Acid chlorides enantioselective fluorinations

Catalytic and highly enantioselective fluorination of acyl chlorides was reported by Lectka et al. where O-benzoyl quinidine (O-Bz-QD), is combined with a transition metal-based cocatalyst, (l,3-dppp)NiCl2 or trans-(PPh3)2PdCl2, to generate chiral ketene enolates from acyl chlorides, which are fluorinated with NFSI to produce ot-fluorinated carboxylic acid derivatives. These derivatives are then in situ reacted with different nucleophiles such as methanol, water or variety of amines affording a-fluoro esters, acids... 

Scheme 5.134 Lectka s enantioselective fluorination of acid chlorides 543 catalyzed by benzoylquinidine 545. "Trifunctional" reaction mechanism.

Leckta has developed a catalytic asymmetric a-fluorination of acid chlorides utilising a dual activation strategy. " Treatment of an acid chloride with both quinidine and either a Ni(ii) or Pd(ii) source in the presence of NFSI and Hunig s base resulted in the formation of an unactivated, a-fluorinated carbonyl which could be subsequently captured by a range of nucleophiles resulting in the formation of densely functionalised products with excellent enantioselectivity (Scheme 15.40). 

Scheme 15.40 Dual activation strategy for the enantioselective fluorination of acid chlorides.

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