The present invention relates to therapeutically active and selective inhibitors of the enzyme DPP-IV, which are of formula I
wherein each n is one or two independently and R1, R2, R3, R6, R7, R9, and R10 are defined herein. The present invention also relates to pharmaceutical compositions comprising the compounds of formula I and the use of the compounds for treating diseases that are associated with proteins that are subject to inactivation by DPP-IV, such as type-2 diabetes and obesity.