Let ϕ be an analytic function in the unit disk D := (z C : z < 1) which has the form ϕ(z) = 1 + p1z + p2z2 + p3z3 + with p1 > 0, p2, p3 R. For given such ϕ, let ∗(ϕ), (ϕ) and (ϕ) denote the classes of standardly normalized analytic functions f in D which satisfy z f J(z) ≺ ϕ(z), 1 + z f JJ(z) ≺ ϕ(z) f J(z) ≺ ϕ(z), z ∈ D, f (z)f J(z) respectively, where ≺ means the usual subordination. In this paper, we find the sharp bounds of |a2a3 − a4|, where an := f (n)(0)/n!, n ∈ N, over classes S∗(ϕ), K(ϕ) and R(ϕ).