27877-69-6Relevant academic research and scientific papers
Carbon monoxide and hydrogen (syngas) as a C1-building block for selective catalytic methylation
Kaithal, Akash,H?lscher, Markus,Leitner, Walter
, p. 976 - 982 (2021)
A catalytic reaction using syngas (CO/H2) as feedstock for the selective β-methylation of alcohols was developed whereby carbon monoxide acts as a C1 source and hydrogen gas as a reducing agent. The overall transformation occurs through an intricate network of metal-catalyzed and base-mediated reactions. The molecular complex [Mn(CO)2Br[HN(C2H4PiPr2)2]]1comprising earth-abundant manganese acts as the metal component in the catalytic system enabling the generation of formaldehyde from syngas in a synthetically useful reaction. This new syngas conversion opens pathways to install methyl branches at sp3carbon centers utilizing renewable feedstocks and energy for the synthesis of biologically active compounds, fine chemicals, and advanced biofuels.
Manganese(I)-Catalyzed β-Methylation of Alcohols Using Methanol as C1 Source
Kaithal, Akash,van Bonn, Pit,H?lscher, Markus,Leitner, Walter
supporting information, p. 215 - 220 (2019/12/03)
Highly selective β-methylation of alcohols was achieved using an earth-abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)2Br[HN(C2H4PiPr2)2]] 1 ([HN(C2H4PiPr2)2]=MACHO-iPr). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were β-methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the β-position, opening a pathway to “biohybrid” molecules constructed entirely from non-fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal–ligand cooperation at the Mn-pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C?C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules.
Iron-Catalyzed β-Alkylation of Alcohols
Bettoni, Leó,Gaillard, Sylvain,Renaud, Jean-Luc
supporting information, p. 8404 - 8408 (2019/10/16)
β-Branched alkylated alcohols have been prepared in good yields using a double-hydrogen autotransfer strategy in the presence of our diaminocyclopentadienone iron tricarbonyl complex Fe1. The alkylation of some 2-arylethanol derivatives was successfully addressed with benzylic alcohols and methanol as alkylating reagents under mild conditions. Deuterium labeling experiments suggested that both alcohols (2-arylethanol and either methanol or benzyl alcohol) served as hydrogen donors in this cascade process.
Ruthenium(II)-Catalyzed β-Methylation of Alcohols using Methanol as C1 Source
Kaithal, Akash,Schmitz, Marc,H?lscher, Markus,Leitner, Walter
, p. 5287 - 5291 (2019/05/28)
Selective introduction of methyl branches into the carbon chains of alcohols can be achieved with low loadings of ruthenium precatalyst [RuH(CO)(BH4)(HN(C2H4PPh2)2)] (Ru-MACHO-BH) using methanol both as methylating reagent and as reaction medium. A wide range of structurally divers alcohols was β-methylated with excellent selectivity (>99 %) in fair to high yields (up to 94 %) under standard conditions, and turnover numbers up to 18,000 could be established. The overall reaction rate of the complex catalytic network appears to be governed by interconnection of the individual subcycles through availability of the reactive intermediates. The synthetic procedure opens pathways to important structural motifs following the Green Chemistry principles.
Synthesis of alcohols via a rhodium-catalyzed hydroformylation-reduction sequence using tertiary bidentate amine ligands
Cheung, Lawrence L. W.,Vasapollo, Giuseppe,Alper, Howard
supporting information; experimental part, p. 2019 - 2022 (2012/09/22)
The synthesis of alcohols from aromatic olefins is described using a rhodium-catalyzed hydroformylation-reduction sequence with the assistance of a tertiary diamine ligand. The alcohols are produced in excellent branched to linear ratios and in good to excellent isolated yields. In all cases no aldehyde product, from hydroformylation, or alkyl product, from olefin reduction, was detected. Copyright
