A general and efficient Mn-catalyzed acceptorless dehydrogenative coupling of alcohols with hydroxides into carboxylates

The direct oxidation of alcohols into carboxylic acids is an essential reaction for the synthesis of bulky and fine chemicals. Most current processes require the use of either strong and toxic oxidants or the presence of pressurized oxygen. Herein, we report a sustainable manganese-catalyzed acceptorless dehydrogenative coupling of alcohols with alkaline water to form carboxylates generating H-2 as the sole by-product. This is a general applicable and efficient non-noble metal catalyzed dehydrogenative transformation of alcohols into carboxylates. The reaction proceeded selectively in the presence of a well-defined manganese pincer complex at a very low catalyst loading. A wide range of carboxylic acids (46 examples) were synthesized with high yields and excellent functional group tolerance. Mechanistic studies including control experiments, NMR spectroscopy, and X-ray crystallography identified the resting state and key intermediates in the catalytic cycle.