Reactions of carbon nucleophiles with 4‐phenyl‐ and 4‐tert‐butyl‐5‐halogenopyrimidines. On the occurrence of an SRN1 mechanism

Abstract

AbstractReaction of 5‐X‐4‐phenylpyrimidine (X = Br, Cl) with the enolate anions of acetone and acetophenone in liquid ammonia yields 5‐acetonyl‐ and 5‐phenacyl‐4‐phenylpyrimidine, respectively. It is shown that these reactions proceed via an SRN1 mechanism. Reaction of 5‐X‐4‐phenylpyrimidine (X = Br, Cl) with the enolate anion of pinacolone gives besides SRN1 substitution, addition of the anion to the N(1)‐C(6)‐azomethine bond. On treatment of 5‐X‐4‐tert‐butylpyrimidine with the enolate anions of acetone, acetophenone or pinacolone, substitution products are formed in very low yields. Addition of potassium to the liquid ammonia or irradiation with near ultraviolet light, however, increases the yields of 5‐substituted 4‐tert‐butylpyrimidine derivatives considerably.