Provided is a compound of formula (I):
or a pharmaceutically acceptable salt thereof. Also provided is a method of activating the Nrf2 pathway, comprising contacting cells with a sufficient amount of a compound of formula (I) described herein. Also provided is a method of treating a neurodegenerative disease, comprising administering to a subject in need of treatment for the neurodegenerative disease an effective amount of a compound of formula (I) described herein.