simp_rw [← Complex.real_smul]
case refine_2
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
⊢ Function.HasTemperateGrowth fun x => cexp (↑(-x) * I)
case refine_2
E : Type u_1
inst✝¹ : NormedAddCommGroup E
inst✝ : NormedSpace ℝ E
⊢ Function.HasTemperateGrowth fun x => cexp (-x • I)