Origins of Transition State Stabilization

Proposed transition state for the asymmetric Diels-Alder reaction catalyzed by a Cu-box complex 

Transition state proposed for enantioselective Diels-Alder reactions catalyzed by a copper-bisoxazoline complex. The orientation of the diene and acrylate in this transition state resembles that in the transition state for an uncatalyzed [4+2] cycloaddition. Adapted from Evans, D. A. Barnes, D. M. Johnson, J. S. Leckta, T von Matt, R Miller, S. J. Murry, J. A. Norcross, R. D. Shaughnessy, E. A. Campos, K. R. J. Am. Chem. Soc. 1999,121,7582. 

Comparison of the reaction coordinates for an uncatalyzed and late-metal-catalyzed hydroboration of an alkene. 

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