A compound represented by the general formula (I-a): [wherein R 1a and R 2a each means hydrogen, lower cycloalkyl, lower alkyl, etc.； R 3a means hydrogen, lower cycloalkyl, lower alkyl, etc.； R 4a and R 5a each means lower alkyl, lower cycloalkyl, etc. or R 4a and R 5a are bonded to each other to form lower cycloalkylidene； and R 6a means lower alkyl, lower haloalkyl, etc.]. This compound functions as an LCE inhibitor and is useful as a therapeutic agent for various circulatory diseases, nervous diseases, metabolic diseases, reproductive diseases, digestive tract diseases, neoplasm, infectious diseases, etc.
