has been studied using DFT methods at the B3LYP/6-31G* level. The dimerization takes place through a process involving a Michaeladdition of a carbanion, obtained by deprotonation of 5g at the 3-position, to a second molecule of 5g, followed by an intramolecular Michaeladdition in the corresponding intermediate. The final protonation of the resulting anion accounts for the formation of the cis-fused