A compound of formula (I), or stereoisomers or pharmaceutically acceptable salts thereof, or stereoisomers or pharmaceutically acceptable salts thereof, wherein A, U 1 , U 2 , R 1a , R 1b , R 2 and R 3 have the meanings as indicated in the specification, are useful for treating conditions mediated by activation of the adenosine A 2A receptor, especially inflammatory or obstructive airways diseases. Pharmaceutical compositions that contain the compounds and a process for preparing the compounds are also described.
