Facile synthesis of 2,5,7-trisubstituted oxazolo[5,4-d]pyrimidines via copper-catalyzed intramolecular C–O bond formation

A novel and convenient synthesis of 2,5,7-trisubstituted oxazolo[5,4-d]pyrimidines was presented. The key step involved an intramolecular C–O cross-coupling of the ortho-halopyrimidine amide via a copper (I)-mediated cyclization reaction, which provided target trisubstituted oxazolopyrimidine in moderate to good yields.