Cinchona-Based Primary Amine Catalyzed a Proximal Functionalization of Dienamines: Asymmetric α-Fluorination of α-Branched Enals

Fluorination of dienamines generated by alpha-branched enals and 6'-hydroxy-9-amino-9-deoxy-epi-quinidine (30 mol %) with NSFI show excellent alpha-regioselectivity to construct allylic fluorides containing a highly stereocontrolled quaternary fluorinated carbon (E/Z >= 20/1 and up to 93% enantiometric excess (ee)). By DFT calculation, the quinuclidine moiety of the catalyst was shown to function as a coordinating group to promote a reaction at the proximal alpha-position, and the nonclassical CH hydrogen bond plays an important role in the high enantioselectivity.