Liberated reaction intermediates, nucleophilic trapping

Under similar conditions a-phenylthio esters 9 afford fluorides 10 (Scheme 3.5) [25]. The mechanism of this Pummerer-type reaction involves initial nucleophilic addition of the sulfur atom to the electrophilic iodine center to form the iodosulfonium salt 11. The liberated fluoride anion acts as a base with resultant formation of the classical Pummerer intermediate 12. Subsequent trapping of cation 12 with fluoride anion yields the final product 10 (Scheme 3.5) [25]. 

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