The now corrected X-ray structure of (2R)-bornane-10,2-sultam ((À)-1a), as well as that of its already published N-crotonoyl derivative (À)-1d, were compared with those of the newly synthesized (2R)-fenchane-8,2-sultam (()-5a), as well as its N-crotonoyl derivative (À)-5d. Also the N-methyl-and N-acryloylfenchane-8,2-sultams (À)-5b,c were prepared, and both the reactivity and diastereoselectivity imparted by the new chiral auxiliary to N,N'-fumaroylbis[fenchane-8,2-sultam] (À)-5e were compared with those of (À)-1a by addition of cyclopenta-1,3-diene to (À)-5e, in various solvents and at different temperatures under TiCl 4 -mediated and uncatalyzed conditions. The determining influence of these factors is rationalized by the loss of the masked C 2 symmetry earlier attributed to camphor-derived sultams as well as transition-state dipolar stabilization by the solvent of the thermodynamically less stable syn-s-cis conformer.