Iridium‐Catalyzed Selective Cross‐Coupling of Ethylene Glycol and Methanol to Lactic Acid

An atom‐economic approach that has an unprecedented high selectivity for the synthesis of lactic acid (LA) based on a catalytic dehydrogenative cross‐coupling by using inexpensive bulk ethylene glycol and methanol is described. This method relies on the synthesis and utilization of a novel iridium catalyst bearing three N‐heterocyclic carbenes derived from 1,3‐dimethylbenzimidazolium salts, and exhibits outstanding activity in the production of LA [turnover frequency (TOF) up to 3660 h−1] owing to an elegant metal–ligand cooperation. Good things come in threes: An unprecedented dehydrogenative C−C cross‐coupling with inexpensive bulk ethylene glycol and methanol has been developed by using a novel iridium catalyst bearing three N‐heterocyclic carbenes (NHCs). This procedure represents a highly selective and atom‐economic approach for the synthesis of lactic acid (TOF up to 3660 h−1). TOF=turnover frequency; TON=turnover number.