Enantioselective Protonation of Itaconimides with Thiols and the Rotational Kinetics of the Axially Chiral C-N Bond

Bicyclic guanidines are able to catalyze the protonation reactions of 2-phthalimidoacrylates with thiols in excellent yields and enantioselectivities. The protonation reaction of itaconimides with secondary phosphine oxides is also known. Herein, the tandem conjugate addition-enantioselective protonation of N-substituted itaconimides with thiols catalyzed by chiral bicyclic guanidine is investigated. The rotational barrier of the C-N axis of N-2-tert-butyl phenylitaconimide is also studied, both experimentally and computationally.