Synthesis of pyrido[1,2‐ a ]benzimidazoles by cyclizative condensation of 2‐halopyridines and 1,2‐benzenediamines. Scope and mechanism of the reaction | Zendy

Sundberg Richard J. | Zendy; Ellis James E. | Zendy

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Synthesis of pyrido[1,2‐ a ]benzimidazoles by cyclizative condensation of 2‐halopyridines and 1,2‐benzenediamines. Scope and mechanism of the reaction

Author(s) -

Sundberg Richard J.,

Ellis James E.

Publication year - 1982

Publication title -

journal of heterocyclic chemistry

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.321

H-Index - 59

eISSN - 1943-5193

pISSN - 0022-152X

DOI - 10.1002/jhet.5570190326

Subject(s) - chemistry , pyridine , condensation , benzene , medicinal chemistry , imidazole , nucleophile , ring (chemistry) , nucleophilic substitution , nitro , scope (computer science) , stereochemistry , catalysis , organic chemistry , physics , alkyl , computer science , thermodynamics , programming language

The scope and mechanism of acid‐catalyzed cyclizative condensation of 2‐halopyridines with 1,2‐benzene‐diamines has been explored. The reaction requires a 2‐halopyridine which is activated toward nucleophilic substitution. Evidence in favor of a mechanism involving pyridine ring opening is presented. Of three substituted 1,2‐benzenediamines which were examined, the 4‐nitro compound gave a single cyclization product whereas 4‐chloro and 4‐methy 1‐derivatives gave isomeric mixtures. The structure of the product from 2‐chloro‐5‐nitropyridine and 4‐nitro‐1,2‐benzenediamine is shown to be 2,8‐dinitropyrido[1,2‐ a ]benz‐imidazole.

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