Phthalazinone derivatives

There are according to the invention compounds of the formula I in which A1 and A2 denote hydrogen, optionally substituted lower alkyl, lower alkenyl or lower alkynyl; heterocyclyl-lower alkyl, acyl, lower alkylsulphonyl or arylsulphonyl; or together denote optionally substituted lower alkylene; Ar1 and Ar2 denote aryl, heteroaryl or optionally substituted cycloalkyl; X stands for oxygen or sulphur; and in which Q denotes a bivalent radical of the formula which is bonded via its Y-carrying carbon atom to the Q-bonding carbon atom and via its RB-carrying nitrogen atom to the RA-carrying nitrogen atom in formula I, in which Y stands for oxygen or sulphur and RA and RB denote hydrogen, optionally substituted lower alkyl or acyl; or in which Q denotes a bivalent radical of the formula which is bonded by its carbon atom to the Q-bonding carbon atom and via its nitrogen atom to the RA-carrying nitrogen atom in formula I, where RA has the said meanings apart from acyl; salts thereof and tautomers thereof. These inhibit protein kinases, such as protein tyrosine kinases.