NHC-catalyzed one-pot oxidation and oxidative esterification of allylic alcohols using TEMPO: the effect of alcohol additives

A combination of N-heterocyclic carbene (NHC) catalysts and 2,2,6,6-tetramethylpiperidine- N -oxyl (TEMPO) was proposed for the synthesis of allylic esters from allylic alcohols. The yield of one-pot conversion of allylic alcohols to esters increased when hexafluoroisopropanol (HFIP) was used. The effect of HFIP in this tandem reaction was investigated by monitoring the reaction using gas chromatographic analysis. Control experiments using oxoammonium showed that the oxidative esterification occurred via a single-electron transfer mechanism.