Strong and Confined Acids Control Five Stereogenic Centers in Catalytic Asymmetric Diels–Alder Reactions of Cyclohexadienones with Cyclopentadiene

We describe a highly enantioselective Diels–Alder reaction of cross‐conjugated cyclohexadienones with cyclopentadiene, in which five stereocenters are effectively controlled by a strongly acidic and confined imidodiphosphorimidate catalyst. Our approach provides tricyclic products in excellent stereoselectivity. We also report methods to convert the obtained products into useful intermediates and a computational study that aids in gaining deeper insight into the reaction mechanism and origin of stereoselectivity. A highly enantio‐ and diastereoselective Diels–Alder reaction of cross‐conjugated dienones containing electronically unbiased quaternary centers with cyclopentadiene has been developed. The chiral microenvironment and greater acidity of the imidodiphosphorimidate (IDPi) Brønsted acid motif control the desired outcome. The resulting cycloaddition adducts contain up to five stereogenic centers.