Photoreactivity of diazines. Part III. Pyrimidines. Part XXXVIII. Photoamination of halogenopyrimidines

Abstract

The hitherto unknown u.v. induced amination of 4-X-6-phenylpyrimidines (V; X = Cl, Br, or I) to give 4-amino-6-phenylpyrimidine (VI), using liquid ammonia as solvent and reactant, is described. The reactivity order is found to be I > Br > Cl. Evidence is presented that the photoamination does not occur according to an S_N(ANRORC) or an S_N(AE) mechanism. Since an inhibitory effect of the radical scavenger di-t-butyl nitroxide is observed in the photoamination, a reaction pathway involving a radical as intermediate is postulated.