Search results for "etica"
showing 10 items of 14083 documents
2020
New soluble and intensely near-IR-absorbing transition metal (Ti, Zr, V, Ni) complexes were synthesized using a redox non-innocent N,N’-bis(3,5-di-tertbutyl-2-hydroxy-phenyl) -1,2-phenylenediamine (H4L) as a ligand precursor. In all the complexes, ([Ti(Lox)2, [Zr(Lox)2], [V(Lsq1)(HLox)] and [Ni(HLox)2], two organic molecules coordinate to the metal center as tri- or tetradentate ligands. The solid-state structures of the complexes were determined using single crystal XRD, and the compounds were further characterized with Electrospray Ionisation Mass Spectrometry (ESI-MS). Thermoanalytical measurements indicated the thermal stabilities of the complexes. All compounds absorb strongly in the n…
A tribute to Professor Juan Faus Payá
2018
International audience; Pas de résumé
Unsymmetrically Substituted Bis(phosphino)Ferrocenes Triggering Through-Space 31(P, P′)-Nuclear Spin Couplings and Encapsulating Coinage Metal Cations
2021
International audience; We describe unsymmetrically substituted di-tert-butylated 1,1'-bis(phosphino)ferrocenes, with phosphino substituents R = [5-methyl]-2-furyl = Fu, and R' = phenyl (4a), i-propyl (4b). A modular synthetic approach was applied from the di-tert-butylated ferrocene platform (1), which lead to the formation of new diphosphines by using 1,1'bis(diiodo)-3,3'-bis(tert-butyl)ferrocene (2) as synthetic precursor. In contrast to the cousin non-alkylated unsymmetrically substituted diphosphino-ferrocenes which were reported up to now, these diphosphines showed strong (31 P, P')nonbonded (" ug-p e") nuclear spin-spin coupling. The strength of such internuclear spin-spin coupling c…
Acceptorless dehydrogenative condensation: synthesis of indoles and quinolines from diols and anilines.
2021
The use of diols and anilines as reagents for the preparation of indoles represents a challenge in organic synthesis. By means of acceptorless dehydrogenative condensation, heterocycles, such as indoles, can be obtained. Herein we present an experimental and theoretical study for this purpose employing heterogeneous catalysts Pt/Al2O3 and ZnO in combination with an acid catalyst (p-TSA) and NMP as solvent. Under our optimized conditions, the diol excess has been reduced down to 2 equivalents. This represents a major advance, and allows the use of other diols. 2,3-Butanediol or 1,2-cyclohexanediol has been employed affording 2,3-dimethyl indoles and tetrahydrocarbazoles. In addition, 1,3-pro…
Photocatalytic Giese Addition of 1,4-Dihydroquinoxalin-2-ones to Electron-Poor Alkenes Using Visible Light.
2020
The visible-light photoredox-catalyzed coupling of 1,4-dihydroquinoxalin-2-ones and Michael acceptors was achieved using Ru(bpy)3Cl2 as the photocatalyst and (PhO)2PO2H as an additive. The optimized reaction conditions provide a good yield for the radical conjugate addition products (44 examples) with a wide range of structurally different Michael acceptors. A gram scale reaction using sunlight irradiation is also described. Furthermore, several transformations were carried out with the Giese addition products.
Recent progress in the application of fluorinated chiral sulfinimine reagents
2018
Abstract The development of synthetic methodology allowing for a strategic incorporation of fluorine into target compounds is in a high demand in many areas of the chemical and pharmaceutical industries. In this regard, application of fluorinated chiral sulfinimine reagents, in particularly, N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimine, is one of the most general and practical approaches for preparation of compounds containing pharmacophoric fluoro-amino-keto/hydroxy moieties. This article provides a timely and comprehensive overview of the recent synthetic applications of fluorinated chiral sulfinimine reagents for asymmetric synthesis of fluoro-containing polyfunctional amino-compound…
Synthesis of substituted piperidines by enantioselective desymmetrizing intramolecular aza-Michael reactions.
2018
An organocatalytic enantioselective intramolecular aza-Michael reaction has been described for the first time in a desymmetrization process employing substrates different from cyclohexadienones. By using 9-amino-9-deoxy-epi-hydroquinine as the catalyst and trifluoroacetic acid as a co-catalyst, a series of enantiomerically enriched 2,5-and 2,6-disubstituted piperidines have been obtained in good yields and with moderate diastereoselectivity. Depending on the catalyst/co-catalyst loading ratio, either the major or the minor diastereoisomer of the final piperidine products was achieved with high levels of enantioselectivity. Finally, some mechanistic insights have been considered by means of …
The history and future challenges associated with the hydrogenation of vinyl fluorides
2018
Abstract Catalytic hydrogenation is one of the most powerful transformations available in synthetic chemistry; there have been three Nobel Laureates rewarded for their work in the field. Despite the advances in substrate scope and the development of enantioselective versions of this transformation, vinyl fluorides remain somewhat underrepresented. Successful hydrogenation of vinyl fluorides can give rise to a fluorine-containing stereocenter, an important feature which has great potential in many areas of chemistry. This review aims to explore the history of vinyl fluorides as substrates in hydrogenation reactions, and to highlight modern day challenges and unresolved issues regarding this …
Fluorocyclization of N-Propargylamides to Oxazoles by Electrochemically Generated ArIF2
2019
A sustainable synthesis of 5-fluoromethyl-2-oxazoles by use of electrochemistry has been demonstrated. Hypervalent ArIF2 is generated by direct electrochemical oxidation of iodoarene ArI in Et3N·5HF and mediates the fluorocyclization of N-propargylamides to 5-fluoromethyl-2-oxazoles. The stoichiometry in ArI turned out to be a key parameter in controlling the product selectivity. This electrochemical protocol provides access to fluorinated oxazoles starting from simply available N-propargylamides with yields up to 65% and offers a green alternative over conventional reagent-based approaches.
8-Iodonaphthalene-1-carbaldehyde: A Versatile Building Block for Diversity-Oriented Synthesis.
2016
The scarcely studied 8-halonaphthalene-1-carbaldehyde structure has been converted into the corresponding Ellman’s imine and subjected to several transformations, thus achieving an assorted library of polycyclic carbo- and heterocycles. The potential of this scaffold for Diversity-Oriented Synthesis has been shown. Most of these skeletons are unprecedented and, therefore, cover unexplored regions of the chemical space.