Bicykliske nitrogenheterocycler

Amino-substituted dihydropyrimido[4,5-d]pyrimidinones of the formula in which R1 represents hydrogen, lower alkyl, aryl, aryl-lower alkyl, heteroaryl, heteroaryl-lower alkyl, lower cycloalkyl or lower cycloalkyl-lower alkyl, R2 represents lower alkyl, aryl, aryl-lower alkyl, heteroaryl, heteroaryl-lower alkyl, lower cycloalkyl or lower cycloalkyl-lower alkyl, and R3 represents hydrogen, lower alkyl, aryl, aryl-lower alkyl, heteroaryl, heteroaryl-lower alkyl, lower cycloalkyl, lower cycloalkenyl or lower cycloalkyl-lower alkyl, and pharmaceutically acceptable salts thereof are protein kinase inhibitors. They can be used in the treatment or prophylaxis of inflammatory, immunological, oncological, bronchopulmonary, dermatological and cardiovascular disorders, in the treatment of asthma, central nervous system disorders or diabetic complications or for the prevention of graft rejection following transplant surgery.