Aspects of the amination of 4‐t‐butyl‐5‐halogenopyrimidines by potassium amide in liquid ammonia

Abstract The amination of 5‐bromo‐2,4‐di‐ t ‐butylpyrimidine ( 11b ), 5‐chloro‐2,4‐di‐ t ‐butylpyrimidine ( 11c ) and 4‐ t ‐butyl‐5‐chloropyrimidine ( 11a ) on treatment with potassium amide in liquid ammonia has been studied. 11b yields 6‐amino‐2,4‐di‐ t ‐butylpyrimidine ( 7b ) as major product. In contrast, 11c and 11a give 6‐amino‐5‐chloro‐2,4‐di‐ t ‐butylpyrimidine ( 12c ) and 6‐amino‐4‐ t ‐butyl‐5‐chloropyrimidine ( 12a ), respectively as main products, together with minor quantities of 7b and 6‐amino‐4‐ t ‐butylpyrimidine ( 7a ). Choice of halogen and accessibility of C(2) of the pyrimidine nucleus influence the mechanism of the amination. An S N (ANRORC) mechanism is not operative in any of the conversions described.