The invention provides compounds of formula I: and pharmaceutically acceptable salts thereof where R1 is a substituted or unsubstituted phenyl or a fused bicyclic comprising a substituted or unsubstituted phenyl. In addition, the present invention relates to methods of manufacturing and methods of using the compounds of formula I as well as pharmaceutical compositions containing such compounds. The compounds may be useful in treating diseases and conditions mediated by TRPA1, such as pain.