EWG assisted nucleophilic fluorination using PPHF: a strategy for the synthesis of 1,2,2-triaryl-2-fluoroethanones

The nucleophilic fluorination of 1,2,2-triaryl-2-hydroxyethanones by fluoride ion has been carried out using pyridinium poly(hydrogen fluoride) (PPHF) to give 1,2,2-triaryl-2-fluoroethanones in fairly good yield. The presence of electron withdrawing group (EWG), such as -COAr at the carbon bearing hydroxyl group facilitates such nucleophilic fluorination. The intermediacy of bridged oxiranyl ion and α-ketocarbenium ion has been proposed for the formation of various α-fluoroketones and benzofuran derivatives respectively.