PMR‐studies on the formation of adducts between 4‐substituted‐5‐bromopyrimidines and potassium amide in liquid ammonia

PMR‐spectra of some 5‐bromo‐4‐R‐pyrimidines (R=Ph, But, OMe, PhMeN, MeNH, Me) in KNH2/liquid NH3 are described. Evidence is presented for the formation of stable σ‐adducts by attack of an amide ion on C6 of the pyrimidine ring in the cases of R=Ph, But, OMe, PhMeN. When the C4‐substituent contains an acidic hydrogen atom α to the aromatic nucleus (R=MeNH, Me), deprotonation occurs and in the case of R=Me also adduct formation has been observed.