The invention provides a series of C4-substituted oxazole compounds having an alpha keto side chain at the 2 position, for example, compounds of formula I. The compounds can inhibit fatty acid amide hydrolase and can be useful for treatment of malconditions modulated by fatty acid amide hydrolase. The invention further provides methods of making compounds of formula I, useful intermediates in the preparation of compounds of formula I, and methods of using compounds of formula 1 and compositions thereof.