Purine derivatives for use as adenosin a2a receptor agonists

A compound of formula (I) or stereoisomers or pharmaceutically acceptable salts thereof, and their preparation and use as pharmaceuticalswherein R1, R 2 and R 3 are as defined herein. The compounds are useful for the treatment of a condition mediated by activation of the adenosine A2A receptor, especially inflammatory or obstructive airways diseases. Pharmaceutical compositions comprising a purine derivative as active ingredient and a process for the preparation of these compounds.