Catalytic, asymmetric alpha-fluorination of acid chlorides: dual metal-ketene enolate activation.

In this Communication, we disclose a catalytic, highly enantioselective (up to >99% ee) alpha-fluorination of acid chlorides to produce a variety of optically active carboxylic acid derivatives from readily accessible and commercially available starting materials. The reaction depends on dually activated ketene enolates generated from two discrete catalysts--a chiral nucleophile and an achiral transition metal complex working in tandem. The active, putative alpha-fluorobis(sulfonimide) intermediates readily transacylate in situ under mild conditions upon addition of a wide variety of nucleophiles, including complex natural products. As a consequence, the power of this method is witnessed by the broad range of alpha-fluorinated products that can be accessed efficiently depending on the work up conditions.