Catalytic enantioselective aza-Diels-Alder reactions of unactivated acyclic 1,3-dienes with aryl-, alkenyl-, and alkyl-substituted imines.

A catalytic enantioselective aza-Diels-Alder reaction of unactivated acyclic dienes with aryl-, alkenyl-, and alkyl-substituted imines is described. With 5-10 mol% loadings of a new Brønsted acid catalyst, the aza-Diels-Alder reaction of unactivated acyclic dienes proceeded to give the corresponding aza-Diels-Alder adducts in high yields (up to 98%) with excellent enantioselectivity (up to 98% ee). Preliminary DFT calculations suggest that the reaction proceeds through a chiral ion pair intermediate.