Herein, we present a fast, efficient and general one-pot method for the synthesis of ¹¹C-labelled compounds via the Negishi cross-coupling reaction. Our approach, based on the in situ formation of [¹¹C]CH₃ZnI and subsequent reaction with aryl halides or triflates, has proven efficient to synthesize [¹¹C]thymidine, a biologically relevant compound with potential applications as a proliferation marker. Theoretical calculations have shown irreversible formation of a tetracoordinated nucleophilic ¹¹C–Zn(II) reagent and electronic requirements for an efficient Negishi coupling.