| Popis: |
An enantioselective arlyation of diaryl ketimines with phenols is reported. The generation of new tetrasubstituted stereogenic center comprising two or more aryl substituents in an enantioselective fashion is a challenging task. The problem lies in the inherent difficulty for the catalyst to differentiate between two enantiotopic faces, since little separates two aryl rings. Reported methodologies for the synthesis of α-triphenylmethanamine structural motif mostly rely on chiral transition metal- catalyzed reactions. To the best of our knowledge, there are no reports on the organocatalytic protocols for the generation of chiral α-triphenylmethanamines. Herein, we report a chiral phosphoric acid- catalyzed arylation of diaryl ketimines with phenols. The success of this transformation lies in the in situ generation of the reactive diaryl ketiminium species from isoindolinone alcohols, making it susceptible for the reaction with phenols. A broad range of ketimines and phenols afforded isoindolinone derivatives comprising triphenyl-substituted quaternary center of chirality in high yields and enantioselectivities, as well as high regioselectivities (where applicable). Mechanism of stereochemical induction will also be discussed. |
