Compounds represented by the general formula (I) or pharmacologically acceptable salts thereof: (I) wherein Ar<1> is phenyl or the like; Ar<2> is phenylene or the like; R<1> is C1-3 alkyl or the like; R<2> and R<3> are each C1-6 alkyl or the like; X is S- or the like; and p, q and r are each independently an integer of 0 to 2.
