The present invention relates to bicyclic heterocycles of general formula ##STR00001## whereinR.sub.a to R.sub.c, A to E and X are defined as in claim 1, the tautomers, stereoisomers and salts thereof, particularly the physiologically acceptable salts thereof with inorganic or organic acids or bases which have valuable pharmacological properties, in particular an inhibitory effect on signal transduction mediated by tyrosine kinases, their use in the treatment of diseases, especially tumoral diseases and diseases of the lungs and airways, and the preparation thereof.