A Telescoped Strategy for the Preparation of Five-Membered Hetero- and Carbocycles via Hydrogen Atom Transfer Photocatalysis in Flow.

Five-membered heterocycles such as pyrroles and thiophenes, along with cyclopentenones, are key scaffolds in pharmaceutical chemistry. However, the synthesis of these motifs via diversity oriented synthesis is hindered by the limited accessibility of unsymmetrical 1,4-diketones. Herein, a practical and sustainable flow protocol is presented for the telescoped synthesis of pyrroles, thiophenes, and cyclopentenones.

Recyclable, Biobased Polycarbonates and Polyesters by Naphthoxy-Imine Zinc and Magnesium Complexes.

Naphthoxy-imine pyridine zinc and magnesium complexes were synthesized and fully characterized by nuclear magnetic resonance (NMR). In the presence of an alcohol as initiator, both complexes promoted the ring-opening polymerization (ROP) of L-lactide (L-LA), ε-caprolactone (ε-CL), β-butyrolactone (β-BL), trimethylene carbonate (TMC), and 1-methyl trimethylene carbonate (Me-TMC), which was purposely synthesized from CO and the appropriate diol. The zinc complex exhibited notably high activity, particularly in the polymerization of lactide and TMC, and was subsequently employed in the synthesis of polytrimethylene carbonate-based diblock and random copolymers with both ε-CL and L-LA.

Mechanochemical Activation of NaHCO: A Solid CO Surrogate in Carboxylation Reactions.

Carbon dioxide, a primary driver of global warming, offers a promising feedstock for valuable chemical synthesis. Nonetheless, the reliance on highly pressurized canisters and specialized equipment limits its practical application in fine chemical synthesis. This study explores the innovative use of sodium bicarbonate (NaHCO) as a safe, solid, on-demand source of CO under mechanochemical conditions to perform carboxylation reactions.

Mechanochemical Aerobic Activation of Metallic Copper for the Synthesis of 1,4-Allenynes.

Mechanical activation of zero-valent metals is emerging as a new paradigm in sustainable synthesis, opening up a broad swath of chemical space under more practical conditions than solution-phase methods. Contrary to its neighboring elements in the periodic table, copper has been significantly overlooked in this domain, especially for CC bond formation. Herein, a mechanochemical method for synthesizing >25 previously unreported conjugated allenynes-a valuable scaffold in organic synthesis is presented-through copper-catalyzed homocoupling of propargylic esters.

Photomechanochemistry: harnessing mechanical forces to enhance photochemical reactions.

Photomechanochemistry, i.e., the merger of light energy and mechanical forces, is emerging as a new trend in organic synthesis, enabling unique reactivities of fleeting excited states under solvent-minimized conditions.

Waste cooking oils as a sustainable feedstock for bio-based application: A systematic review.

Waste cooking oils (WCOs) are common wastes and promising green, eco-friendly and sustainable feedstocks for bio-based applications. While the primary valorisation strategy revolves around the concept of waste-to energy, new research trends have emerged in the last decade. This systematic review provides a comprehensive analysis of the current state of the art in the conversion of WCOs into bio-based molecules.

Ion-Pairing Stereodynamic Probes for Circular Dichroism Chiral Sensing of Amines.

Tris(2-pyridylmethyl)amine () and tris(2-phenolmethyl)amine () metal complexes have been extensively used for catalysis and molecular recognition applications. In particular, due to their ability to form stereodynamic complexes through the helical arrangement of the ligand around the metal in a propeller shape, chiroptical sensing has been extensively investigated. In particular, the capability of the analyte, usually a Lewis base, to bind the metal complex has been the predominant recognition motif.

Keratinous and corneous-based products towards circular bioeconomy: A research review.

Keratins and corneous proteins are key components of biomaterials used in a wide range of applications and are potential substitutes for petrochemical-based products. Horns, hooves, feathers, claws, and similar animal tissues are abundant sources of α-keratin and corneous β-proteins, which are by-products of the food industry. Their close association with the meat industry raises environmental and ethical concerns regarding their disposal.

Novel ligands from direct benzylic functionalisation of tris(2-pyridylmethyl)amine.

Tris-(2-pyridylmethyl)amines (TPA or TPMA) are polipyrydine-based ligands extensively used in catalysis and supramolecular chemistry due their capability to form stable tetradentate complexes with a large variety of metals. The unsubstituted ligand, which is also commercially available, can be synthesised by consecutive alkylation of a picoline or by reductive amination of a pyridine aldehyde. In this article, we report a novel synthetic method which opens to the post-functionalisation of these ligands in the benzylic position.

CO-Based Polycarbonates through Ring-Opening Polymerization of Cyclic Carbonates Promoted by a NHC-Based Zinc Complex.

A backbone-substituted N-heterocyclic carbene (NHC) zinc complex, in combination with alcohol initiators, has been shown to be an effective catalyst for the ring-opening polymerization (ROP) of trimethylene carbonate (TMC) to poly(trimethylene carbonate) (PTMC) devoid of oxetane linkages. The ROP of TMC proceeded in solution to give PTMC, possessing controlled molecular mass (2500 < < 10000) and low dispersity ( ∼ 1.2).

Rhenium Alkyne Catalysis: Sterics Control the Reactivity.

Metathesis reactions, including alkane, alkene, and alkyne metatheses, have their origins in the fundamental understanding of chemical reactions and the development of specialized catalysts. These reactions stand as transformative pillars in organic chemistry, providing efficient rearrangement of carbon-carbon bonds and enabling synthetic access to diverse and complex compounds. Their impact spans industries such as petrochemicals, pharmaceuticals, and materials science.

Industrial Production of Proteins with -.

Since the mid-1960s, methylotrophic yeast (previously described as ) has received increasing scientific attention. The interest for the industrial production of proteins for different applications (e.g.

[OSSO]-Type Chromium(III) Complexes for the Reaction of CO with Epoxides.

In this work, four new mononuclear Cr(III) complexes (2-5) bearing bis-thioether-diphenolate, [OSSO]-type ligands, were synthesized and characterized. These complexes in combination with bis(triphenylphosphine)iminium chloride (PPNCl) promoted the coupling of CO with epoxides. Depending on the type of substrate and the conditions, the reaction results in the selective formation of either polycarbonate or cyclic carbonate.

Pd-Catalysed oxidative carbonylation of α-amino amides to hydantoins under mild conditions.

The first example of palladium-catalysed oxidative carbonylation of unprotected α-amino amides to hydantoins is described here. The selective synthesis of the target compounds was achieved under mild conditions (1 atm of CO), without ligands and bases. The catalytic system overrode the common reaction pathway that usually leads instead to the formation of symmetrical ureas.

Change of Selectivity in C-H Functionalization Promoted by Nonheme Iron(IV)-oxo Complexes by the Effect of the -hydroxyphthalimide HAT Mediator.

A kinetic analysis of the hydrogen atom transfer (HAT) reactions from a series of organic compounds to the iron(IV)-oxo complex [(N4Py)Fe(O)] and to the phthalimide -oxyl radical (PINO) has been carried out. The results indicate that a higher activating effect of α-heteroatoms toward the HAT from C-H bonds is observed with the more electrophilic PINO radical. When the -hydroxy precursor of PINO, hydroxyphthalimide (NHPI), is used as a HAT mediator in the oxidation promoted by [(N4Py)Fe(O)], significant differences in terms of selectivity have been found.

NSSN-Type Group 4 Metal Complexes in the Ring-Opening Polymerization of l-Lactide.

A new class of zirconium and hafnium complexes coordinated by linear dianonic tetradentate NSSN ligands is reported. The ligands feature two amide functions coupled with two thioether groups linked by a central flexible ethane bridge and two lateral rigid phenylene bridges and differ for the substituents on the aniline nitrogen atoms, i.e.

Phenylene-Bridged OSSO-Type Titanium Complexes in the Polymerization of Ethylene and Propylene.

The dichloro titanium complexes (OSSO )TiCl () and (OSSO)TiCl () bearing -phenylene-bridged OSSO-type ligands [OSSO -H = 6,6'-((1,2-phenylenebis(sulfanediyl))bis(methylene))bis(2,4-di--butyphenol) and OSSO-H = 6,6'-((1,2-phenylenebis(sulfanediyl))bis(methylene))bis(2,4-bis(2-phenylpropan-2-yl)phenol)] were prepared and characterized. The X-ray structure of revealed that Ti atom has an octahedral coordination geometry with an - wrapping of the [OSSO] ligand. In solution at 25 °C, mainly retains the symmetric structure, whereas shows an equilibrium between - and -symmetric stereoisomers.

Aerobic Oxidation and Oxidative Esterification of 5-Hydroxymethylfurfural by Gold Nanoparticles Supported on Nanoporous Polymer Host Matrix.

The aerobic oxidation and oxidative esterification of 5-hydroxymethylfurfural (HMF) catalyzed by gold nanoparticles (AuNPs) supported on a semicrystalline nanoporous multiblock copolymer matrix consisting of syndiotactic poly(styrene)-cis-1,4-poly(butadiene) (sPSB) have been investigated. Depending on the reaction parameters (support nanoporosity, presence of water, solvent, temperature, cocatalyst, oxygen pressure), the conversion of HMF can be finely addressed to the formation of the desired oxidation product, such as 2,5-diformylfuran (DFF), 5-formylfuran-2-carboxylic acid (FFCA), methyl 5-(hydroxymethyl)furan-2-carboxylate (MHMFC), dimethyl furan-2,5-dicarboxylate (DMFC), and furan-2,5-dicarboxylic acid (FDCA), under optimized reaction conditions. The AuNP-sPSB catalyst is highly effective and selective because the polymer support acts as a conveyor and concentrator of the reactants toward the catalytic sites.

Glycidol: an Hydroxyl-Containing Epoxide Playing the Double Role of Substrate and Catalyst for CO Cycloaddition Reactions.

Glycidol is converted into glycerol carbonate (GC) by coupling with CO in the presence of tetrabutylammonium bromide (TBAB) under mild reaction conditions (T=60 °C, PCO2 =1 MPa) in excellent yields (99 %) and short reaction time (t=3 h). The unusual reactivity of this substrate compared to other epoxides, such as propylene oxide, under the same reaction conditions is clearly related to the presence of a hydroxyl functionality on the oxirane ring. Density functional theory calculations (DFT) supported by H NMR experiments reveal that the unique behavior of this substrate is a result of the formation of intermolecular hydrogen bonds into a dimeric structure, activating this molecule to nucleophilic attack, and allowing the formation of GC.

Synthesis and Characterization of Fe (2,2'-bipyridine) (2-aminoethyl-pyridine) and its Reaction with Dihydrogen.

Fe (bpy)(pyea) (2; bpy=2,2'-bipyridine, pyea=2-aminoethyl-pyridine), a 16-electron species, was synthesized by reduction of FeCl (bpy)(pyea) (1) using Na-strips. It is a diamagnetic low-melting solid (m.p.

Thioether-triphenolate bimetallic iron(III) complexes as robust and highly efficient catalysts for cycloaddition of carbon dioxide to epoxides.

The selective and effective synthesis of organic carbonates under mild conditions, starting from carbon dioxide and oxiranes, catalyzed by metal complexes is currently a focus of interest for both industrial and academic researchers. We recently developed a novel thioether-triphenolate iron(III) catalyst (Ct-BU) that has proven to be highly active for the coupling of CO2 with epoxides, resulting in cyclic organic carbonates under solvent-free conditions. In the current work, the properties of this novel class of catalysts were extensively investigated.

Improved 1,3-Propanediol Synthesis from Glycerol by the Robust Lactobacillus reuteri Strain DSM 20016.

Various Lactobacillus reuteri strains were screened for the ability to convert glycerol to 1,3- propanediol (1,3-PDO) in a glycerol-glucose co-fermentation. Only L. reuteri DSM 20016, a well-known probiotic, was able to efficiently carry out this bioconversion.