Heterogeneous Sodium‐Manganese Oxide Catalyzed Aerobic Oxidative Cleavage of 1,2‐Diols

Abstract

The aerobic oxidative cleavage of 1,2-diols using a heterogeneous catalyst only based on earth-abundant metals manganese and sodium is reported for the first time. This reusable catalyst cleaves a variety of substrates into aldehydes or ketones with high selectivity. The reaction requires small catalytic loadings and is performed under mild conditions using ambient pressure O or air as the oxidant while producing water as the only by-product. Mechanistic investigations reveal a monodentate, two-electron oxidative fragmentation process involving a Mn species. The eco-friendly, innocuous catalyst is compatible with a wide range of functional groups and conditions, making it highly competitive with classical reagents, such as periodic acid or lead tetraacetate, as a preferred method for activated 1,2-diols.

Oxidative Cleavage of Methyl 9,10‐Epoxystearate over WO3/MCM‐41 for Methyl 9‐Oxononanoate Production

“…a was basically completely consumed within 30 min, after which the contents of c and d increased while that of b decreased. It revealed that b was cracked into c and d …”

“…a was basically completely consumed within 30 min, after which the contents of c and d increased while that of b decreased. It revealed that b was cracked into c and d. [28,29] Finally, we proposed the reaction pathway which was divided into two steps. Epoxide a was first hydrolyzed to diols b which was then cleaved into c and d (Scheme 2).…”

Silver(I)‐Catalyzed Widely Applicable Aerobic 1,2‐Diol Oxidative Cleavage

“…Until now, no method has provided full substrate scope covering aliphatic, aromatic, terminal, internal, and cyclic 1,2‐diols for the catalytic aerobic oxidative cleavage of 1,2‐diols under atmospheric or low pressure and at mild temperature. Very recently, Escande, Anastas, and co‐workers reported an elegant sodium–manganese layered mixed oxide (Na–Mn LMO)‐catalyzed aerobic oxidative cleavage of 1,2‐diols into the corresponding aldehydes (Figure b) . Despite significant generality for benzylic and allylic diols, aliphatic (linear or cyclic) diols were inactive.…”

Silver(I)‐Catalyzed Widely Applicable Aerobic 1,2‐Diol Oxidative Cleavage

“…[6] Hence,t here have been many new catalysts and oxidants developed in attempts to overcome these limitations. [7] Nevertheless,t hey generally suffer from poor selectivity and adaptability.Until now,nomethod has provided full substrate scope covering aliphatic,a romatic,t erminal, internal, and cyclic 1,2-diols for the catalytic aerobic oxidative cleavage of 1,2-diols under atmospheric or low pressure and at mild temperature.V ery recently,E scande,A nastas,a nd co-workers reported an elegant sodium-manganese layered mixed oxide (Na-Mn LMO)-catalyzed aerobic oxidative cleavage of 1,2-diols into the corresponding aldehydes ( Figure 1b). [7a] Despite significant generality for benzylic and allylic diols, aliphatic (linear or cyclic) diols were inactive.T he cleavage also requires quite ah igh reaction temperature (100 8 8C) and only produces aldehyde products.A lthough the oxidative cleavage of certain 1,2-diols into both aldehydes and carboxylic acids has been described previously, [7o] acleavage method that offers both good selectivity and wide adaptability,and at the same time consumes anonhazardous and greener oxidant (such as aerobic oxygen) under mild conditions,isstill highly desirable but challenging to develop.…”

“…When the reaction time was shortened by half,t he product was obtained in 96 %y ield (92 %a fter purification;e ntry 5). We also examined more common silver salts,such as Ag 2 CO 3 ,asthe catalyst (entry 6), but inferior yields were observed even with ap rolonged reaction time.Control experiments indicated that the reaction was shut down when either the base,t he catalyst, or oxygen was absent (entries [7][8][9]. An experiment in the dark did not affect the result of the reaction, thus excluding the possible involvement of light (entry 10).…”