Substituted 3-piperazinylalkyl-2,3-dihydro-4H-1,3-benzoxazin-4-ones and their use in therapy

A derivative of 2,3-dihydro-4-(piperazinylalkyl)-4H-1,3-benzoxazin-4-one of formula I ##STR23## in which the substituents are defined as follows:

• R.sub.1 and R.sub.2, which are identical or different, represent a hydrogen, a lower alkyl group containing 1 to 6 carbons, which is branched or unbranched;
• a lower alkyloxy group containing 1 to 4 carbons;
• a hydroxyl;
• a nitro;
• an amino which is unsubstituted or substituted by an acyl group or one or two alkyls, each independently containing 1 to 4 carbons;
• a sulfonylamino group;
• a halogen;
• R.sub.3 represents a hydrogen, an aliphatic group which is branched or unbranched and saturated or unsaturated, containing 1 to 5 carbons;
• R.sub.4 represents either:
• a phenyl group which can be unsubstituted or substituted by one or more identical or different radicals, chosen from amongst the following:
• a lower alkyl group containing 1 to 6 carbons, which is linear or branched,
• an alkyloxy group containing 1 to 6 carbons, which is linear or branched,
• a halogen,
• a trifluoromethyl,
• a nitro group,
• a hydroxy group,
• an amino which is unsubstituted or substituted by one or more alkyl groups, an acyl or a carboxylate, all three containing 1 to 4 carbons;
• a sulfonylamino group,
• a monocyclic heteroaryl group containing one or two nitrogen atoms selected from the class consisting of pyrridyl and pyrimidinyl groups;
• n can assume the values 2 to 6;
• as well as the therapeutically acceptable inorganic or organic salts of I;
• and also the racemates and the various enantiomers, or their mixtures when the compounds of the formula I contain an asymmetric carbon.