Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes

Kaithal, Akash; Hölscher, Markus; Leitner, Walter

doi:10.1002/anie.201808676

Cited by 121 publications

(62 citation statements)

References 43 publications

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“…Driven by the importance of enantiopure alcohols, [2] iron catalysts have been developed for the asymmetric hydrogenation of polar double bonds. [3][4][5][6][7] In contrast, manganese remained unexplored until 2016, when it was applied in the non-enantioselective hydrogenation of polar multiple bonds with H 2 [8][9][10][11][12][13][14][15] and, more rarely,u nder hydrogen-transfer conditions. [16][17][18] Similarly,e nantioselective Mn I catalysts for ketone hydrogenation with H 2 (Clarke: A, [19] Beller: B, [20] Han and Ding: C, [21] and ours: D [22] )a re more numerous than those for asymmetric transfer hydrogenation (E [23] and F [24] ; Figure 1).…”

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confidence: 99%

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

Passera

Mezzetti

2019

Angewandte Chemie

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The bis(carbonyl) manganese(I) complex [Mn(CO)2(1)]Br (2) with a chiral (NH)2P2 macrocyclic ligand (1) catalyzes the asymmetric transfer hydrogenation of polar double bonds with 2‐propanol as the hydrogen source. Ketones (43 substrates) are reduced to alcohols in high yields (up to >99 %) and with excellent enantioselectivities (90–99 % ee). A stereochemical model based on attractive CH–π interactions is proposed.

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confidence: 99%

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

Passera

Mezzetti

2019

Angewandte Chemie

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“…For a broad range of primary and secondary alcohols as substrates, the methyl group is introduced selectively in β ‐position providing the branched products in good to very high yields with water as the only byproduct (Scheme ). The synthetic methodology has been transferred and largely extended by the use of Mn(I)‐MACHO complex most recently . In this work we present a mechanistic analysis of this transformation with the original ruthenium catalyst based on experimentally and theoretically compiled data.…”

Section: Methodsmentioning

confidence: 99%

On the Mechanism of the Ruthenium‐catalyzed β‐methylation of Alcohols with Methanol

et al. 2020

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Selective β-methylation of alcohols with methanol has been recently described using a catalytic system comprising the ruthenium pincer complex [RuH(CO)(BH 4 )(HN(C 2 H 4 PPh 2 ) 2 )]-(Ru-MACHO-BH) 1 and alcoholate bases as co-catalysts. [1] Here we present a detailed mechanistic analysis for the mono-methylation of 1-phenyl-propane-1-ol 2 a as prototypical example. Several experimentally observed intermediates were localized as stable minima on the DFT-derived energy surface of the entire reaction network. The ruthenium complex [Ru(H) 2 (CO) (HN(C 2 H 4 PPh 2 ) 2 )] I was inferred as the active species catalyzing the de-hydrogenation/re-hydrogenation of substrates and intermediates ("hydrogen borrowing"). The hydrogen-bonded alcohol adduct of this complex was identified as the lowest lying intermediate (TDI). The CÀ C bond formation results from a base-catalyzed aldol reaction comprising the transition state with the highest energy (TDTS). Experimentally determined Gibbs free activation barriers of 26.1 kcal/mol and 26.0 kcal/mol in methanol and toluene as solvents, respectively, are reflected well by the computed energy span of the complex reaction network (29.2 kcal/mol).Catalytic methods for the introduction of methyl groups into organic substrates using methanol as C1 building block offer attractive synthetic pathways in line with the principles of Green Chemistry. In particular the synthesis of methyl branches in aliphatic carbon chains using methanol remains a significant challenge, however. [2] Most recently we showed that ruthenium pincer complex [RuH(CO)(BH 4 )(HN(C 2 H 4 PPh 2 ) 2 )]-(Ru-MACHO-BH) 1 is a versatile pre-catalyst for this reaction. [1] For a broad range of primary and secondary alcohols as substrates, the methyl group is introduced selectively in βposition providing the branched products in good to very high yields with water as the only byproduct (Scheme 1). The synthetic methodology has been transferred and largely extended by the use of Mn(I)-MACHO complex most recently. [3] In this work we present a mechanistic analysis of this transformation with the original ruthenium catalyst based on experimentally and theoretically compiled data.From the results of the synthetic studies, we postulated a working hypothesis for the catalytic process exemplified in Scheme 2 for the mono-methylation of 1-phenyl-propane-1-ol 2 a to 1-phenyl-2-methyl-propane-1-ol 3 a. The overall trans-formation involves five individual cycles A-E forming a complex reaction network. Initially both alcohol and methanol are dehydrogenated by the transition metal catalyst to form ketone and formaldehyde, respectively. [4] Subsequently, a base-catalyzed aldol condensation generates the CÀ C bond [5] and finally the unsaturated intermediate is step-wise re-hydrogenated at the ruthenium catalyst.The involvement of the de-and re-hydrogenation cycles is corroborated with a series of control experiments summarized in scheme 3. 1-phenyl-propane-1-ol 2 a reacts with 13 CH 3 OH to the mono-methylated product containing the 13 ...

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“…Heterogeneous catalysts able to convert cyclic organic carbonates with high selectivity have also been reported by other groups (Supporting Information, Table S1) . Very recently, three examples of homogeneous catalysts based on a non‐noble metal center (manganese) have been reported that transform organic carbonates into diols and methanol in high yields (Supporting Information, Table S1) …”

Section: Figurementioning

confidence: 99%

Indirect CO₂ Methanation: Hydrogenolysis of Cyclic Carbonates Catalyzed by Ru‐Modified Zeolite Produces Methane and Diols

et al. 2018

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We report a ruthenium‐modified zeolite which efficiently transforms propylene carbonate to propylene glycol and methane, under solvent‐free conditions. The catalyst achieved high product selectivity and no significant ageing effect was observed after multiple cycles. The resulting liquid product (water‐containing glycol) can be directly used as anti‐freeze solution and the gas phase can directly be used as an energy carrier in the form of H2‐enriched methane. This process efficiently bridges energy storage and an important chemical synthesis under sustainable (CO2 consuming) conditions.

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Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes

Cited by 121 publications

References 43 publications

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

On the Mechanism of the Ruthenium‐catalyzed β‐methylation of Alcohols with Methanol

Indirect CO₂ Methanation: Hydrogenolysis of Cyclic Carbonates Catalyzed by Ru‐Modified Zeolite Produces Methane and Diols

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Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes

Cited by 121 publications

References 43 publications

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

Retracted: The Manganese(I)‐Catalyzed Asymmetric Transfer Hydrogenation of Ketones: Disclosing the Macrocylic Privilege

On the Mechanism of the Ruthenium‐catalyzed β‐methylation of Alcohols with Methanol

Indirect CO2 Methanation: Hydrogenolysis of Cyclic Carbonates Catalyzed by Ru‐Modified Zeolite Produces Methane and Diols

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Indirect CO₂ Methanation: Hydrogenolysis of Cyclic Carbonates Catalyzed by Ru‐Modified Zeolite Produces Methane and Diols