The present invention provides compounds of formula I: which are useful as modulators of GPR6, pharmaceutical compositions thereof, methods for treatment of conditions associated with GPR6, processes for making the compounds and intermediates thereof.本發明提供了具有式I之化合物:其作為GPR6之調節劑係有用的,提供了其藥用組成物、用於治療與GPR6相關聯病症之方法、用於製備該等化合物和其中間體之方法。