Patent ID: 7115751

Claim:
A method of producing indole derivative trimer of following formula (2): wherein R 1 to R 12 are substituents each independently selected from the group consisting of hydrogen, linear or branched alkyl group having 1 to 24 carbon atoms, linear or branched alkoxy group having 1 to 24 carbon atoms, linear or branched acyl group, having 2 to 24 carbon atoms, aldehyde group, carboxyl group, linear or branched carboxylate ester group having 2 to 24 carbon atoms, sulfonic group, linear or branched sulfonic ester group having 1 to 24 carbon atoms, cyano group, hydroxyl group, nitro group, amino group, amide group, and halogen group; X a− is at least one anion selected from the group of monovalent to tervalent anions consisting of chlorine ion, bromine ion, iodine ion, fluorine ion, nitrate ion, sulfate ion, hydrogen sulfate ion, phosphate ion, fluoroborate ion, perchiorate ion, thiocyanate ion, acetate ion, propionate ion, methane sulfonate ion, p-toluene sulfonate ion, trifluoroacetate ion, and trifluceomethane sulfonate ion; a is an integral number in the range from 1 to 3 indicating the ionic valence of the ion X; and m is a number in the range from 0 to 0.5, comprising: reacting at least one indole derivative (A) of following formula (1): wherein R 1 to R 4 are substituents each independently selected from the group of consisting of hydrogen, linear or branched alkyl group having 1 to 24 carbon atoms, linear or branched alkoxy group having 1 to 24 carbon atoms, linear or branched acyl group having 2 to 24 atoms, aldehyde group, carboxyl group, linear or branched carboxylic ester group, sulfonic group, linear or branched sulfonic ester group having 1 to 24 carbon atoms, cyano group, hydroxyl group, nitro group, amino group, amide group, and halogen group in a reaction mixture containing at least one oxidant (B) selected from the group consisting of ferric chloride anhydrate, ferric chloride hexahydrate, ferric nitrate hexahydrate, ferric sulfate n-hydrate, ferric sulfate ammonium dodecahydrate, ferric perchiorate n-hydarate cupric chloride, cupric tetrafluoroborate, ozone, and ammonium persulfate and at least one organic solvent (C).