Disclosed is a compound represented by the general formula (1) or a salt thereof. The compound or a salt thereof has an inhibitory activity on IKK.beta. and is therefore useful as preventive and/or therapeutic agent for a disease associated with IKK.beta.. In the formula, R.sup.1 represents a hydrogen atom, a lower alkyl group, an aryl group, a hydroxy group, or the like; R.sup.2 represents a halogen atom, a lower alkyl group, a lower alkenyl group, a lower alkynyl group, or the like; and m represents 0, 1, 2, or the like. ##STR00001##