A method of treating a Hsp70-responsive disorder in a subject includes administering to the subject an effective amount of a compound represented by Structural Formula I, or a pharmaceutically acceptable salt or solvate thereof. Y is a covalent bond or an optionally substituted straight chained hydrocarbyl group, or, Y, taken together with both >C═Z groups to which it is bonded, is an optionally substituted aromatic group.R1-R4 are independently —H, an optionally substituted aliphatic group, an optionally substituted aryl group, or R1 and R3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R2 and R4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring.R7-R8 are independently —H, an optionally substituted aliphatic group, or an optionally substituted aryl group.Z is O or S.