Carbostyril derivatives and process for preparing the same

Abstract

Carbostyril derivative represented by the formula (I): ##STR1## wherein R.sup.1 and R.sup.2, which may be the same or different, each represents a hydrogen atom, a cycloalkylcarbonyl group, a cycloalkylalkanoyl group, a benzoyl group, an alkanoyl group or a phenylalkylcarbonyl group; R.sup.4 represents a hydrogen atom or an alkyl group, R.sup.5 and R.sup.6, which may be the same or different, each represents a hydrogen atom, an alkyl group, a cycloalkyl group, or a phenylalkyl group, or R.sup.5 and R.sup.6 may, when taken together with the nitrogen atom to which they are attached, form a 5- or 6-membered substituted or unsubstituted heterocyclic ring containing 1 or 2 nitrogen or oxygen atoms as hetero atoms; and the ring A has a partial structure: ##STR2## wherein R.sup.3 represents a hydrogen atom, a cycloalkylcarbonyl group, a cycloalkylalkanoyl group, a benzoyl group, an alkanoyl group or a phenylalkylcarbonyl group, with the proviso that at least one of R.sup.1, R.sup.2 and R.sup.3 when R.sub.3 is present, or at least one of R.sub.1 and R.sub.2 when R.sub.3 is absent, represents a cycloalkylcarbonyl group, a cycloalkylalkanoyl group, a benzoyl group, an alkanoyl group or a phenylalkylcarbonyl group; the pharmaceutically acceptable acid addition salts of the above carbostyril compounds represented by the formula (I), and processes for preparing the above carbostyril compounds represented by the formula (I).