Provided is a compound of formula (I), or a pharmaceutically acceptable salt thereof. Also provided is a method of treating, prophylaxis, or amelioration of a disease, comprising administering to a subject in need of treatment for the disease an effective amount of a compound of formula (I) described herein. In one embodiment, the method is a neurodegenerative disease, such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, or Alzheimer's disease.
