The Organocatalytic α‐Fluorination of Chiral γ‐Nitroaldehydes: the Challenge of Facing the Construction of a Quaternary Fluorinated Stereocenter

Chiral γ‐nitroaldehydes 1 are easily accessible by the organocatalytic Michael addition of aldehydes to nitroalkenes. In this paper, we report the organocatalytic fluorination of 1 with N ‐fluorobenzenesulfonimide (NFSI) leading to the highly stereoselective construction of a challenging quaternary fluorinated stereocenter at the α position of α,α‐dialkyl aldehydes. The reaction takes place via a chiral trisubstituted enamine, so far rather unexplored in the field of organocatalysis. Fluorinated products 3 are direct precursors of chiral monofluorinated 3,4‐polysubstituted pyrrolidines. Mechanistic details are discussed with the aid of computational results.