Stereocontrolled Fluorobenzylation of Vinyl Sulfones and α,β-Unsaturated Esters Mediated by a Remote Sulfinyl Group. Synthesis of Functionalized Enantiomerically Pure Benzylic Fluorides

A sulfinyl group in an ortho position
confers
enough chemical and configurational stability to monofluorobenzylcarbanions
to evolve in a completely stereoselective way in their reactions with
β-substituted vinyl sulfones and α,β-unsaturated
esters. Reactions afford easily separable mixtures of two epimers
differing in the configuration of the center derived from the Michael
acceptor (up to 98% de). They can be easily converted into enantiomerically
pure γ-fluorinated γ-phenylsulfones and γ-phenylesters
bearing two chiral centers.