The present invention relates to a compound of formula (I), or a tautomer and/or a pharmaceutically acceptable salt thereof,wherein:R1 is alkyl, Cl, F or Br；R2 is H or F；R3 is selected from H and alkyl；R4 is selected from H and C(O)R6；R5 is H；or R4 and R5 are linked to form a heterocyclic group which is optionally substituted with one or more R10 groups；R6 is selected from R7, OR7 and NR8R9；R7, R8 and R9 are each independently selected from alkyl, cycloalkyl, aralkyl, cycloalkenyl, heterocyclyl and aryl, each of which is optionally substituted with one or more R10 groups；each R10 is independently selected from halogen, OH, CN, NO2, COO-alkyl, aralkyl, SO2-alkyl SO2-aryl, COOH, CO-alkyl, CO-aryl, NH2, NH-alkyl, N(alkyl)2, CF3, alkyl and alkoxy；X and Z are each independently CR11, and Y is selected from CR11 and N； and R11 is H or F；for use in treating a disorder associated with protein misfolding stress and in particular associated with accumulation of misfolded proteins.
