A compound represented by general formula (I), a medicinally acceptable salt or ester thereof, and an antineoplastic containing the same as the active ingredient, wherein Ar , Ar , Ar and Ar represent each aryl or heteroaryl, A represents an optionally substituted hydrocarbon group; X and Y represent each oxygen, sulfur, carbonyl, -CHR - (R being hydrogen or lower alkyl) or -NR - (R being hydrogen or lower alkyl), or X and Y are combined together to represent vinylene or ethynylene; R , R , R , R and R represent each hydrogen, halogeno, hydroxy, lower alkyl or lower alkoxy; R and R represent each hydrogen, halogeno, hydroxy, amino, nitro, cyano, carboxy, lower alkoxycarbonyl, carbamoyl, lower alkylcarbamoyl, lower alkyl, lower hydroxyalkyl, lower fluoroalkyl or lower alkoxy; R represents lower alkyl; and R represents hydrogen or lower alkyl; provided when one of X and Y represents oxygen, sulfur or -NR -, the other of them represents carbonyl or -CHR -.