AbstractAn efficient potassium persulfate mediated four component reaction for the construction of 5‐methyl pyrimidine derivatives has been established from readily available methyl ketones, amidine hydrochlorides and dimethyl sulfoxide. This transformation features dimethyl sulfoxide as a dual synthon, acting as the precursors of the methyl and methine units. Four new chemical bonds, involving two C−C and two C−N bonds were formed sequentially during the intermolecular oxidative annulation process. This synthetic method offers several advan...