Compounds of formula I ##STR00001## in free or salt form, wherein R.sup.1, R.sup.2 and R.sup.3 have the meanings as indicated in the specification, are useful for treating conditions mediated by of phosphodiesterase type 4 or the down-regulation or inhibition of TNF-.alpha. release, particularly obstructive or inflammatory airways diseases. Pharmaceutical compositions that contain the compounds and processes for preparing the compounds are also described.