Alkylamination of pteridines by primary alkylamines ‐ potassium permanganate

Abstract

AbstractReaction of 7‐phenyl, 7‐p‐methoxyphenyl, 7‐t‐butyl‐ and 6,7‐diphenylpteridine with ethylamine and t‐butylamine in the presence of potassium permanganate leads to the introduction of the ethylamino or t‐butylamino group at C‐4 in the above‐mentioned pteridines. In the reaction of ethylamine/potassium permanganate besides the 4‐(ethylamino)pteridine derivatives 2‐amino‐3‐formytpyrazines are obtained as side‐products. In the reaction with t‐butylamine/potassium permanganate the corresponding pteridin‐4‐ones are obtained as by‐products. The 1H nmr spectroscopic studies have revealed that at room temperature ethylamine easily gives a σ‐adduct at C‐4, yielding a 4‐(ethylamino)‐3,4‐dihydropteridine derivative. t‐Butylamine, however, only gives with the pteridines addition at C‐4 at low temperature, i.e. at −40°. This adduct dissociates at room temperature. n‐Propylamine and n‐butylamine show the same behavior as ethylamine.