The compound of the formula (I): ##STR00001## wherein W is a group of the following formula (VIII) binding to any possible position on the Q: ##STR00002## Q is, together with W, a group of the formula: --C(W).dbd.C(R.sup.3A)--N(R.sup.3)--, etc.; R.sup.3A is H or optionally substituted lower alkyl; R.sup.4, R.sup.5, R.sup.6, and R.sup.7 are independently H or optionally substituted lower alkyl; R.sup.1 is optionally substituted lower alkyl, etc.; R.sup.2 is H, etc.; R.sup.3 is H, etc.; Ar is phenyl, etc., or a pharmaceutically acceptable salt thereof, where these compounds exhibiting .beta.3-adrenoceptor-stimulating activity and being useful as a medicament for treatment of obesity, etc.