Oxidative Transformations of Biosourced Alcohols Catalyzed by Earth‐Abundant Transition Metals

Abstract

The catalytic acceptorless dehydrogenative oxidation of biosourced alcohols into carboxylic acid salts was achieved using earth‐abundant Fe and Mn complexes that feature aliphatic PNP pincer ligands in good to excellent yields. The Fe derivatives were characterized by using 57Fe NMR spectroscopy. Mn pincer catalysts are catalytically more efficient than their Fe counterparts thanks to their robustness under basic conditions. Attempts to generate aldehydes from alcohols were not successful using the Fe and Mn species, but a commercially available Ru analogue achieves this transformation selectively under very mild conditions in the presence of a large excess of acetone as a hydrogen acceptor.

Manganese Complexes for (De)Hydrogenation Catalysis: A Comparison to Cobalt and Iron Catalysts

“…[98] Thed ehydrogenation of primary fatty alcohols to fatty acids using diverse Mn and Fe catalysts,b ased on Mn-1 and Fe-4,was described by Dumeignil/Gauvin and co-workers. [100] Thee xtraordinary long-term stability of Mn-1 is particularly impressive and there is no report which describes an early similarly stable homogeneous 3d metal catalyst, including iron. Theobserved TONs for Mn and Fe are in the same order of magnitude.…”

“…The dehydrogenation of primary fatty alcohols to fatty acids using diverse Mn and Fe catalysts, based on Mn‐1 and Fe‐4 , was described by Dumeignil/Gauvin and co‐workers …”

Recent Advances in Catalysis with Transition‐Metal Pincer Compounds

“…Then, the aldehyde reacts with an amine (or alcohol) to yield a hemiaminal (or hemiacetal), which is dehydrogenated to afford the amide (or ester) product. If the reaction is performed in water, the corresponding carboxylic acid is produced . This is one of the “greenest” protocols for the synthesis of amides, esters, and carboxylic acids, for which the only byproduct is molecular hydrogen.…”

Manganese-Catalyzed Dehydrogenative/Deoxygenative Coupling of Alcohols

“…18 Recently, Gauvin's group reported dehydrogenative oxidation of alcohols to carboxylic acid salts catalyzed by Fe or Mn complexes; however, only six examples were reported, and the catalytic system was water sensitive. 19 Therefore, an efficient and general atom-economic dehydrogenative coupling of alcohols with hydroxides to form carboxylates catalyzed by non-noble metal catalyst remained highly desirable. We recently developed a Mn-catalyzed dehydrogenative coupling of alcohols with hydroxides that can produce a wide range of carboxylic acids (46 examples) with high selectivity and efficiency (up to 96% yield and a TON of 14630).…”