Compounds of formula (I) are provided, wherein X is CH═CH, CH2O wherein the oxygen atom is bound to ring B, or OCH2 wherein the oxygen atom is bound to ring A； Y is hydrogen, straight or branched C1-C6 alkyl or a pharmaceutically acceptable inorganic cation； R1 is ethyl or cyclopropyl； and R2 and R3 are the same or different and are selected from F, Cl, Br, CF3 and OCF3. The compounds are useful for the treatment of autoimmune diseases, inflammatory diseases, organ transplant rejection, and malignant neoplasia. Pharmaceutical compositions containing the compounds, methods of using the compounds, and methods for preparing the compounds are also provided.
