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.

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