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Aryl Moieties (aryl + moiety)

Distribution by Scientific Domains

Chemistry	60%

Selected Abstracts

Direct Amination of meso -Tetraarylporphyrin Derivatives , Easy Route to A3B-, A2BC-, and A2B2 -Type Porphyrins Bearing Two Nitrogen-Containing Substituents at the meso -Positioned Phenyl Groups

HELVETICA CHIMICA ACTA, Issue 10 2007
Stanis, aw Ostrowski
Abstract meso -Tetraarylporphyrinato complexes 1a,g (ZnII, CuII, and NiII) bearing one or two nitro-substituted aryl moieties react with 1,1,1-trimethylhydrazinium iodide in the presence of tBuOK in THF at 0,5° or in the presence of KOH in DMSO at 60,70° according to a nucleophilic substitution of an H-atom, thus affording porphyrins 2a,g and 3f,g with amino-functionalized meso -positioned aryl substituents in yields up to 73% (Scheme,1 and Table). The products obtained are attractive intermediates for further derivatization of porphyrins and may be of potential use as sensitizers in photodynamic cancer therapy. [source]

Conformational Stability of A, -(25,35) in the Presence of Thiazolidine Derivatives

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2007
Pietro Campiglia
In the attempt to identify a new lead compound able to modify the conformational preferences of the , -amyloid peptides, a set of new compounds characterized by a thiazolidine ring linked to several different aryl moieties were synthesized. The ability of these compounds to prevent the , -amyloid aggregation was evaluated using circular dichroism and nuclear magnetic resonance techniques. Molecular docking procedure allowed an interpretation of spectroscopic in the key of molecular interaction. [source]

The Effect of Counterion/Ligand Interplay on the Activity and Stereoselectivity of Palladium(II),Diimine Catalysts for CO/p -Methylstyrene Copolymerization

CHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2007
Barbara Binotti Dr.
Abstract The catalytic activity and stereoselectivity of complexes [Pd(,1,,2 -C8H12OMe)(ArNC(R,)C(R,)NAr)]X in the copolymerization of CO and p -methylstyrene have been correlated with their interionic structure in solution and in the solid state, as determined by 19F,1H-HOESY NMR spectroscopy and X-ray diffraction studies, respectively. The highest productivity is obtained with unhindered diimine ligands bearing electron-donating substituents and with the least coordinating counterion. Copolymers with a microstructure ranging from atactic to predominantly isotactic are obtained. The degree of isotacticity increases as the steric hindrance in the apical positions and the coordinating ability of the counterion increase. The counterion is located close to the diimine in both solution and the solid state but it moves toward the palladium as the steric hindrance in the apical positions decreases. When the latter is small the counterion competes with the substrate for apical coordination, and consequently it affects the productivity. In the case of ortho -dimethyl-substituted ligands the counterion is confined in the back, above the NC(R,)C(R,)N moiety, and does not affect the productivity. However, it contributes to increasing the stereoregularity of the copolymer by making the aryl moieties more rigid. With R,=Me and Ar=o -Me2C6H3 an ll of 81,% and 72,% was obtained with X,=CF3SO3, or BArF,, respectively. The isotacticity of the copolymers produced by ortho -monosubstituted catalysts depends greatly on the counterion and ranges from 30,% to 59,% with X,=BArF, and X,=CF3SO3,, respectively, with Ar=o -EtC6H4 and R,=Me. Based on the interionic structural results, this effect can be explained by a greater reduction of the copolymerization rate of Cs -symmetric isomers with respect to their C2 -symmetric counterparts. [source]

Intramolecular Carbolithiation of Allyl o -Lithioaryl Ethers: A New Enantioselective Synthesis of Functionalized 2,3-Dihydrobenzofurans

CHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2005
José Barluenga Prof. Dr.
Abstract A new and easy method for the diastereoselective synthesis of 3-functionalized 2,3-dihydrobenzofuran derivatives from allyl 2-bromoaryl ethers is described. The key step of this transformation involves an intramolecular carbolithiation reaction of allyl 2-lithioaryl ethers. The substituents in both the allyl and the aryl moieties play an important and decisive role in stopping the reaction at the benzofuran thus avoiding a ,-elimination reaction. Finally, this process is amenable to the synthesis of enantiomerically enriched compounds by using (,)-sparteine as a chiral inductor. Se describe un método nuevo y sencillo para la síntesis diastereoselectiva de derivados de 2,3-dihidrobenzofurano funcionalizados en la posición 3 a partir de alil 2-bromoaril éteres. El paso clave de esta transformación implica una reacción de carbolitiación intramolecular de alil 2-litioaril éteres. La presencia de sustituyentes tanto en el resto alílico como en el arílico desempeña un papel decisivo e importante para poder detener la reacción en el estadio de benzofurano, evitando así la reacción de , -eliminación. Finalmente, este proceso puede ser aplicado a la síntesis de compuestos enantioméricamente enriquecidos mediante el uso de (,)-esparteína como inductor quiral. [source]

Vinyl polymerization of norbornene by bis(nitro-substituted-salicylaldiminate)nickel(II)/methylaluminoxane catalysts

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2006
Carlo Carlini
Abstract The polymerization of norbornene has been investigated in the presence of different bis(salicylaldiminate)nickel(II) precursors activated by methylaluminoxane. These systems are highly active in affording nonstereoregular vinyl-type polynorbornenes (PNBs) with high molecular weights. The productivity of the catalytic systems is strongly enhanced (up to 35,000 kg of PNB/mol of Ni × h) when electron-withdrawing nitro groups are introduced on the phenol moiety. On the contrary, the presence of bulky alkyl groups on the N -aryl moiety of the ligand does not substantially affect the activity or characteristics of the resulting PNBs. The catalytic performances are also markedly influenced by the reaction parameters, such as the nature of the solvent, the reaction time, and the monomer/Ni and Al/Ni molar ratios. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1514,1521, 2006 [source]