Nonsilyl Bicyclic Secondary Amine Catalysts for the Asymmetric Transfer Hydrogenation of α,β-Unsaturated Aldehydes

The first chiral synthesis of nonsilyl
bicyclic secondary amine
organocatalysts and their application to the asymmetric transfer hydrogenation
of α,β-unsaturated aldehydes are disclosed. A lower catalytic
loading (5 mol %) is demonstrated for the reduction of a wide range
of α,β-unsaturated aldehydes (up to 97% yield and up to
99% ee). The application of this scalable methodology
is showcased for the asymmetric synthesis of bioactive molecules such
as phenoxanol, citronellol, ramelteon, and terikalant.