5-Amino pyrimidine synthesis via azirine skeletal remodelling.

A mild, metal-free annulative coupling of azirine-2H-carbaldehydes with benzamidine hydrochlorides is reported for the efficient synthesis of substituted 5-amino pyrimidines. This transformation proceeds via a cascade of condensation, intramolecular cyclisation, strain-release-driven azirine ring-opening, and aromatisation. This step-economical strategy highlights the untapped potential of strained azirines as versatile synthons for the synthesis of biologically potent 2,4-arylpyrimidin-5-amines.