The present invention provides compounds of the formula wherein R1, R2, R3 and n have meaning as described in the specification, methods for their preparation, and pharmaceutical compositions containing them. The compounds of formula (I) are adenosine A2B receptor agonists and, thus, may be employed for the treatment of diseases in mammals that are mediated by the A2B receptor including, but not limited to, septic shock, cystic fibrosis, impotence, diarrhea, and cardiac diseases. Cardiac diseases include hyperplasia consequent to hypertension, arteriosclerosis, and heart attack. The present invention also provides methods for the induction of pharmacological stress to facilitate coronary imaging of areas of ischemia by employing compounds of formula (I). The compounds of formula (I) may be labeled, e.g., with radioactive isotopes, and therefore are useful in kinetic binding experiments.