Engineering a new-to-nature cascade for phosphate-dependent formate to formaldehyde conversion in vitro and in vivo.

Formate can be envisioned at the core of a carbon-neutral bioeconomy, where it is produced from CO by (electro-)chemical means and converted into value-added products by enzymatic cascades or engineered microbes. A key step in expanding synthetic formate assimilation is its thermodynamically challenging reduction to formaldehyde. Here, we develop a two-enzyme route in which formate is activated to formyl phosphate and subsequently reduced to formaldehyde.

Improved Itaconate Production with via Co-Metabolism of CO-Derived Formate.

In recent years, it was shown that itaconic acid can be produced from glucose with strains at up to maximum theoretical yield. The use of acetate and formate as co-feedstocks can boost the efficiency of itaconate production with Ustilaginaceae wild-type strains by reducing the glucose amount and thus the agricultural land required for the biotechnological production of this chemical. Metabolically engineered strains ( Δ Δ ↑P and Δ Δ P ↑P) were applied in itaconate production, obtaining a titer of 56.

A Self-Separating Multiphasic System for Catalytic Hydrogenation of CO and CO -Derivatives to Methanol.

Catalytic conversion of CO and hydrogen to methanol was achieved in a self-separating multiphasic system comprising the tailor-made complex [Ru(CO)ClH(MACHO-C )] (MACHO-C =bis{2-[bis(4-dodecylphenyl)phosphino]ethyl}amine) in n-decane as the catalyst phase. Effective catalyst recycling was demonstrated for the carbonate and the amine-assisted pathway from CO to methanol. The polar products MeOH or MeOH/H O generated from the catalytic reactions spontaneously formed a separate phase, allowing product isolation and catalyst separation without the need for any additional solvent.

A "Power-to-X" Route to Acetic Acid via Palladium-Catalyzed Isomerization of Methyl Formate.

The synthesis of acetic acid by formal isomerization of methyl formate (MF) was investigated using molecular catalysts. The base-catalyzed decarbonylation of MF, yielding CO and methanol in situ, was integrated with their palladium-catalyzed recombination for the synthesis of acetic acid and methyl acetate in a one pot reaction. The complex [Pd(Cl) (dppe)] [dppe=1,2-bis(diphenylphosphino)-ethane] in combination with NaI as iodide source and NaOMe as base were identified as promising molecular components to enable the overall conversion.

Aminotriazole Mn(I) Complexes as Effective Catalysts for Transfer Hydrogenation of Ketones.

A catalytic system based on complexes comprising abundant and cheap manganese together with readily available aminotriazole ligands is reported. The new Mn(I) complexes are catalytically competent in transfer hydrogenation of ketones with 2-propanol as hydrogen source. The reaction proceeds under mild conditions at 80 °C for 20 h with 3 % of catalyst loading using either KO Bu or NaOH as base.

Concerning the Role of Supercritical Carbon Dioxide in S 1 Reactions.

A series of S 1-type reactions has been studied under various conditions to clarify the role of supercritical carbon dioxide (scCO ) as reaction medium for this kind of transformations. The application of scCO did not result in higher yields in any of the experiments in comparison to those under neat conditions or in the presence of other inert compressed gases. High-pressure UV/Vis spectroscopic measurements were carried out to quantify the degree of carbocation formation of a highly S 1-active alkyl halide as a function of the applied solvent.

Aqueous Biphasic Systems for the Synthesis of Formates by Catalytic CO Hydrogenation: Integrated Reaction and Catalyst Separation for CO -Scrubbing Solutions.

Aqueous biphasic systems were investigated for the production of formate-amine adducts by metal-catalyzed CO hydrogenation, including typical scrubbing solutions as feedstocks. Different hydrophobic organic solvents and ionic liquids could be employed as the stationary phase for cis-[Ru(dppm) Cl ] (dppm=bis-diphenylphosphinomethane) as prototypical catalyst without any modification or tagging of the complex. The amines were found to partition between the two phases depending on their structure, whereas the formate-amine adducts were nearly quantitatively extracted into the aqueous phase, providing a favorable phase behavior for the envisaged integrated reaction/separation sequence.

Synthesis of α-Amidoketones from Vinyl Esters via a Catalytic/Thermal Cascade Reaction.

A straightforward, modular, and atom-efficient method is reported for the synthesis of α-amidoketones from vinyl esters via a cascade reaction including hydroformylation, condensation with a primary amine, and a rearrangement step giving water as the only byproduct. The reaction sequence can be performed in one pot or as a three-step procedure. The synthetic applicability is demonstrated by the preparation of different α-amidoketones in moderate to good yields.

Unlocking the potential of supported liquid phase catalysts with supercritical fluids: low temperature continuous flow catalysis with integrated product separation.

Solution-phase catalysis using molecular transition metal complexes is an extremely powerful tool for chemical synthesis and a key technology for sustainable manufacturing. However, as the reaction complexity and thermal sensitivity of the catalytic system increase, engineering challenges associated with product separation and catalyst recovery can override the value of the product. This persistent downstream issue often renders industrial exploitation of homogeneous catalysis uneconomical despite impressive batch performance of the catalyst.

Ni-Catalyzed Asymmetric Cycloisomerization of Dienes by Using TADDOL Phosphoramidites.

A library of α,α,α,α-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL)-based phosphoramidites has been synthesized and applied in the Ni-catalyzed cycloisomerization of different dienes. Through the systematic variation of the three structural motifs of the lead structure, that is, the amine moiety, the protecting group, and the aryl substituents, the ligand features could be optimized for the asymmetric cycloisomerization of the model substrate diethyl diallylmalonate. The substrate scope of the new catalytic system was extended to other diallylic substrates, including unsymmetrical dienes.

Highly enantioselective Rh-catalysed hydrogenation of 1-alkyl vinyl esters using phosphine-phosphoramidite ligands.

MatPhos, a good mate for hard tasks: The asymmetric hydrogenation of 1-alkyl vinyl esters, thwarted so far by mediocre ee values and low activities, can now be achieved with MatPhos/Rh catalysts with ee values of 96-99% for a variety of substrates at low catalyst loadings (0.1-1 mol %) and under mild conditions (5-20 bar H2, room temperature). After hydrolysis, the corresponding chiral secondary alkyl alcohols can be obtained in high enantiopurities providing a general and practical route to this important product class.

A fully integrated continuous-flow system for asymmetric catalysis: enantioselective hydrogenation with supported ionic liquid phase catalysts using supercritical CO(2) as the mobile phase.

A continuous-flow process based on a chiral transition-metal complex in a supported ionic liquid phase (SILP) with supercritical carbon dioxide (scCO(2)) as the mobile phase is presented for asymmetric catalytic transformations of low-volatility organic substrates at mild reaction temperatures. Enantioselectivity of >99% ee and quantitative conversion were achieved in the hydrogenation of dimethylitaconate for up to 30 h, reaching turnover numbers beyond 100000 for the chiral QUINAPHOS-rhodium complex. By using an automated high-pressure continuous-flow setup, the product was isolated in analytically pure form without the use of any organic co-solvent and with no detectable catalyst leaching.

Continuous flow organometallic catalysis: new wind in old sails.

Organometallic catalysis is a powerful tool for chemical synthesis, and the field still evolves at a high pace continuously improving efficiencies and opening up new possibilities. However, despite increasing use in specialty and fine chemical production issues of catalyst recovery still hamper broader application and prevent tapping the full potential of this technology on industrial scale. Even though scientists have tackled this problem for decades practicable methods remained scarce.

Continuous-flow homogeneous catalysis using the temperature-controlled solvent properties of supercritical carbon dioxide.

A fully integrated continuous process for homogeneous catalysed reactions in scCO(2) has been developed exploiting the tunable solvent properties of scCO(2). A heated condenser situated above the reaction zone leads to a phase split under isobaric conditions resulting in efficient catalyst retention and recirculation. Continuous isomerisation of allylic alcohols was carried out for over 200 hours time-on-stream demonstrating the viability of this approach.

Quinaphos and Dihydro-Quinaphos phosphine-phosphoramidite ligands for asymmetric hydrogenation.

New derivatives of the Quinaphos ligands and the related Dihydro-Quinaphos ligands based on the more flexible 1,2,3,4-tetrahydroquinoline backbone have been prepared and fully characterised. A general and straightforward separation protocol was devised, which allowed for the gram-scale isolation of the R(a),S(c) and S(a),R(c) diastereomers. These new phosphine-phosphoramidite ligands have been applied in the Rh-catalysed asymmetric hydrogenation of functionalised olefins with the achievement of excellent enantioselectivities (> or = 99%) in most cases and turnover frequency (TOF) values of up to > or = 20,000 h(-1).

Enantioselective catalysis with tropos ligands in chiral ionic liquids.

Enantioselective homogeneous rhodium-catalysed hydrogenation using tropoisomeric biphenylphosphine ligands was accomplished in readily available chiral ionic liquids and the catalytic system could be reused after extraction with scCO(2).

Inverted supercritical carbon dioxide/aqueous biphasic media for rhodium-catalyzed hydrogenation reactions.

An inverted supercritical carbon dioxide (scCO(2))/aqueous biphasic system has been used as reaction media for Rh-catalysed hydrogenation of polar substrates. Chiral and achiral CO(2)-philic catalysts were efficiently immobilised in scCO(2) as the stationary phase, while the polar substrates and products were contained in water as the mobile phase. Notably, product separation and catalyst recycling were conducted without depressurisation of the autoclave.

Catalytic ethylene polymerisation in carbon dioxide as a reaction medium with soluble nickel(II) catalysts.

A series of neutral Ni(II)-salicylaldiminato complexes substituted with perfluorooctyl- and trifluoromethyl groups, [Ni{kappa(2)-N,O-6-C(H)==NAr-2,4-R'(2)C(6)H(2)O}(Me)(pyridine)] (6 a: Ar=2,6-{4-(F(17)C(8))C(6)H(4)}(2)C(6)H(3), R'=I; 6 b: Ar=2,6-{4-(F(3)C)C(6)H(4)}(2)C(6)H(3), R'=I; 6 c: Ar=2,6-{3,5-(F(3)C)(2)C(6)H(3)}(2)C(6)H(3), R'=3,5-(F(3)C)(2)C(6)H(3); 6 d: Ar=2,6-{4-(F(17)C(8))C(6)H(4)}(2)C(6)H(3), R'=3,5-(F(3)C)(2)C(6)H(3); 6 e: Ar=2,6-{3,5-(F(3)C)(2)C(6)H(3)}(2)C(6)H(3), R'=I) were studied as catalyst precursors for ethylene polymerisation in supercritical CO(2). Catalyst precursors 6 a and 6 c, which are soluble in scCO(2), afford the highest polymer yields, corresponding to 2 x 10(3) turnovers. Semicrystalline polyethylene (M(n) typically 10(4) g mol(-1)) is obtained with variable degrees of branching (11 to 24 branches per 1000 carbon atoms, predominantly Me branches) and crystallinities (54 to 21 %), depending on the substitution pattern of the catalyst.

Enantioselective hydrogenation of polar substrates in inverted supercritical CO2/aqueous biphasic media.

An inverted supercritical CO2/aqueous biphasic catalytic system allows highly enantioselective hydrogenation of polar water-soluble substrates and efficient recycling of the CO2-philic catalysts.

Ruthenium-catalysed asymmetric hydrogenation of ketones using QUINAPHOS as the ligand.

Highly enantioselective ruthenium-catalysed hydrogenation of aromatic ketones is achieved with (Ra,S(C))-QUINAPHOS in the presence of achiral and chiral diamines as co-catalysts.

Nickel catalysed asymmetric cycloisomerisation of diethyl diallylmalonate.

Cationic nickel catalysts with monodentate phosphoramidites and Wilke's azaphospholene as ligands are highly regio- and enantioselective catalysts for the cycloisomerisation of diethyl diallylmalonate.

Baeyer-Villiger oxidation in compressed CO2.

The aerobic Baeyer-Villiger oxidation of a wide range of ketones, both cyclic and acyclic to the corresponding esters or lactones can be efficiently carried out in compressed carbon dioxide in the presence of an aldehyde as co-reductant.

Biocatalysis in ionic liquids: batchwise and continuous flow processes using supercritical carbon dioxide as the mobile phase.

A new and environmentally benign protocol for enzymatic reactions in ionic liquids is described using supercritical CO2 as the mobile phase; the products are obtained in solvent-free form and the enzyme/ionic liquid mixture can be recycled in batchwise or continuous flow operations.

Highly enantioselective nickel-catalyzed hydrovinylation with chiral phosphoramidite ligands.

Readily available chiral phosphoramidites are a promising class of ligands for nickel-catalyzed asymmetric hydrovinylation of vinyl arenes. Cooperative effects are operative when ligands with more than one element of chirality are used. Choosing the proper stereochemistry in each part of the modular ligand system leads to high chemoselectivities and excellent enantioselectivities up to 94%.