The free energy for the formation of the sandwich complex (∆G -see Fig. above), involving the aromatic additive, was determined for a variety of different cases.The results, compiled in Table , indicate that for many cases, such a stabilization would be substantially favourable.It may be argued that the additive could directly attack the catalyst and take part in protonation chemistry, without the reactants being involved, but this is unlikely. Previous computational investigations by Wang and co-workers have indicated that the direct attack of the naphthol additive on the catalyst (quinine-squaramide, in their case) was not favourable. Nevertheless,