Heteroarene formylations in DMF solution proceed in the presence of an amide base catalyst generated in situ from tetramethylammonium fluoride (TMAF) and tris(trimethylsilyl)amine (N(TMS) 3 ). The reaction proceeds at room temperature and has an operationally simple procedure. Various heteroarenes, including benzothiophene, thiophene, benzothiazole, oxazole, and indole derivatives, can be formylated with high functional group tolerance.