A compound represented by the general formula (I-a): (I-a) [wherein R1a and R2a each means hydrogen, lower cycloalkyl, lower alkyl, etc.； R3a means hydrogen, lower cycloalkyl, lower alkyl, etc.； R4a and R5a each means lower alkyl, lower cycloalkyl, etc. or R4a and R5a are bonded to each other to form lower cycloalkylidene； and R6a 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.
