Controlling Regioselectivity in Palladium-Catalyzed C-H Activation/Aryl-Aryl Coupling of 4-Phenylamino[2.2]paracyclophane

Selective activation/functionalization of C-H bonds has emerged as an atom- and step-economical process at the forefront of modern synthetic chemistry. This work reports palladium-catalyzed exclusivelypara-selective C-H activation/aryl-aryl bond formation with a preference overN-arylation under the Buchwald-Hartwig amination reaction of 4-phenylamino[2.2]paracyclophane. This innovative synthetic strategy allows a facile preparation of [2.2]paracyclophane derivatives featuring disparatepara-substitutions at C-4 and C-7 positions in a highly selective manner, gives access to a series of potential candidates for [2.2]paracyclophane-derived new planar chiral ligands. The unprecedented behavior in reactivity and preferential selectivity of C-C coupling over C-N bond formation via C-H activation is unique to the [2.2]paracyclophane scaffold compared to the non-cyclophane analogue under the same reaction conditions. Selective C-H activation/aryl-aryl bond formation and sequential C-N coupling product formation is evidenced unambiguously by X-ray crystallography.Peer reviewe

Anionic N-heterocyclic carbenes derived from sydnone imines such as molsidomine. Trapping reactions with selenium, palladium, and gold

The sydnone imines Molsidomine and 5-(benzoylimino)-3-(2-methoxyphenyl)-1,2,3-oxadiazolium-2-ide gave anionic N-heterocyclic carbenes on deprotonation at C4 which were trapped as methylated selenium adducts, gold complexes (X-ray analysis) as well as palladium complexes (X-ray analysis). The C-13 NMR resonance frequencies of the carbene carbon atom are extremely shifted upfield and appear at delta = 142.1 ppm (Molsidomine carbene) and delta = 159.8 ppm (sydnone imine carbene). The Pd complexes were applied as catalysts in Suzuki-Miyaura and Sonogashira-Hagihara cross-coupling reactions. (C) 2017 Elsevier Ltd. All rights reserved.Peer reviewe

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

The mesomeric betaine imidazolium-1-ylphenolate forms a borane adduct with tris(pentafluorophenyl) borane by coordination with the phenolate oxygen, whereas its NHC tautomer 1-(2-phenol) imidazol-2-ylidene reacts with (triphenylphosphine) gold(I) chloride to give the cationic NHC complex [Au(NHC)(2)][Cl] by coordination with the carbene carbon atom. The anionic N-heterocyclic carbene 1-(2-phenolate) imidazol-2-ylidene gives the complexes [K][Au(NHC-)(2)], [Rh(NHC-)(3)] and [Ni(NHC-)(2)], respectively. Results of four single crystal analyses are presented.Peer reviewe

Acceptor Derivatization of the 4CzIPN TADF System: Color Tuning and Introduction of Functional Groups

We demonstrate modular modifications of the widely employed emitter 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) by replacing one or both nitrile acceptors with oxadiazole groups via a tetrazole intermediate. This allows the introduction of various functional groups including halides, alkynes, alkenes, nitriles, esters, ethers and a protected amino acid while preserving the thermally activated delayed fluorescence (TADF) properties. The substituents control the emission maximum of the corresponding emitters, ranging between 472–527 nm, and show high solid-state photoluminescence quantum yields up to 85%. The TADF emission of two compounds, 4CzCNOXDtBu and 4CzdOXDtBu, a mono- and a bis-oxadiazole substituted 4CzIPN is characterized in detail by time- and temperaturedependent photoluminescence. Solution-processed OLEDs comprising 4CzCNOXDtBu and 4CzdOXDtBu show a significant blue-shift of the emission compared to the reference 4CzIPN, with external quantum efficiencies of 16%, 5.9% and 17% at 100 cdm⁻², respectively

Acceptor Derivatization of the 4CzIPN TADF System : Color Tuning and Introduction of Functional Groups

We demonstrate modular modifications of the widely employed emitter 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) by replacing one or both nitrile acceptors with oxadiazole groups via a tetrazole intermediate. This allows the introduction of various functional groups including halides, alkynes, alkenes, nitriles, esters, ethers and a protected amino acid while preserving the thermally activated delayed fluorescence (TADF) properties. The substituents control the emission maximum of the corresponding emitters, ranging between 472-527 nm, and show high solid-state photoluminescence quantum yields up to 85 %. The TADF emission of two compounds, 4CzCNOXDtBu and 4CzdOXDtBu, a mono- and a bis-oxadiazole substituted 4CzIPN is characterized in detail by time- and temperature-dependent photoluminescence. Solution-processed OLEDs comprising 4CzCNOXDtBu and 4CzdOXDtBu show a significant blue-shift of the emission compared to the reference 4CzIPN, with external quantum efficiencies of 16 %, 5.9 % and 17 % at 100 cd m(-2), respectively.Peer reviewe

Synthesis of New Fused Heterocyclic 2-Quinolones and 3-Alkanonyl-4-Hydroxy-2-Quinolones

Herein, we report the synthesis of 5,12-dihydropyrazino[2,3-c:5,6-c′]difuro[2,3-c:4,5-c′]-diquinoline-6,14(5H,12H)diones, 2-(4-hydroxy-2-oxo-1,2-dihydroquinolin-3-yl)-1,4-diphenyl- butane-1,4-diones and 4-(benzo-[d]oxazol-2-yl)-3-hydroxy-1H-[4,5]oxazolo[3,2-a]pyridine-1-one. The new candidates were synthesized and identified by different spectroscopic techniques, and X-ray crystallography