Ruthenium-Catalyzed Regioselective C7–H Arylation of 2-(Het)aryl[1,2,4]triazolo[1,5-a]pyrimidines with Aryl Halides

Abstract

Unusual direction of the C–H arylation of 2-(het)aryl[1,2,4]triazolo[1,5-a]pyrimidines with (het)aryl halides under catalysis by ruthenium(II) complexes has been revealed. The reaction involved activation of the C⁷–H bond rather than the C^α–H bond of the (het)aryl substituent at C² of the triazolopyrimidine core. The arylation of 2-substituted [1,2,4]triazolo[1,5-a]pyrimidines with (het)aryl bromides afforded a series of 7-(het)aryl derivatives in good yields.