The present invention relates to a compound represented by the following formula (1):wherein D1, A1, D2, R1, D3, and R2 each have the same meaning as defined in the present specification or a salt thereof. The compound represented by the formula (1) or a salt thereof has an IKKβ inhibiting activity and the like and is useful for the prevention and/or treatment of IKKβ-associated diseases or symptoms and the like.