Enantioselective Oxazaborolidinium-Catalyzed Diels–Alder Reactions without CH⋅⋅⋅⋅O Hydrogen Bonding


  • Funding from the Australian Research Council (ARC) is gratefully acknowledged. M.N.P.-R. acknowledges computing time from the Australian Partnership for Advanced Computing (APAC) awarded under the Merit Allocation Scheme.


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Allcis-tems go! The first detailed computational investigations into the title reaction validate Corey's two pre-transition-state models and reveal a third Lewis acid coordination mode (see picture), which operates for esters having s-cis C[DOUBLE BOND]C[BOND]C[DOUBLE BOND]O groups. The new pre-transition-state model explains the unexpected enantioselectivity witnessed for several Diels–Alder reactions and does not involve a C[BOND]H⋅⋅⋅O hydrogen bond.