Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles (V): Conversion of some 2‐alkyl‐, 2‐aryl‐ and 2,5‐dialkyl‐4‐chloropyrimidines by potassium amide in liquid ammonia into 4‐alkyl derivatives of 2‐alkyl‐ or 2‐aryl‐<i>s</i>‐triazines

Abstract

Abstract Reactions of 2‐methyl‐, 2‐ethyl‐, 2‐phenyl‐, 2,5‐ and 2,6‐dimethyl‐4‐chloropyrimidine with potassium amide in liquid ammonia have been investigated. Together with aminations leading to the formation of 4‐amino compounds, conversions involving a ring transformation were found to occur. The latter process occurred in aminations of the three first‐mentioned substances, 2,4‐dimethyl‐, 2‐ethyl‐4‐methyl‐ and 4‐methyl‐2‐phenyl‐ s ‐triazine respectively being formed. Also from 4‐chloro‐2,5‐dimethylpyrimidine a s ‐triazine derivative, 4‐ethyl‐2‐methyl‐ s ‐triazine, was obtained. The last‐mentioned reaction indicates that in the ring transformation pyrimidynes are not involved and that the 5‐methyl group and the 5‐carbon atom of the pyrimidine ring contribute to the formation of the ethyl group in the reaction product. A mechanism for the ring transformation is proposed.