibition of adenylate cyclase in NG108-15 cells expressing m4AChRs. The azetidine analogue of 1a had a Ki value of 12 nM for the inhibition of [3H]oxotremorine-M binding in rat brain and had an agonist potency at m1-,m3-, and m4AChRs comparable to 1a. The substituted 5- and 6-member ring analogues generally had lower binding affinities and were less potent than 1a in stimulating PI turnover. Several compounds were moderately effective in inhibiting cyclic AMP production in NG108-15 cells.     

Functionalized congener approach for the design of novel muscarinic agents. Synthesis and pharmacological evaluation of N-methyl-N-[4-(1-pyrrolidinyl)-2-butynyl] amides

A functionalized congener approach was used to design ligands for muscarinic cholinergic receptors (mAChRs). A series of omega-functionalized alkyl amides of N-methyl-4-(1-pyrrolidinyl)-2-butynamine (22) were prepared as functionalized analogues of UH 5 [N-methyl-N-[4-(1-pyrrolidinyl)-2-butynyl]acetamide], a muscarinic agonist related to oxotremorine. Intermediate 22 was coupled to a series of Boc-protected omega-amino acids, and the resulting amides were deprotected and acylated. Intermediate 22 was also acylated with succinic anhydride and derivatized. The synthetic intermediates and final compounds were evaluated in vitro for their effects on the turnover of phosphatidylinositides in SK-N-SH human neuroblastoma cells that express m3AChRs, and on the production of cyclic AMP in NG108-15 neuroblastoma x glioma cells that express only m4AChRs. The displacement of [3H]-N-methylscopolamine was also measured in membrane preparations from each of these cell lines. Conjugates of glycine and beta-alanine were agonists at m4AChRs, having little or no activity at m3AChRs. The potency in displacement of [3H]-N-methylscopolamine from both m3- and m4AChRs generally increased with increasing chain lengths of the omega-aminoalkyl congeners. The amides of 7-aminoheptanoic acid and 8-aminooctanoic acid, and their Boc-protected derivatives, had comparable affinities to UH 5 (Ki = 5.0 and 4.5 microM at m3AChRs and at m4AChRs, respectively) at both receptors but lacked any agonist effects.     

The use of different agonists in antagonist affinity constant estimations.

1 The affinities of 4 muscarinic antagonists were estimated on intact pieces of guinea-pig ileum using the agonists carbachol and pentyl trimethylammonium both in separate experiments and in the same experiment. 2 The apparent affinities were slightly but consistently higher when estimated from the responses produced by pentyl trimethylammonium than when estimated from the responses produced by carbachol. 3 This difference was greatly reduced or abolished if totally denervated logitudinal muscle strips were used rather than intact pieces of ileum. It is therefore suggested that the difference is due to the presence of receptors in the ganglionic layer. 4 To explain the difference in apparent affinity of the antagonists these receptors can not be identical to the muscarinic receptors on the smooth muscle. 5 In addition they can not be nicotinic ganglionic receptors as the difference did not appear to be affected by the presence or absence of hexamethonium.     

Interaction of permanently charged chlorpromazine and dopamine analogs with the striatal D-1 dopaminergic receptor

Although a structural feature common to all dopaminergic agonists and antagonists is a side-chain basic amino group, it is unclear whether this moiety binds to the D-1 dopamine (DA) receptor in the charged or uncharged form. To obtain information on this point, we synthesized permanently charged dimethylsulfonium and quaternary ammonium analogs of chlorpromazine and DA and determined whether these compounds can bind to the D-1 receptor by measuring their abilities to inhibit the binding of SCH 23390, a D-1 receptor antagonist. Chlorpromazine and the dimethylsulfonium and trimethylammonium analogs of chlorpromazine were found to inhibit the binding of [3H]SCH 22390, which was maximally inhibited to the same extent by all three compounds. In addition, inhibition curves for the compounds fit a one-site binding model, indicating binding to a single class of sites. However, while the permanently charged chlorpromazine analogs were able to inhibit [3H]SCH-23390 binding, they were considerably less potent than chlorpromazine. DA and dimethyl DA were also able to inhibit [3H]SCH 23390 binding. However, the permanently charged dimethylsulfonium and trimethylammonium analogs of DA were ineffective in inhibiting [3H]SCH 23390 binding. In addition, the permanently uncharged methylsulfide analog did not inhibit binding. These studies show that permanently charged analogs of chlorpromazine can bind to the striatal D-1 receptor, which is consistent with an anionic recognition site on the D-1 receptor that interacts with antagonists in the cationic form. In addition, it appears that a nitrogen atom is not required for binding to the D-1 receptor, since the sulfonium analog of chlorpromazine bound to the receptor to the same extent as chlorpromazine. However, since the permanently charged or uncharged analogs of DA did not bind to the D-1 receptor, it is still unclear as to whether the charged form of a dopaminergic agonist can bind. The lower potency or ineffectiveness of the permanently charged analogs compared to the parent amines (chlorpromazine, DA, dimethyl DA) in binding to the D-1 receptor may reflect the inability of the permanently charged analogs to undergo hydrogen binding with the anionic site of the receptor.     

Synthesis of 1-methyl-5-(pyrazol-3- and -5-yl- and 1, 2, 4-triazol-3- and 5-yl)-1, 2, 3, 6-tetrahydropyridine derivatives and their evaluation as muscarinic receptor ligands

A series of 1-methyl-5-(pyrazol-3- and -5-yl- and 1, 2, 4-triazol-3- and 5-yl)-1, 2, 3, 6-tetrahydropyridine derivatives structurally related to arecoline were synthesized and evaluated on M(1), M(2), and M(3) muscarinic receptors using [(3)H] pirenzepine and [(3)H] NMS as ligands. The binding affinity depended on the position and size of the substituents. The most interesting compounds were further evaluated in functional studies on isolated organs and in vivo for cholinergic side effects. Compounds 5 l and 6 i good M(1) and M(3) antagonistic properties in vitro and were devoid of cholinergic side effects in vivo.     

Beta 1-selective adrenoceptor antagonists: examples of the 2-[4-[3-(substituted-amino)-2-hydroxypropoxy]phenyl]imidazole class

A series of 2-[4-[3-(substituted-amino)-2-hydroxypropoxy]phenyl]imidazoles is described. The compounds were investigated in vitro for beta-adrenoceptor antagonism, and several examples were found to be selective for the beta 1-adrenoceptor. The structure--activity relationship exhibited by this series of compounds is discussed. (S)-2-[p-[3-[[2-(3,4-dimethoxyphenyl)ethyl]amino]-2-hydroxypropoxy]phenyl]-4-(2 -thienyl)imidazole [(S)-13] was over 100 times more selective than atenolol for the beta 1-adrenergic receptor and has been selected for in-depth studies.     

Urea and 2-imidazolidone derivatives of the muscarinic agents oxotremorine and N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide.

Some urea and 2-imidazolidone analogues of the muscarinic agents oxotremorine (1) and N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide [10; BM-5] have been synthesized and assayed for muscarinic and antimuscarinic activity on the isolated guinea pig ileum. The new compounds (15-24) were found to be muscarinic agonists, partial agonists, or antagonists. The compounds were also tested for in vitro receptor binding to homogenates of the rat cerebral cortex using the muscarinic antagonist [3H]-3-quinuclidinyl benzilate ([3H]QNB) as the ligand. They were found to be less potent than 1 in this assay. On the guinea pig ileum, the N-3-methyl substituted imidazolidone analogue 20 was the most potent agonist of the new compounds studied; 20 was 5-fold more potent in inducing contractions of the ileum and had 4-fold higher affinity for ileal muscarinic receptors than the 3-methyl substituted 2-pyrrolidone 6. However, the N-3-unsubstituted urea and imidazolidone derivatives 15 and 19 were several-fold less potent than the parent acetamide N-methyl-N-(4-pyrrolidino-2-butynyl)acetamide [9; UH-5] and 1, respectively. The urea analogue (16) of the partial muscarinic agonist 10 was devoid of intrinsic activity and displayed 3-fold lower affinity than 10 for ileal muscarinic receptors.     

Synthesis and DNA binding of [3-[2'-(2-acetamidoethyl)-2,4'-bithiazole-4-carboxamido]propyl[dimethylsulfonium chloride, a fragment of bleomycin A2

[3-[2'-(2-Acetamidoethyl)-2,4'-bithiazole-4-carboxamido]propyl]dimethylsulfonium chloride (1), the acetyl derivative of the cationic terminal dipeptide of bleomycin A2, has been synthesized and its binding to DNA and poly(dA-dT) has been studied by proton NMR and fluorescence spectroscopy. The spectral perturbations which occur upon binding of the compound to either nucleic acid indicate that that portion of bleomycin which binds to the nucleic acid can, for the most part, be mimicked by the fragment. The data are discussed in terms of the structure of the drug and the drug-nucleic acid complex.     

Synthesis and antiarrhythmic activity of novel 3-alkyl-1-[omega-[4-[(alkylsulfonyl)amino]phenyl]-omega- hydroxyalkyl]-1H-imidazolium salts and related compounds

Novel 3-alkyl-1-[omega-[4-[(alkylsulfonyl)amino]phenyl]-omega-hydroxyalkyl]-1H -imidazolium salts were synthesized and investigated for their class III electrophysiological activity on isolated canine cardiac Purkinje fibers and ventricular muscle tissue. Structure-activity relationships are discussed for a series of 25 compounds. Compound 3, 1-[2-hydroxy-2-[4-[(methylsulfonyl)amino]phenyl]ethyl]-3-methyl-1H- imidazolium chloride, prolonged the functional refractory period in anesthetized dogs when given intraduodenally and was also effective in preventing reentrant ventricular tachycardia induced by programmed electrical stimulation when administered intravenously in anesthetized dogs 24 h after an acute myocardial infarction. Both enantiomers of 3 were synthesized. No enantioselectivity was found in the electrophysiological effects of 3.     

Examination of a series of 8-[3-[bis(4-fluorophenyl)amino]propyl]-1-aryl-1,3,8- triazaspiro[4.5]decan-4-ones as potential antipsychotic agents

8-[3-[Bis(4-fluorophenyl)amino]propyl]-1-phenyl-1,3,8- triazaspiro[4.5]decan-4-one (3) and related compounds have been shown to have antipsychotic profiles in biochemical and behavioral pharmacological test models. The dose of 3 necessary to produce catalepsy in rats is much greater than that required for activity in behavioral tests predictive of antipsychotic efficacy, for example the suppression of high base line medial forebrain bundle self-stimulation in rats. This suggests that 3 would have a reduced propensity for neurological side effects. The effects of substitution on the 1-phenyl moiety and on the N-3 nitrogen atom of the triazaspirodecanone portion of 3 were examined. Results from this study suggest that behavioral activity is sensitive to substituents on the 1-phenyl moiety while substituents on the N-3 nitrogen are more generally tolerated. In both rats and squirrel monkeys compound 3 was found to have a similar separation between doses inhibiting Sidman avoidance activity and those causing catalepsy. However, in an extrapyramidal side effect (EPS) test model using haloperidol-sensitized cebus monkeys, 3 elicited signs of EPS at doses approximating those previously determined to be efficacious.     

Synthesis and antiallergic activity of 11-(aminoalkylidene)-6,11-dihydrodibenz[b,e]oxepin derivatives.

A new series of 11-substituted 6,11-dihydrodibenz[b,e]oxepin-2-carboxylic acid derivatives was synthesized and demonstrated to be orally active antiallergic agents. These compounds are structurally related to 1 (KW-4994), which we had reported previously to be a new antiallergic agent. Most compounds synthesized exhibited potent inhibitory effects on 48-h homologous passive cutaneous anaphylaxis (PCA) in rats and on IgG1-mediated bronchoconstriction in guinea pigs. Additionally, compounds possessing a terminal carboxyl group at the 2-position of the dibenz[b,e]oxepin ring system exhibited inhibitory effects on specific [3H]pyrilamine binding to guinea pig cerebellum histamine H1 receptors, whereas these demonstrated negligible effects on specific [3H]QNB binding to rat striatum muscarinic acetylcholine M1 receptors. Structure-activity relationship studies revealed that the following key elements were required for enhanced antiallergic activities: (1) a 3-(dimethylamino)propylidene group as the side chain at the 11-position, (2) a terminal carboxyl moiety at the 2-position, and (3) a dibenzoxepin ring system. Among the compounds synthesized, (Z)-11-[3-(dimethylamino)propylidene]-6,11-dihydrodibenz [b,e]oxepin-2-acetic acid hydrochloride (16) was selected for further evaluation. It had an ED50 value of 0.049 mg/kg po in the PCA test in rats and an ID50 value of 0.030 mg/kg po in inhibiting anaphylactic bronchoconstriction in guinea pigs. Furthermore, it had a Ki value of 16 +/- 0.35 nM for the histamine H1 receptor, while it exhibited negligible CNS side effects up to a dose of 600 mg/kg po. Compound 16 is now under clinical evaluation as KW-4679.     

Novel benzamides as selective and potent gastrokinetic agents. 2. Synthesis and structure-activity relationships of 4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2- morpholinyl]methyl] benzamide citrate (AS-4370) and related compounds

The title compounds (19-55) with a 4-substituted 2-(aminomethyl)morpholine group were prepared and evaluated for the gastrokinetic activity by determining their effect on gastric emptying of phenol red semisolid meal in rats. Introduction of chloro, fluoro, and trifluoromethyl groups to the benzyl group of the parent compounds 1a and 1b enhanced the activity. Among compounds tested, 4-amino-5-chloro-2-ethoxy-N-[[4-(4-fluorobenzyl)-2-morpholinyl] methyl] benzamide (23b) showed the most potent gastric emptying activity (effects on phenol red semisolid meal in rats and mice, and on resin pellets solid meal in rats). The gastrokinetic activity of 23b citrate (AS-4370) compared very favorably with that of cisapride and was higher than that of metoclopramide. In contrast to metoclopramide and cisapride, AS-4370 was free from dopamine D2 receptor antagonistic activity in both in vitro ([3H]spiperone binding) and in vivo (apomorphine-induced emesis in dogs) tests.     

Analogues of the muscarinic agent 2'-methylspiro[1-azabicyclo[2.2.2]octane-3,4'-[1,3]dioxolane]: synthesis and pharmacology.

A number of tetrahydrofuran analogues of 2'-methylspiro[1-azabicyclo[2.2.2]octane-3,4'-[1,3]dioxolane] (1) have been prepared with the aim to obtain information about the relative importance of each of the oxygens in 1 for efficacy and for selectivity. In addition, the dimethyl and desmethyl analogues of 1 were prepared. The new compounds were compared to cis- and trans-1 with regard to their ability to displace (-)-[3H]-3-quinuclidinyl benzilate ((-)-[3H]QNB) from muscarinic receptors in cerebral cortex, heart, parotid gland, and urinary bladder from guinea pigs. Functional studies were made on isolated guinea pig bladder and ileum. The new compounds exhibited both lower affinity and efficacy than cis-1. A conformational study was performed, and the effects of steric and electronic factors on the biological activity of the compounds are discussed.