The present invention related to compounds of formula (I): or a pharmaceutically acceptable salt, stereoisomer or tautomer thereof. Compounds of the present invention are inhibitors of histone deacetylase (HDAC) and are useful for treating cellular proliferative diseases, including cancer. Compounds of the present invention are useful for treating or preventing neurodegenerative diseases, schizophrenia and stroke among other diseases. ##STR00001##