Process for preparing compounds of the formula where R 1, R 2, R 3, R 4, R 5, R 6 independently of one another represent hydrogen, methyl, ethyl or phenyl, R 8, R 9, R 10, R 11, R 12 independently of one another represent hydrogen, methyl, ethyl, fluoroalkyl having one or 2 carbon atoms and one to five fluorine atoms, halogen, methoxy, ethoxy, trifluoromethoxy or optionally methyl-, ethyl-, methoxy-, ethoxy- or halogen-substituted phenyl and n represents 0 or 1, characterized in that compounds of the formula where n and R 1 to R 6 have the meanings given above, are reacted in the presence of a base with compounds of the formula where R 8 to R 12 have the meanings given above, to give compounds of the formula where n, R 1 to R 6 and R 8 to R 12 have the meanings given above; the compounds of the formula are then esterified with compounds of the formula HO - (CR 1 R 2) n - CR 3 R 4 - CR 5 R 6 -OH, where n and R 1 to R 6 have the meanings given above and are, in the concrete individual case, identical to those in the compound of the general formula, in the presence of an acid as catalyst, to give the compounds of the formulae and (XVII) where n, R 1 to R 6 and R 8 to R 12 have the meanings given above and both n and the corresponding radicals R 1 to R 6 and R 8 to R 12 at the two positions of the compounds of the formulae or (XVII) are identical; the compounds of the formulae and (XVII) in which n, R 1 to R 6 and R 8 to R 12 have the meanings given above, are then converted by reaction with a strong base into the compounds of the formula where n, R 1 to R 6 and R 8 to R 12 have the meanings given above. R 1, R 2, R 3, R 4, R 5, R 6 independently of one another represent hydrogen, methyl, ethyl or phenyl, R 8, R 9, R 10, R 11, R 12 independently of one another represent hydrogen, methyl, ethyl, fluoroalkyl having one or 2 carbon atoms and one to five fluorine atoms, halogen, methoxy, ethoxy, trifluoromethoxy or optionally methyl-, ethyl-, methoxy-, ethoxy- or halogen-substituted phenyl and n represents 0 or 1, characterized in that compounds of the formula where n and R 1 to R 6 have the meanings given above, are reacted in the presence of a base with compounds of the formula where R 8 to R 12 have the meanings given above, to give compounds of the formula where n, R 1 to R 6 and R 8 to R 12 have the meanings given above; the compounds of the formula are then esterified with compounds of the formula HO - (CR 1 R 2) n - CR 3 R 4 - CR 5 R 6 -OH, where n and R 1 to R 6 have the meanings given above and are, in the concrete individual case, identical to those in the compound of the general formula, in the presence of an acid as catalyst, to give the compounds of the formulae and (XVII) where n, R 1 to R 6 and R 8 to R 12 have the meanings given above and both n and the corresponding radicals R 1 to R 6 and R 8 to R 12 at the two positions of the compounds of the formulae or (XVII) are identical; the compounds of the formulae and (XVII) in which n, R 1 to R 6 and R 8 to R 12 have the meanings given above, are then converted by reaction with a strong base into the compounds of the formula where n, R 1 to R 6 and R 8 to R 12 have the meanings given above.