Quinoxaline derivatives, processes therefor, pharmaceutical compositions, and benzene derivatives

Claim 2

A quinoxaline derivative of the formula:- wherein R 1 and R 2 , which may be the same or different, stand for hydrogen, a halogen atom or a nitro group, or a halogenoalkyl, alkyl, alkoxy or alkylthio radical of not more than 6 carbon atoms, and R stands for hydrogen, a fluorine, chlorine or bromine atom, a methoxy radical, or a halogenoalkyl or alkyl radical of not more than 6 carbon atoms, provided that R 1 , R 2 and R 3 do not all stand for hydrogen at the same time, and wherein R 4 stands for hydrogen or an alkanoyl radical of not more than 6 carbon atoms.

Claim 3

A quinoxaline derivative of the formula I wherein R 1 and R 2 , which may be the same or different, stand for hydrogen, a halogen atom or a nitro group, or a halogenoalkyl, alkyl, alkoxy or alkylthio radical of not more than 6 carbon atoms, and R3 stands for hydrogen, a fluorine, chlorine or bromine atom, or a halogenoalkyl radical of not more than 6 carbon atoms, provided that R 1 , R 2 and R 3 do not all stand for hydrogen at the same time, and wherein R 4 stands for hydrogen or an alkanoyl radical of not more than 6 carbon atoms.

Claim 4

A quinoxaline derivative of the formula I wherein R 1 and R 2 , which may be the same or different, stand for hydrogen, a halogen atom or a nitro group, or a halogenoalkyl, alkyl, alkoxy or alkylthio radical of not more than 6 carbon atoms, and R3 stands for hydrogen, a fluorine, chlorine or bromine atom, or a halogenoalkyl radical of not more than 6 carbon atoms, provided that R 1 , R 2 and R 3 do not all stand for hydrogen at the same time, and wherein R 4 stands for hydrogen or an alkanoyl radical of not more than 6 carbon atoms.

Claim 5

A compound as claimed in claim 2 wherein R stands for a halogen atom linked to the 7-position of the quinoxaline nucleus, R 2 and R 4 stand for hydrogen, and R 3 stands for a fluorine, chlorine or bromine atom.

Claim 6

A compound as claimed in claim 3 which is selected from the group consisting of 2-amino-7-chloro-4-(4-chlorophenyl)quinoxalin-3(4H)-one-l-oxide, 2-amino-7-bromo-4-(4-chlorophenyl)quinoxalin-3(4H)-one-l-oxide and 2-amino-7-bromo-4-(4-bromophenyl)quinoxalin-3(4H)-one-I-oxide.

Claim 7

A process for the manufacture of a compound claimed in claim 1 in which R 4 stands for hydrogen, characterised in that a compound of the formula:- wherein R 1 , R 2 and R 3 have the meanings stated in claim 1 and X - stands for an anion, is reacted with a secondary amine in the presence of a C 1-5 - alkanol, initially at a relatively low temperature.

Claim 8

A process for the manufacture of a compound claimed in claim 1, characterised in that a compound of the formula:- wherein R 1 , R 2 , R 3 and R 4 have the meanings stated in claim 1, is reacted with a per-acid in the presence of an organic solvent.

Claim 9

A process for the manufacture of a compound claimed in claim 1 in which R 4 stands for an alkanoyl radical of not more than 6 carbon atoms, characterised in that a compound of the formula I, wherein R 4 stands for hydrogen and R1, Rand R 3 have the meanings stated in claim 1, is reacted with an acid anhydride derived from an alkanoic acid of not more than 6 carbon atoms.

Claim 10

A pharmaceutical composition comprising a compound of the formula I, wherein R 1 , R 2 , R 3 and R 4 have the meanings stated in claim 1, and an inert pharmaceutically-acceptable diluent or carrier.

Claim 11

9 . A pharmaceutical composition as claimed in claim 8 which contains, in addition to the compound of the formula I , at least one known neuroleptic agent.

Claim 12

A compound of the formula:- wherein R 1 , R 2 and R 3 have the meanings stated in claim 1 and X - has the meaning stated in claim 5.

Claim 13

A compound of the formula:- wherein R 1 , R 2 , R 3 and R 4 have the meanings stated in claim 1. What we claim is:- 1. A process for the manufacture of a quinoxaline derivative of the formula:- wherein R 1 and R 2 , which may be the same or different, stand for hydrogen, a halogen atom or a nitro group, or a halogenoalkyl, alkyl, alkoxy or alkylthio radical of not more than 6 carbon atoms, and R 3 stands for hydrogen, a fluorine, chlorine or bromine atom, a methoxy radical, or a halogenoalkyl or alkyl radical or not more than 6 carbon atoms, provided that R 1 , R 2 and R 3 do not all stand for hydrogen at the same time, and wherein R 4 stands for hydrogen, characterised in that a compound of the formula:- wherein R 1 , R 2 and R 3 have the meanings stated above and X stands for an anion, is reacted with a secondary amine in the presence of a C 1-5 -alkanol, initially at a relatively low temperature. 2. A process as claimed in claim 1, characterised in that X stands for a halide ion, the secondary amine is a saturated heterocyclic compound containing a 5-or 6-membered heterocyclic ring, part of which consists of the group C-NH-C, or a dialkylamine of not more than 12 carbon atoms, and the initial low temperature is in the range -70°C. to O°C. 3. A process for the manufacture of a compound of the formula I, wherein R 1 , R 2 and R 3 have the meanings stated in claim 1 and R 4 stands for hydrogen or an alkanoyl radical of not more than 6 carbon atoms, characterised in that a compound of the formula:- wherein R l , R 2 , R3 and R 4 have the meanings stated above, is reacted with a per-acid in the presence of an organic solvent. 4. A process as claimed in claim 3, characterised in that the per-acid is peracetic acid and the solvent is acetic acid, chloroform or methylene dichloride. 5. A process for the manufacture of a compound of the formula I, wherein R l , R 2 and R 3 have the meanings stated in claim 1 and R 4 stands for an alkanoyl radical of not more than 6 carbon atoms, characterised in that a compound of.the formula I, wherein R 1 ,R 2 and R 3 have the meanings stated above and R 4 stands for hydrogen, is reacted with an acid anhydride derived from an alkanoic acid of not more than 6 carbon atoms. 6 . A process as claimed in claim 5, characterised in that the acid anhydride is acetic anhydride, propionic anhydride or n-butyric anhydride. 7 . A process as claimed in claim 6, characterised in that the acid anhydride is acetic anhydride and the process is carried out in the presence of acetic acid.