A method is described for producing a compound having the formula (I) or an admixture comprising a compound having the formula (I), having the following steps: dissolving an indanone having the formula (II) in a solvent or in an admixture which contains a solvent, the solvent being selected from the group of solvents which form an azeotrope with water, converting the indanone having the formula (II) with an aromatic aldehyde having the formula (III) in the presence of at least one organic base, according to the drawing: where R1 and R2 independently of each other signify hydrogen or a branched or unbranched alkyl group having from 1 to 12 carbon atoms and where R3, R4, R5, R6, R7, R8, R9, R10 and R11 independently of each other signify hydrogen, hydroxy or a branched or unbranched alkyl or alkoxy group having from 1 to 12 carbon atoms and removing water formed from the reaction admixture during the conversion. An admixture comprising a compound of the formula (I) and other components is further described.