PROBLEM TO BE SOLVED: To provide compounds for treating a proliferative disorder, such as cancer, by inducing Hsp70 production in cells and increasing the concentration of Hsp70 in the cytoplasm and on the surface of cells.SOLUTION: There are provided compounds represented by the following formula (I) and associated compounds. In the formula, Rand Rare independently an optionally substituted alkyl, etc., Rand Rare independently -H, an optionally substituted alkyl, etc., Rand Rare independently -H, an optionally substituted alkyl, etc., and Ris a covalent bond, or a substituted or unsubstituted C1-C6 alkylene group.