Serotonin 5-HT3 receptor partial activator

A method for preparing a serotonin 5-HT3 receptor partial activator which comprises

• mixing a compound represented by formula (2) with a pharmaceutically acceptable carrier, wherein formula (2) is:
• wherein R1to R4 are the same or different from one another and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted lower alkenyl group or a substituted or unsubstituted amino group, or two groups of R1 and R2 are linked together to form a benzene ring and R3 and R4 are hydrogen atoms, with the proviso that compounds in which all of R1 to R4 are hydrogen atoms are excluded;
• R5 represents a hydrogen atom;
• and m is an integer of 1 to 4, in which said lower alkyl group means a straight or branched C1-C4 alkyl group, said lower alkenyl group means a straight or branched C2-C4 alkenyl group, the substituent for said lower alkyl or lower alkenyl group is selected from the group consisting of a halogen atom, a hydroxyl group, a carbamoyl group, an amino group and a cyano group, the substituent for said amino group is selected from the group consisting of a straight or branched C1-C4 alkyl group, a straight or branched C1-C4 alkycarbonyl group, a straight or branched C2-C4 alkenyl group and a benzylidene group which may have a phenyl group, and said halogen atom is selected from the group consisting of fluorine, chlorine, bromine and iodine atoms.