Search results for "RET"
showing 10 items of 32883 documents
Synthesis of Lamellarin G Trimethyl Ether by von Miller-Plöchl-Type Cyclocondensation
2018
Harnessing Fluorescence versus Phosphorescence Ratio via Ancillary Ligand Fine-Tuned MLCT Contribution
2016
A series of gold(I) alkynyl-diphosphine complexes (XC6H4C2Au)PPh2—spacer—PPh2(AuC2C6H4X); spacer = —C2(C6H4)nC2— (A1, n = 2, X = CF3; A2, n = 2, X = OMe; A3, n = 3, X = CF3; A4, n = 3, X = OMe), —(C6H4)n— (B5, n = 3, X = OMe; B6, n = 4, X = OMe) were prepared, and their photophysical properties were investigated. The luminescence behavior of the titled compounds is dominated by the diphosphine spacer, which serves as an emitting ππ* chromophore. The complexes exhibit dual emission, comprising low and high energy bands of triplet (phosphorescence) and singlet (fluorescence) origins, respectively. The electron-donating characteristics of ancillary groups X significantly affect the LLCT/MLCT c…
Soluble Heterometallic Coordination Polymers Based on a Bis-terpyridine-Functionalized Dioxocyclam Ligand
2010
Soluble homo- and heterometallic coordination polymers containing transition metal cations (Cu(2+), Fe(2+), Co(2+), and Ni(2+) ions) were prepared in a two-step procedure using a polytopic bis(terpyridine)dioxocyclam ligand 1H(2) (dioxocyclam = 1,4,8,11-tetraazacyclotetradecane-5,7-dione). These supramolecular systems incorporate two different metal complexes, the metal cations being located both between two terpyridine units and in the macrocyclic framework. The characterization of these soluble architectures was investigated by cyclic voltammetry, mass spectrometry, viscosimetry, and UV-vis absorption and electron paramagnetic resonance (EPR) spectroscopies. Our results clearly indicate t…
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 …