Search results for "medicinal"
showing 10 items of 2966 documents
ChemInform Abstract: Oppenauer Oxidation of Secondary Alcohols with 1,1,1-Trifluoroacetone as Hydride Acceptor.
2008
1,1,1-Trifluoroacetone (2a) reacts as a hydride-acceptor in the Oppenauer oxidation of secondary alcohols (1) in the presence of diethylethoxyaluminum. The oxidant allows for selective oxidation of secondary alcohols in the presence of primary alcohols.
1-Alkyl- and azeto[1,2-a][1,5]benzodiazepine derivatives in the reaction of o-phenylenediamine with 3-(dimethylamino)propiophenones
2000
The reaction of o-phenylenediamine (4) with one, two or three equivalents of p-substituted 3-dimethylaminopropiophenone hydrochlorides 5a−e was studied. 4-Aryl-2,3-dihydro-1H-1,5-benzodiazepine derivatives 6a−e were obtained in good yields, along with the 1:2-adducts 7c−e and the unexpected 1:3-adducts rac-8c−e. The type of adduct formed is determined by the molar ratio of the reactants 4 and 5 and by the nature of the substituent in the para position of the propiophenone 5.
Electrochemical study of dinuclear ruthenium(II)—arene compounds: Electrogeneration of Ru(II)—Ru(I) species
1987
Abstract The preparation and characterization of Ru(II)—arene compounds [{RuCl2(p-cym)}2(μ-L-L)] where p-cym = p-MeC6H4CHMe2; and L-L = diphenylphosphinomethane (I), 1,1′-bisdiphenylphosphinoferrocene (II), pyrazine (III) and 4,4′-bipyridine (IV), are described. Electrochemical data for these compounds obtained by cyclic voltammetry and coulometry are reported. The electrochemical reduction of compounds I or II yields ruthenium(O) species. However, compounds III or IV containing ligands with delocalized Π orbitals undergo one-electron reduction. The ESR signal detected during the electrolysis of compounds III or IV is consistent with one delocalized electron through the whole dinuclear unit.
New insights into the water-solubilization of thiol-sensitive fluorogenic probes based on long-wavelength 7-hydroxycoumarin scaffolds
2014
Abstract The synthesis and photophysical properties of novel water-soluble phenol-based fluorophores derived from 3-benzothiazolyl-7-hydroxycoumarin and emitting in the range 485–631 nm are described. Further conversion into thiol-sensitive fluorogenic probes through the chemical modification of their hydroxyl group was next investigated. Depending on the type of thiol-reactive quenching moiety used (2,4-dinitrobenzenesulfonyl ester, 2,4-dinitrophenyl ether or benzoquinone-type Michael acceptors) and the water-solubilizing group(s) pre-introduced into the coumarin core, dramatic differences in the thiol-induced fluorescence activation of these pro-fluorophores under physiological conditions…
Manganese(III)-mediated oxidative carbon-carbon bond cleavage of the 1,10-phenanthroline-5,6-dione ligand
1999
[EN] A new manganese(III)-1,10-phenanthroline-5,6-dione (phendione) complex possessing a putative Mn-2(mu-O) (mu-O2CMe)(2) core has been found to undergo a Ligand-based oxidative cleavage of the C(5)-C(6) bond in weak acid aqueous MeOH under aerobic conditions at room temperature to yield 2,2'-bipyridyl-3,3'-dicarboxylate with co-reduction to the corresponding Mn-II-phendione species.
Palladium-catalyzed reaction of boronic acids with chiral and racemic alpha-bromo sulfoxides.
2004
Palladium-catalyzed cross-coupling reactions of racemic alpha-bromo sulfoxides with boronic acids are carried out in either aqueous or nonaqueous medium with formation of a new C sp(3)-C sp(2) bond. The arylation of chiral alpha-bromo sulfoxides occurs without racemization. The cross-coupling reaction is general and gives high yields with arylboronic acids substituted with either donor or acceptor groups but gives poor results with heteroarylboronic acids. The best yields are obtained using degassed solvents and CsF instead of aqueous base. The use of aqueous base and the presence of oxygen favor the homocoupling side reaction.
Substituent effect on oxidative cyclization of aldehyde thiosemicarbazones with ferric chloride
1991
The reactivity of aldehyde thiosemicarbazones 1 with ferric chloride solutions was examined. When compounds 1 are not substituted on the N-2 nitrogen atom formation of 1,3,4-thiadiazole 3 heterocyclic ring was observed. In contrast 1,2,4-triazoline 4 and/or 1,3,4-thiadiazoline 5 heterocyclic rings were afforded when N-2 nitrogen atom carried a methyl or a phenyl group. The reaction mechanism is also discussed.
Enhancing reactivity of carbonyl compounds via hydrogen-bond formation. A DFT study of the hetero-Diels-Alder reaction between butadiene derivative a…
2003
To examine how hydrogen-bond (HB) formation involving chloroform solvent molecules influences the chemical reactivity of ketones, the hetero-Diels-Alder reaction of N,N-dimethyl-1-amino-3-methoxy-1,3-butadiene and acetone has been studied by using density functional theory (DFT) at the B3LYP/6-31G level. The effects of the chloroform on the activation energies have been modeled by means of discrete-continuum models. In the gas phase, the formation of specific HB between acetone and one and two chloroform molecules decreases the activation barriers from 19.3 to 13.6 and 8.5 kcal/mol, respectively. Inclusion of solvent effects by means of combined discrete and polarizable continuum models yie…
Electrocarboxylation of aromatic ketones: Influence of operative parameters on the competition between ketyl and ring carboxylation
2007
Abstract The purpose of this work is to investigate the effect of operational parameters on the competition between the formation of the target 2-hydroxy-2-arylpropanoic acid and ring carboxylation in the electrocarboxylation of aromatic ketones. For the investigated ketones, this competition has been found to be dramatically influenced by different parameters such as the water content and the ratio between the carbon dioxide and the ketone concentrations (q = [CO2]/[ketone]). In particular, the target carboxylic acid formation can be favoured with respect to ring carboxylation by operating at high q ratios or by addition of small amounts of H2O to the reaction medium. An increase of the wa…
Oxidation of N,N-Benzylalkylamines to Nitrones by Mo(VI) and W(VI) Polyperoxo Complexes
1996
Abstract Oxidation of N,N-benzylalkylamines in chloroform by Mo(VI) and W(VI) polyperoxo complexes (PPC) of general formula Q+3{PO4[MO(O2)2]4}3− (Q+ = onium ion) yield the corresponding nitrones as oxidized products quantitatively. Only in the case of N,N-benzylmethylamine the formation of nitrone is accompanied by 25% of benzaldoxime. Oxidation of N,N-benzyltertbutylamine and N,N-benzylisopropylamine follows second order kinetics. This finding does not disqualify the hypothesis that the reaction might occur by a rate determining nucleophilic attack of the amine onto the peroxide oxygens leading, through a Bartlett-type transition state, to the probable formation of the corresponding hydrox…