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An unusual thionyl chloride-promoted C-C bond formation to obtain 4,4'-bipyrazolones.

ABSTRACT: Dialkyl 5,5'-dioxo-4,4'-bipyrazole-4,4'-dicarboxylates are readily obtained by the reaction of 5-hydroxypyrazole-4-carboxylates in refluxing thionyl chloride. The obtained diesters can be transformed into the corresponding 4,4'-bipyrazoles via alkaline hydrolysis and subsequent decarboxylation. Detailed NMR spectroscopic investigations (¹H, ¹³C, ¹⁵N) were undertaken with all products prepared. Moreover, the structure of a representative 5,5'-dioxo-4,4'-bipyrazole-4,4'-dicarboxylate was confirmed by X-ray crystal structure analysis.

SUBMITTER: Eller GA

PROVIDER: S-EPMC6009192 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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An unusual thionyl chloride-promoted C-C bond formation to obtain 4,4'-bipyrazolones.

Eller Gernot A GA Vilkauskaitė Gytė G Šačkus Algirdas A Martynaitis Vytas V Mamuye Ashenafi Damtew AD Pace Vittorio V Holzer Wolfgang W

Beilstein journal of organic chemistry 20180604

Dialkyl 5,5'-dioxo-4,4'-bipyrazole-4,4'-dicarboxylates are readily obtained by the reaction of 5-hydroxypyrazole-4-carboxylates in refluxing thionyl chloride. The obtained diesters can be transformed into the corresponding 4,4'-bipyrazoles via alkaline hydrolysis and subsequent decarboxylation. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a representative 5,5'-dioxo-4,4'-bipyrazole ...[more]

PMID: 29977396

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