Phosphine-Catalyzed Intermolecular Acylfluorination of Alkynes via a P(V) Intermediate

We report on the phosphine-catalyzed intermolecular carbofluorination of alkynes using acyl fluorides as fluorinating reagents. This reaction promises to be a useful method for the synthesis of highly substituted monofluoroalkene derivatives, since acyl fluorides can be easily prepared from the corresponding carboxylic acid derivatives and the reaction proceeds under ambient conditions without the need for a transition-metal catalyst. Experimental and computational studies indicate that a five-coordinated fluorophosphorane is involved as the key intermediate in the fluorination step.