Formation of sulfinate esters in the synthesis of triflates

Abstract

On standard treatment of sterically congested alcohols and phenols with triflic anhydride in the presence of amines, trifluoromethanesulfinyl esters were unexpectedly found. Depending on the reaction conditions and the structures of both hydroxy compound and base, esterified products (yields <5% to 99%) containing 0% to 89% (!) of sulfinates were obtained. The mechanisms of these reactions are discussed. The results of the present study indicate how to avoid unwanted sulfinate formation in triflate synthesis.