| abstract |
The present invention provides a compound useful as a novel antitumor agent targeting a CSC that is important in continuous proliferation of malignant tumor, metastasis and recurrence of cancer, and its resistance to an antitumor agent; a medicament comprising the compound as an active ingredient; a pharmaceutical composition; and an antitumor agent; as well as a method of treating cancer and/or a method of preventing cancer. The present invention provides compounds represented by formula (I) : or pharmaceutically acceptable salts thereof, wherein X is an oxygen atom or sulfur atom; R 1 is a hydrogen atom, an alkyl group, or the like; R 2 is a halogen atom or the like; R 3 is a hydrogen atom, an alkyl group, or the like; m is 0, 1, 2, 3, or 4; and n is 1, 2, 3, or 4 (with the proviso that the sum of m and n is 1, 2, 3, or 4). |