Understanding the Reactivity and Selectivity of Oxazaborolidium Ion‐Catalyzed Diels‐Alder Reactions Involving Cyclobutenones as Dienophiles

The poorly understood factors controlling the reactivity and selectivity (both stereo- and enantioselectivity) of catalyzed Diels-Alder reactions involving cyclobutenones as dienophiles have been analyzed in detail by means of Density Functional Theory calculations. To this end, the reactions with cyclopentadiene and furan as dienes and 3-(methoxycarbonyl)cyclobutenone catalyzed by Corey's chiral oxazaborolidium ion (COBI) have been selected and compared to their analogous uncatalyzed transformations. The combined Activation Strain Model of reactivity and Energy Decomposition Analysis methods have been used to quantitatively understand the acceleration and selectivity induced by the catalyst in this reaction.