A novel compound of the formula (I): wherein R.sup.1 is alkoxycarbonyl or the like, R.sup.2 is alkyl or the like; R.sup.3 is hydrogen or the like; R.sup.4 is alkylene or the like; R.sup.5 is optionally substituted heterocyclic group; R.sup.6, R.sup.7, R.sup.8 and R.sup.9 are independently hydrogen; alkyl, alkoxy, or the like; R.sup.10 is optionally substituted aromatic ring, or the like; or a pharmaceutically acceptable salt thereof, which has an inhibitory activity against cholesteryl ester transfer protein (CETP).