Influence of norbornanone substituents on both the Wagner–Meerwein skeletal rearrangements under sulfonation conditions and the diastereoselectivity of the corresponding N,N′-bis-fumaroyl sultams in uncatalyzed Diels–Alder cycloadditions to cyclopenta-1,3

The Wagner–Meerwein domino rearrangement of norbornanone skeletons, under sulfonation conditions, is strongly influenced by the absence of a gem-dimethyl moiety at C(7). As a result, sulfonation at C(10) is less efficient due to a divergent pathway in the intermediate double bond formation and/or isomerization. Furthermore, the absence of such a gem-dimethyl moiety in the corresponding norbornane[10,2]sultam derivatives, sterically influences the orientation of the SO(1) and SO(2) substituents, hence on the π-facial steric shielding of the thermodynamically more stable anti-s-cis N-alkenoyl dienophiles. As a consequence, their diastereoselective [4+2] cycloadditions to cyclopenta-1,3-diene, under nonchelating conditions, are not as efficient due to a less pseudo axial SO(1) and the consequent loss of pseudo C2-symmetry.