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Reactivity of some 3‐substituted derivatives of 2,6‐dihalogenopyridines towards potassium amide in liquid ammonia [a]
Author(s) -
Streef J. W.,
Den Hertog H. J.,
Van Der Plas H. C.
Publication year - 1985
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.5570220411
Subject(s) - chemistry , liquid ammonia , amide , medicinal chemistry , reactivity (psychology) , derivative (finance) , ring (chemistry) , ammonia , potassium , stereochemistry , organic chemistry , medicine , alternative medicine , pathology , financial economics , economics
Reactions of 2,6‐dichloro‐3‐phenyl‐, 2,6‐dibromo‐3‐phenyl‐, 2,6‐dichloro‐3‐dimethylamino‐ and 2,6‐dibromo‐3‐dimethylaminopyridine with potassium amide in liquid ammonia were investigated. Whereas 2,6‐dichloro‐3‐phenylpyridine yields 4‐amino‐2‐benzylpyrimidine, from 2,6‐dibromo‐3‐phenylpyridine as a product of a novel ring fission 2‐amino‐l‐cyano‐l‐phenyl‐but‐l‐en‐3‐yne was isolated, together with 4‐amino‐6‐bromo‐3‐phenylpyridine and 2,6‐diamino‐3‐phenylpyridine. It was shown that neither 2‐amino‐6‐bromo‐3‐phenyl‐ nor 6‐amino‐2‐bromo‐3‐phenylpyridine are intermediates in the formation of the 2,6‐diamino derivative, as these bromo compounds are transformed in the basic medium into 1,3‐dicyano‐l‐phenylpropene. From both 2,6‐di‐chloro‐3‐dimethylamino‐ and 2,6‐dibromo‐3‐dimethylaminopyridine mixtures are obtained from which only 2‐amino‐l‐cyano‐l‐dimethylamino‐but‐l‐en‐3‐yne and 4‐amino‐6‐halogeno‐3‐dimethylaminopyridine were isolated. Mechanisms for the reactions studied are proposed, i.e. a S N (ANRORC) mechanism for the aminodebromination of 2,6‐dibromo‐3‐phenylpyridine into the corresponding 2,6‐diamino compound.