Compounds, pharmaceuticals, kits, and methods are provided for use with DPP-IV and other S9 protease that comprise a compound comprising the formula: ##STR00001## wherein Q is selected from the group of CO, SO, SO.sub.2, or C.dbd.NR.sub.9; and R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined herein.