The present invention relates to a compound The instant invention relates to a compound of formulae (I A), (I B), (X A), (X B), (Y A) or (Y B),wherein R′ representsand R″ represents hydrogen, hydroxy, C1-C7alkoxy, C1-C8-alkanoyloxy, or R5R4N—CO—O—, where R4 and R5 independently are C1-C7alkyl or phenyl which is unsubstituted or substituted by a substitutent selected from C1-C7alkyl, C1-C7alkoxy, halogen and trifluoromethyl and where R4 additionally is hydrogen； or R4 and R5 together represent C3-C6alkylene；in free form or in form of a pharmaceutically acceptable acid addition salt.Compounds of formulae (I A), (I B), (X A), (X B), (Y A) or (Y B) inhibit DPP-IV (dipeptidyl-peptidase-IV) activity. They are therefore indicated for use as pharmaceuticals in inhibiting DPP-IV and in the treatment of conditions mediated by DPP-IV, such as non-insulin-dependent diabetes mellitus, arthritis, obesity, osteoporosis and further conditions of impaired glucose tolerance.
