Abstract:Dehydrogenative decarbonylation of a primary alcohol involves the release of both dihydrogen and carbon monoxide to afford the by one carbon unit shorter product. The transformation has now been achieved with a ruthenium‐catalyzed protocol by using the complex Ru(COD)Cl2 and the hindered monodentate ligand P(o‐tolyl)3 in refluxing p‐cymene. The reaction can be applied to both benzylic and long‐chain linear aliphatic alcohols. The intermediate aldehyde can be observed during the transformation, which is therefo… Show more
“…11,39 However, a coupled acceptorless dehydrogenative decarbonylation has not yet been applied for lignin valorisation. For this, we were inspired by the works of the group of Madsen and Sadow [40][41][42] who achieved acceptorless dehydrogenative decarbonylation reactions on a variety of primary alcohols by using iridium or rhodium-based homogeneous catalysts, importantly in conjunction with the release of valuable syngas (Fig. 2b).…”
Iridium catalysed acceptorless dehydrogenative decarbonylation of organosolv lignin is exemplified for the combined lignin defunctionalisation and liberation of synthesis gas.
“…11,39 However, a coupled acceptorless dehydrogenative decarbonylation has not yet been applied for lignin valorisation. For this, we were inspired by the works of the group of Madsen and Sadow [40][41][42] who achieved acceptorless dehydrogenative decarbonylation reactions on a variety of primary alcohols by using iridium or rhodium-based homogeneous catalysts, importantly in conjunction with the release of valuable syngas (Fig. 2b).…”
Iridium catalysed acceptorless dehydrogenative decarbonylation of organosolv lignin is exemplified for the combined lignin defunctionalisation and liberation of synthesis gas.
“…Using 1 H- 31 P HMBC NMR (see Supplementary Figures 6 – 13 ) we were able to assign the hydride triplet of triplets to two multiplets in the 31 P{ 1 H} NMR spectrum (at δ P = 34.8 ppm and δ P = 58.4 ppm; see SI), which is consistent with the structure of [Ru(H) 2 (PPh 3 ) 4 ] 64 . We tentatively assign the broad singlet at δ H = −12.5 ppm to [Ru(H) 2 (PPh 3 ) 3 ], which is corroborated by the appearance of a broad signal at δ P = 58 ppm in the 31 P{ 1 H} NMR spectrum 65 . [Ru(H) 2 (PPh 3 ) 3 ] would be in equilibrium with [Ru(H) 2 (PPh 3 ) 4 ] via association/dissociation of a PPh 3 ligand.…”
Section: Discussionmentioning
confidence: 65%
“…Ru(H) 2 (PPh 3 ) 3 can further react via alcohol decarbonylation to form the carbonyl-containing complex [RuHCl(CO)(PPh 3 ) 2 (Y)]. While methanol is not present under our reaction conditions for reductive amination, it is known that RuCl 2 (PPh 3 ) 3 can also enable the decarbonylation of benzyl alcohols and aldehydes 65 , which constitute a majority of our substrates. Fig.…”
The production of primary benzylic and aliphatic amines, which represent essential feedstocks and key intermediates for valuable chemicals, life science molecules and materials, is of central importance. Here, we report the synthesis of this class of amines starting from carbonyl compounds and ammonia by Ru-catalyzed reductive amination using H2. Key to success for this synthesis is the use of a simple RuCl2(PPh3)3 catalyst that empowers the synthesis of >90 various linear and branched benzylic, heterocyclic, and aliphatic amines under industrially viable and scalable conditions. Applying this catalyst, −NH2 moiety has been introduced in functionalized and structurally diverse compounds, steroid derivatives and pharmaceuticals. Noteworthy, the synthetic utility of this Ru-catalyzed amination protocol has been demonstrated by upscaling the reactions up to 10 gram-scale syntheses. Furthermore, in situ NMR studies were performed for the identification of active catalytic species. Based on these studies a mechanism for Ru-catalyzed reductive amination is proposed.
“…Madsen et al. described that Ru [6] and Ir [7] catalyst complexes possessing phosphine ligands showed DHM activity for aliphatic and aromatic primary alcohols. Although these catalysts are active, they present serious drawbacks with respect to recovery and reuse of the catalyst, and require additives or poisonous phosphine ligands, which severely restrict their industrial application.…”
The dehydroxymethylation of primary alcohols is a promising strategy to transform biomass‐derived oxygenates into hydrocarbon fuels. In this study, a novel, highly efficient, and reusable heterogeneous catalyst system was established for the H2‐free dehydroxymethylation of primary alcohol using cerium oxide‐supported palladium nanoparticles (Pd/CeO2). A wide range of aliphatic and aromatic alcohols including biomass‐derived alcohols were converted into the corresponding one‐carbon shorter hydrocarbons in high yields in the absence of any additives, accompanied by the production of H2 and CO. Pd/CeO2 was easily recovered from the reaction mixture and reused, retaining its high activity, thus, providing a simple and sustainable methodology to produce hydrocarbon fuels from biomass‐derived oxygenates.
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