It is known that the reaction of DACs with aldehydes under the action of anhydrous GaCl 3 is an interesting method for the formation of substituted indenes and polycyclic lactones . Recently we have discovered a novel TaCl 5 -mediated transformation of DACs in the presence of two equivalents of aromatic aldehydes, which yields tetrahydronaphthalene derivatives (Scheme 2) . However, the range of substrates studied was quite limited. In this study, we report preliminary results on the study of the influence of factors of substituents in the ester group of DAC and aromatic aldehyde on the reaction outcome.