| abstract |
A compound of formula (I) or a pharmaceutically acceptable salt thereof: [wherein Ar is aryl or heteroaryl, optionally substituted; R1 is acyl; R2 is H or lower alkyl; R3 is H, and the like; R4 is H, and the like.] having the activity inhibiting DPP-IV activity. They are therefore useful in the treatment or prevention of conditions mediated by DPP-IV, such as Type 2 Diabete Mellitus. |