Pyridine and pyrimidine derivatives

摘要

The present invention provides compounds of formula (I) wherein R¹, R², R³, R⁴ and X are as defined in the specification, and pharmaceutically acceptable salts thereof. The compounds are useful for the treatment and/or prophylaxis of diseases which are associated with DPP IV, such as diabetes, particularly non-insulin dependent diabetes mellitus, and impaired glucose tolerance.