Dehydrogenative Esterification and Dehydrative Etherification by Coupling of Primary Alcohols Based on Catalytic Function Switching of an Iridium Complex

Esters and ethers are widely used in modern organic synthesis. In recent years, the synthesis of esters by the dehydrogenative coupling of primary alcohols has been reported to be an environmentally benign process. In this situations, if a single catalyst can be used for the synthesis of either esters or ethers by making slight alterations to the reaction conditions, the value of the synthetic methodology would increase. In this study, we successfully developed a new catalytic function switching system: not only dehydrogenative esterification but also dehydrative etherification under environmentally friendly conditions were accomplished by the employment of a single iridium catalyst based on catalytic function switching. Using benzyl alcohol as a starting material, the esterification product, benzyl benzoate, and the etherification product, dibenzyl ether, were obtained in 92 % and 89 % yields, respectively, by employing same iridium catalyst precursor bearing a dihydroxybipyridine ligand, under optimized conditions.