We initially investigated the conformational preference of the camphorsultam group relative to the TDO ring using the simplified TDO 31, featuring a C5-dimethylamine substituent (Fig. ). In the lowest energy conformer A, the C2 carbonyl group is oriented syn to the TDO sulfone, with the C=O bond bisecting the two S=O bonds. This arrangement allows for coplanarity between the carbonyl and the TDO ring, and maximises conjugation with the C5 amine nitrogen atom, with the sultam N-S bond positioned anti-to the carbonyl group to minimize steric clash with the TDO ring. To Information). The next highest energy minimum is Conformer B, which lies 0.7 kcal mol -1 higher in energy, in which the amide-sultam C-N bond is rotated ~180° relative to A. Conformer B benefits from enhanced nN(sultam)®p*CO interaction, but at a cost of increased steric clash between the camphorsultam carbocycle and the TDO ring, which also prohibits productive cycloaddition via this conformation (see Figure ).