Aromatization of 4-aryl(hetaryl)tetrahydroimidazo[4,5- c ]pyridine-6-carboxylic acids and their lithium salts by the action of dimethyl sulfoxide has been revealed for the first time. Heating of these compounds in DMSO for 5–7 h at 90–95°C leads to the formation of 4-aryl(hetaryl)imidazo[4,5- c ]pyridine derivatives as a result of dehydrogenation and decarboxylation. Heating of the corresponding lithium salts generated in situ (DMSO, 90–95°C, 3–5 h) affords difficultly accessible 4-aryl(hetaryl)imidazo[4,5- c ]pyridine-6-carboxylic acids.

A series of 4-amino-6-(hetaryl)pyridazin-3-ones were synthesized for screening purpose. The target compounds were obtained on heating hydrazine hydrate with 6-(hetaryl)pyridazin-3-ones, which had been prepared via the interaction ofo-diaminohetaryls with 3-pyridazine-6-carboxylic acid.

A series of 4-amino-6-(hetaryl)pyridazin-3-ones were synthesized for screening purposes. The target compounds were obtained on heating hydrazine hydrate with 6-(hetaryl)pyridazin-3-ones, which had been prepared via the reaction of o-diaminohetaryls with 3-pyridazine-6-carboxylic acid.

Chlorination and bromination of 2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-one and its N-methyl-substituted derivatives in acetic acid at 90–95°C leads to formation of the corresponding 5,6-dichloro(dibromo)-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones. Iodination of the same substrates with ICl under analogous conditions yields 6-iodo derivatives. Chlorination of 6-iodo-1,3-dimethyl-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-one is accompanied by replacement of the iodine atom by chlorine with formation of 5,6-dichloro-1,3-dimethyl-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-one. Bromination of 6-bromo- and 6-chloro-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones gives 5,6-dibromo- and 5-bromo-6-chloro-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones, respectively.

Halogenation of 2-unsubstituted and 2-methylimidazo[4,5-b]pyridines and their N-methyl derivatives with bromine and chlorine in acetic acid takes different pathways, depending on the acetic acid concentration. The bromination in 50% aqueous acetic acid gives only 6-bromoimidazo[4,5-b]pyridines; bromination and chlorination of 2-unsubstituted imidazo[4,5-b]pyridines in glacial acetic acid leads to 5,6-dibromo(dichloro)imidazo[4,5-b]pyridin-2-ones, and bromination of 2-methylimidazo[4,5-b]pyridines in glacial acetic acid involves both the pyridine ring and the 2-methyl group to afford the corresponding 6-bromo-2-tribromomethylimidazo[4,5-b]pyridines.

Nitration of 1-phenyl-4,5-dihydroimidazo- and -1,2,3-triazolo[4,5-c]pyridin-4-ones initially occurs at the para position of the phenyl ring, and the subsequent nitration yields the corresponding 7-nitro-1-(4-nitrophenyl) derivatives. Treatment of the latter with hydrazine hydrate leads to formation of 1-(4-aminophenyl)-7-methyl-4,5-dihydroimidazo- and -1,2,3-triazolo[4,5-d]pyridazin-4-ones.

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ChemInformVolume 34, Issue 48 Heterocyclic Compounds Synthesis of N5-(Arylcarbamoyl)methyl Derivatives of Spinaceamine and 2-Azaspinaceamine (IV). N. N. Smolyar, N. N. Smolyar Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this authorN. P. Izotova, N. P. Izotova Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this authorS. V. Gres'ko, S. V. Gres'ko Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this authorYu. M. Yutilov, Yu. M. Yutilov Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this author N. N. Smolyar, N. N. Smolyar Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this authorN. P. Izotova, N. P. Izotova Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this authorS. V. Gres'ko, S. V. Gres'ko Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this authorYu. M. Yutilov, Yu. M. Yutilov Inst. fiz.-org. khim. uglekhim. im. Litvinenko, Nats. Akad. nauk Ukr., Donetsk 340114, UkraineSearch for more papers by this author First published: 05 November 2003 https://doi.org/10.1002/chin.200348141Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume34, Issue48December 2, 2003 RelatedInformation

The properties of a series of polynitrogen heterocyclic compounds of different structure were investigated as thermostabilizers for polypropylene and polycaproamide. It was found that polyheterocyclic compounds containing a condensed heterocyclic nucleus (1,2,4-triazole, thiazole, thiodiazole) and sterically-hindered phenol residue are the most promising compounds investigated.

Substituted 2-aryl- and 2-hetarylimidazo[4,5-d]pyridazines were synthesized by oxidative cyclization in the presence of sulfur of 4,5-diamino-6-methylpyridazin-3-one with substituted arene(hetarene)carbaldehydes or heterocyclic compounds having an activated methyl group.