Lectka and coworkers have recently disclosed a catalytic, asymmetric alpha-fluorination of acid chlorides using NFSi (N-Fluorobenzenesulfonimide) as the source of electrophilic fluorine upon formation of the ketene enolate in the presence of benzoylquinidine (BQd-10 mol %), Hunig?s base, and (1,3-dppp)NiCl₂ or trans-(PPh₃)₂PdCl₂ (3 mol %). Upon quenching (a variety of nucleophiles can be employed, such as water, alcohols, amines, and thiols), the product is released in excellent yield and enantiopurity. Initial attempted development of the reaction was impeded by low yields; the addition of a metal co-catalyst resulted in higher yields. The mechanism proposed is based on previous work by Lectka and coworkers and relies on the formation of a key metal-bound zwitterionic ketene enolate species, which is followed by reaction with NFSi, and transacylation to form the observed products.

Paull, D.H.; Scerba, M.T.; Alden-Danforth, E.; Widger, L. R. Lectka, T. J. Am. Chem. Soc. ASAP.