Chiral Phosphoric Acid Catalyzed Transfer Hydrogenation of Ketimines

Significance

Akiyama and co-workers report an asymmetric phosphoric acid catalyzed synthesis of aromatic and heteroaromatic trifluorometh­ylated amines. To show the utility of this reaction, the authors carried out the synthesis of a perfluoroalkylated analogue of the bioactive compound NPS R-568. Benzothiazoline was used as a hydride source, and it shows stronger reactivity compared to the Hantzsch ester, which is commonly used as a transfer hydrogenation agent. Also, by employing a deuterated benzothiazoline in the reaction, the authors were able to enantioselectively incorporate deuterium into the products and at the same time provide support for a hydride mechanism in the transfer hydrogenation of ketimines with benzothiazoline.