The double halofluorination reaction of alkynes using trihaloisocyanuric acids and Olah's reagent

Abstract

A simple and efficient method to produce a CF2 group vicinal to a CX2 group (X = chlorine or bromine) through double halofluorination reaction of alkynes using trihaloisocyanuric acid as halogenating agent and Pyridine.(HF)x (Olah's reagent) as fluoride source is presented. The alkynes used were 1-hexyne, 3-hexyne, phenylacetylene, 1-phenyl-1-butyne, and diphenylacetylene, obtaining, mainly, the desired products in 30–88 % yields. Among the trihaloisocyanuric acids studied, the tribromoisocyanuric acid gave the best yields and the most selective reactions, while trichloroisocyanuric acid, although the most reactive, had less selectivity in the reactions studied, giving in some cases several by-products.