| abstract |
A compound of the formula (I) or a pharmaceutically acceptable salt thereof: , [wherein X1 and X2 each is independently lower alkylene; X3 is =CH2, =CHF or =CF2; R1 is substituent, R2 and R3 each is independently H or lower alkyl; n is 0, 1, 2, 3 or 4.] having the activity inhibiting DPP-IV activity. They are therefore useful in the treatment of conditions mediated by DPP-IV, such as NIDDM. |