Oil treatment of 4-phenylpyrimidine with potassium amide in liquid ammonia, a mixture of 6-amino-4-phenylpyrirnidine and 2-amino-4-phenylpyrimidine is obtained. It was proven that in the formation of the 2-amino compound the pyrimidine ring is opened but that in the formation of the 6-amino compound no ring opening is involved, 1H and 13C NMR spectroscopy gave evidence for formation of two σ adducts between the amide ion and 4-phenylpyrimidine, i.e., the 6-amino-1(or 3),6-dihydropyrimidinide ion and the 2-amino-1(or 3),2-dihydropyrimidinide ion. © 1979, American Chemical Society. All rights reserved.