Patent ID: 6964975

Claim:
A compound represented by general formula [1] or salt thereof: wherein R1 is a halogen atom or lower alkyl optionally substituted by one or more substituents independently selected from: (I) alkyloxy, (II) alkylthio, (III) alkylamino, (IV) cyano, (V) nitro, (VI) cyclic amino, and (VII) a halogen atom; and R2 is an optionally substituted aryl or aromatic heterocycle; R3 represents a hydrogen atom, lower alkyl, or alkyl halide; R4 represents a group selected from (I) optionally substituted phenyl, aryl, or heterocycle, (II) substituted or nonsubstituted alkyl, and (III) substituted or nonsubstituted alkenyl, alternatively, R3 and R4 may form a five- to ten-membered cyclic structure together with a carbon atom to which they bind; and X represents an oxygen atom or a sulfur atom, provided that, when R3 is a hydrogen atom, then R4 represents a group other than methyl.