Isoxazolylalkylpiperazine derivatives having selective biological activity at dopamine D3 or D4 receptor, and preparation thereof

A method of treating schizophrenia comprising administering to a patient in need thereof a composition comprising an effective amount of at least one isoxazolylalkylpiperazine derivative represented by the following formula (1), in racemic form or as individual optical isomers or a pharmaceutically acceptable salt thereof,

• wherein R1 represents at least one substituent selected from the group consisting of an aryl group, a phenylmethyl group, a diphenylmethyl group and a 2-keto-1-benzimidazolinylgroup, wherein the substituent may have at least one further substituent selected from the group consisting of C1-C6 alkyl group, C1-C6 alkoxy group and a fluorine atom, a chlorine atom and a trifluoromethyl group;
• R2 represents at least one substituent selected from the group consisting of an aryl group, a phenylvinyl group and a thiophene group, wherein the substituent may have at least one further substituent selected from the group consisting of a fluorine atom, a chlorine atom, a nitro group, a C1-C6 alkyl group, a C1-C6 alkoxy group and a phenoxy group;
• X represents CH or a nitrogen atom;
• and
• n represents 3 or 4.