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.