The development of large scale synthesis of enantiopure and thermally stable (R)- and (S)-BINOL molecules constitutes a key milestone in the field of asymmetric catalysis. Particularly, a great variety of chiral binaphthyl-based phosphorus compounds, herein represented by phosphite and phosphine classes, have earned considerable relevance due to their versatility as ligands in enantioselective metal-catalysed reactions, allowing the preparation of optically active products with the desired enantiopurity. This review highlights the most relevant concepts and accounts regarding general synthetic procedures for binaphthyl-based mono- and bidentate phosphites and phosphines. Furthermore, the search for environmentally benign chemical catalytic processes compelled us to also give special attention to the functionalisation of binaphthyl-based phosphorus ligands for use in alternative reaction media. When available, a critical selection of their applications in catalysis is briefly assessed.
New and highly active mononuclear phosphite gold(I) catalysts are described. Turn-over numbers up to 37,000 for the furan-yne reaction and up to 28,000,000 for the two-fold hydroalkoxylation of alkynes are reported.
The synthesis and full characterization of manganese and chromium metalloporphyrins and hybrid magnetic nanocomposites prepared thereof is described. Their application in homogeneous and heterogeneous sequential epoxidation/CO2 cycloaddition reactions by using O2 or H2O2 as the oxidant showed high activity and selectivity for the preparation of a variety of cyclic carbonates directly from olefins. The combination of manganese and chromium nanocomposites allowed us to set the keystone for the development of a reusable dual catalytic system to transform olefins into cyclic carbonates.
Catalytic carbon dioxide transformation to low valence carbon molecules such as carbon monoxide, formic acid, methanol and methane is a sustainable way to produce fuels and chemicals. Molecular catalysts can be designed to selectively transform CO2 at mild conditions, but a solvent medium is required. Instead, the molecular catalysts can be immobilized on solid supports to facilitate the continuous flow procedure and the separation of the products to recycle the catalytic systems for a more sustainable process. Photosensitive supports may also favor the light‐absorbing steps and electron transfer processes. In this article, the recent results obtained in the photocatalytic CO2‐reduction using catalytic systems formed by molecular compounds anchored on solids are reviewed.
The synthesis and characterization of a hybrid Mn(III)-porphyrin magnetic nanocomposite is described. Moreover, a sustainable methodology for epoxidation of olefins is reported, using O[Formula: see text] as a green oxidant and the magnetic nanoparticle as a recyclable catalyst. High activity in alkene oxidation was observed, with full selectivity for epoxide formation. The magnetic catalyst presented high stability, being recovered and reused in five consecutive runs without loss of catalytic activity or selectivity in cyclooctene oxidation. Moreover, the catalytic system showed very good reactivity toward epoxidation of a range of terminal, substituted, cyclic or acyclic, aliphatic and aromatic olefins, including terpene and steroid derivatives, affording a range of biologically relevant epoxides in excellent yields. The isobutyric acid, formed as side-product, was recovered with high yield and purity, which provides the potential reutilization of this important industrial product.
Metal complexes of meso-arylporphyrins (Cr(III), Fe(III), and Zn(II)) were evaluated in the coupling reaction of cyclohexene oxide (CHO) with CO 2 in compressed medium, where the Cr complexes were demonstrated to be the most active systems, leading predominantly to copolymerisation products. It is noteworthy that no addition of solvent was required. To improve the catalytic activity, and to simultaneously increase the solubility in compressed CO 2 , a new fluorinated catalyst, tetrakis(4-trifluoromethylphenyl)porphyrinatochromium(III) chloride (CrCl-pCF 3 TPP), was applied to this reaction. The alternating copolymerisation of CHO with CO 2 , using the Cr(III) fluorinated porphyrin catalyst, required the use of a co-catalyst, bis(triphenylphosphine)iminium chloride (PPNCl), with the best yields of copolymers being obtained at 80 • C, and CO 2 pressures in the range of 50-110 bar, over a period of 24 h, with a low catalyst/substrate molar ratio (0.07%). The polycarbonate's structure was analysed by 1 H NMR, 13 C NMR, and MALDI-TOF spectroscopy, which demonstrated high carbonate incorporations (98-99%). Gel permeation chromatography revealed number-average molecular weights (M n ) in the range of 4800-12,800 and narrow molecular weight distributions (M w /M n ≤ 1.63).
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