A compound of the formula: ##STR1## wherein R.sup.1 represents hydrogen or an optionally substituted hydrocarbon group; R.sup.2 represents an optionally substituted hydrocarbon group, an optionally substituted amino group or a substituted hydroxyl group; X represents an optionally halogenated lower alkylene group; Y represents a substituent; n represents an integer of 0 to 6; and m represents 0 or 1; or a salt thereof, a process for producing it, an intermediate for the production, and a pharmaceutical composition containing it are provided.