PROBLEM TO BE SOLVED: To provide a therapeutic and/or preventive agent of neoplastic diseases.SOLUTION: This agent is a compound expressed by formula (I). In formula, R1 to R6 each represents a specific substituent group.COPYRIGHT: (C)2013,JPO&INPIT【課題】腫瘍性疾患の治療又は/及び予防剤の提供。【解決手段】次式(I)で表される化合物。[式(I)中、R1~R6は、特定の置換基を示す。]【選択図】なし