2-Benzoyl- and 2-(pyridylcarbonyl)-1-benzofuran-3-amines were prepared from 2-hydroxybenzonitrile and corresponding bromoethanone derivatives. 2-Benzoyl- and 2-(pyridylcarbonyl)-1-benzothiophene-3-amines were prepared analogously from 2-sulfanylbenzonitrile. 2-Benzoyl-1-benzofuran-3-amine treated with acetic anhydride or ethyl chloroformate provided the corresponding N-acetyl or N-ethoxycarbonyl derivatives. These N-activated compounds were alkylated with ethyl bromoacetate to provide ethyl N-acetyl-N-(2-benzoyl-1-benzofuran-3-yl)glycinate and ethyl N-(2-benzoyl-1-benzofuran-3-yl)-N-ethoxycarbonylglycinate, respectively. Their mild hydrolysis gave the corresponding glycine derivatives. Methylation of ethyl N-(2-benzoyl-1-benzofuran-3-yl)carbamate gave the corresponding N-methyl carbamate, which was hydrolyzed to N-methyl-(2-benzoyl-1-benzofuran-3-yl)amine. 2-Benzoyl-7-methoxy-1-benzofuran-3-amine and 2-(4-methoxybenzoyl)-1-benzofuran-3-amine were demethylated with boron tribromide to the corresponding hydroxy derivatives; their O-alkylation with ethyl bromoacetate than gave ethyl [(3-amino-2-benzoyl-1-benzofuran-7-yl)oxy]acetate and ethyl {4-[(3-amino-1-benzofuran-2-yl)carbonyl]phenoxy}acetate, respectively. The mild hydrolysis of these esters provided corresponding acids. Similarly, alkylation of the hydroxy derivatives with (dimethylamino)propyl chloride gave corresponding (dimethylamino)propoxy derivatives. 2-Hydroxybenzonitrile treated with 2-bromo-1-(2-, 3-, or 4-pyridyl)ethan-1-one provided the respective 2-(pyridylcarbonyl)-1-benzofuran-3-amine. Similar 2-(pyridylcarbonyl)-1-benzothiophene-3-amines were prepared analogously from 2-sulfanylbenzonitrile. 2-Benzoyl-3-(bromomethyl)-1-benzofuran treated with dimethylamine, 1-methylpiperazine, and sodium 1-methylpiperidine-4-thiolate gave the corresponding alkylation products. Several compounds were found to exhibit considerable analgesic activity.

3-Unsubstituted 1-benzofurans 1e and 1f, 3-methyl-1-benzofurans 1a-1d, and 3-amino-1-benzofurans 2a-2l, as well as 3-amino-1-benzothiophenes 3a, 3b and 3-aminoindoles 4a-4f, 11a, and 11b were prepared and tested as analgesics. The 3-amino-1-benzofurans 2 were prepared from the corresponding 2-hydroxybenzonitriles 5 and phenacyl bromides 6 via intermediates 7. Similar treatment of 2-sulfanylbenzonitrile (8) provided 3-amino-1-benzothiophenes 3. Appropriately substituted 2-aminobenzonitriles 9 then provided N-substituted 3-aminoindoles 4. 1-(Ethoxycarbonyl)indoles 4e and 4f were successfully deprotected giving indoles 11a and 11b, respectively.

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Molecular modification of anpirtoline (2a) is described. Several methods of preparation of 4-[(3-chlorophenyl)sulfanyl]-1-methylpiperidine (3a) and its demethylation led to the deazaanpirtoline (3c). Nucleophilic substitution of piperidine-4-thiole with 2-chloro-4-nitropyridine, 2,4-dichloro-6-methylpyridine, and 3,6-dichloropyridazine led to 2-chloro-4-(piperidin-4-ylsulfanyl)pyridine (6), 4-chloro-6-methyl-2-(piperidin-4-ylsulfanyl)pyridine (7), and 3-chloro-6-(piperidin-4-ylsulfanyl)pyridazine (8), respectively. 2-Chloro-6-(pyridin-4-ylsulfanyl)pyridine (10) and 4-[(2-chloropyridin-6-yl)sulfanyl]quinoline (11) were obtained from sodium 2-chloropyridine-6-thiolate. Homoanpirtoline analogs with methylene group inserted between the pyridine moiety and the sulfur atom (compound 12b) as well as between the sulfur atom and the piperidine ring (compound 13b) were also prepared.

New deaza derivatives of anpirtoline have been synthesized by three different methods. Their receptor binding profiles (5‐HT1A, 5‐HT1B) and analgesic activity (hot plate, acetic acid induced writhing) have been studied.