Piperazine compounds

DETAILED DESCRIPTION We claim: 1.
A compound of formula (I) ##STR16## wherein R.
sub.
1 represents --COR.
sub.
4, --CO.
sub.
2 R.
sub.
4 or --COCO.
sub.
2 R.
sub.
4 (where R.
sub.
4 represents a hydrogen atom or a C.
sub.
1-6 alkyl or c.
sub.
2-6 alkenyl group; R.
sub.
2 and R.
sub.
3 are the same or different and are C.
sub.
1-6 alkyl or C.
sub.
3-6 alkenyl; or --NR.
sub.
2 R.
sub.
3 forms a 5-membered (optionally containing an oxygen atom adjacent to the nitrogen) or 6-membered ring, which ring optionally contains one unit of unsaturation and which is unsubstituted or substituted by methylidene optionally substituted by a group selected from nitrile, phenyl, carboxyl, amido, C.
sub.
1-6 alkyl, phen(C.
sub.
1-6)alkyl, C.
sub.
1-6 hydroxyalkyl, C.
sub.
1-6 carboxyalkyl and C.
sub.
1-6 amidoalkyl, --COR.
sub.
5 (where R.
sub.
5 represents C.
sub.
1-6 alkyl, --OR.
sub.
6 or --NHR.
sub.
6 and R.
sub.
6 represents hydrogen, C.
sub.
1-6 alkyl, phenyl, or phen(C.
sub.
1-6)alkyl or .
dbd.
NOR.
sub.
7 (where R.
sub.
7 represents C.
sub.
1-6 alkyl); X represents a direct bond, --CH.
sub.
2 --or --CH.
sub.
2 O--; Ar represents a phenyl moity substituted by one or more groups or atoms selected from halogen atoms, C.
sub.
1-6 alkyl, --CF.
sub.
3 and NO.
sub.
2 groups, or by two substituents which form a second ring; or a physiologically acceptable salt thereof.
2.
A compound according to claim 1 wherein R.
sub.
1 represents --COR.
sub.
4.
3.
A compound according to claim 1 wherein R.
sub.
1 represents --CO.
sub.
2 R.
sub.
4.
4.
A compound according to claim 1 wherein --NR.
sub.
2 R.
sub.
3 represents a pyrrolidine ring.
5.
A compound according to claim 1 wherein X represents --CH.
sub.
2 -- and Ar represents halosubstituted phenyl.
6.
A compound according to claim 1 wherein R.
sub.
4 represents --CH.
sub.
3, --CH.
sub.
2 CH.
sub.
3, --CH.
dbd.
CH.
sub.
2, --OCH.
sub.
3 or --OCH.
sub.
2 CH.
sub.
3.
7.
A compound selected from 4-Acetyl-1-[(3,4-dichlorophenyl)acetyl]-2-(1-pyrrolidinylmethyl)piperazine; 1-[(3,4-Dichlorophenyl)acetyl]-4-(1-oxo-2-propenyl)-2-(1-pyrrolidinylmethyl )piperazine; 1-[(3,4-Dichlorophenyl)acetyl]-4-(1-oxopropyl)-2-(1-pyrrolidinylmethyl)pipe razine; 4-Acetyl-1-[(3,4-dichlorophenyl)acetyl]-2-(1,2,3,6-tetrahydro-1-pyridinylme thyl)piperazine; Ethyl 4-[(3,4-dichlorophenyl)acetyl]-3-(1-pyrrolidinylmethyl)-1-piperazinecarbox ylate; Methyl 4-[(3,4-dichlorophenyl)acetyl]-3-(1,2,3,6-tetrahydro-1-pyridinylmethyl)-1- piperazinecarboxylate; or a physiologically acceptable salt thereof