Search results for "SUBSTITUTION"

Aryl azides formation under mild conditions: a kinetic study in some ionic liquid solutions.

2009

The kinetics of nucleophilic aromatic substitution of three nitrothiophene derivatives in different [1-butyl-3-methylimidazolium][N(3)]/ionic liquid binary mixtures was studied spectrophotometrically at 298 K. Ionic liquids differing for cation structure (imidazolium or pyrrolidinium) and for size, shape, and coordination ability of the anion ([BF(4)(-)], [PF(6)(-)], [SbF(6)(-)], and [NTf(2)(-)]) were used. Furthermore, in order to have a comparison with conventional organic solvents, the target reaction was also carried out in DMF solution at increasing concentration of NaN(3) or [bmim][N(3)]. Data collected show that the reaction occurs faster in DMF than in ionic liquid solution. Further…

Ionic liquids/[bmim][N3] mixtures: promising media for the synthesis of aryl azides by SNAr

2008

The nucleophilic aromatic substitution of some activated aryl or heteroaryl halides has been performed in ionic liquid solution, using the 1-butyl-3-methylimidazolium azide as a nucleophile. The reaction course was studied varying the structures of both substrates and ionic liquids. In particular, in the latter case, the reaction of 2-bromo-5-nitrothiophene was carried out in five different ionic liquids ([bmim][BF 4], [bmim][PF 6], [bmim][NTf 2], [bm 2im][NTf 2], and [bmpyrr][NTf 2]). Finally, for all the substrates considered, a comparison with data obtained in MeOH solution in the presence of NaN 3 was also performed. Data collected indicate that in some cases it is possible to obtain ar…

2015

Visuo-auditory sensory substitution systems are augmented reality devices that translate a video stream into an audio stream in order to help the blind in daily tasks requiring visuo-spatial information. In this work, we present both a new mobile device and a transcoding method specifically designed to sonify moving objects. Frame differencing is used to extract spatial features from the video stream and two-dimensional spatial information is converted into audio cues using pitch, interaural time difference and interaural level difference. Using numerical methods, we attempt to reconstruct visuo-spatial information based on audio signals generated from various video stimuli. We show that de…

Synthesis of aryl azides: A probe reaction to study the synergetic action of ultrasounds and ionic liquids

2011

Abstract The combined effect of ultrasounds and ionic liquids was used to perform the synthesis of aryl azides by nucleophilic aromatic substitution in ionic liquid/[1-butyl-3-methylimidazolium][N 3 ] binary mixtures. The ultrasounds efficiency was analyzed as a function of the substrate and of the ionic liquid structure. In the first case, both 6π and 10π electrons aryl halides were considered. As far as the ionic liquid structure is concerned, both aromatic and aliphatic ionic liquids were taken into account. Among aromatic cations, the effects due to different ability in giving hydrogen bond or π–π interactions were considered. The use of a geminal ionic liquid having an aromatic spacer …

Triazolopyridines. Part 8.1 Nucleophilic substitution reactions of 5-bromo[1,2,3]triazolo[5,1-a]isoquinoline and 7-bromo[1,2,3]-triazolo[1,5-a]pyridi…

1988

Abstract Nucleophilic substitution of 5-bromotriazoloisoquinoline (3) and of 7-bromo-3-methyltriazolopyridine (6) proceeds readily to give a range of 5-substituted triazoloisoquinolines (4a)-(4e), and of 7-substituted triazolopyridines (7a)-(7h) respectively. Triazoloisoquinolines have been converted into 1,3-disubstituted isoquinolines (11)-(13), (15), and (16), and triazolopyridines into 2,6-disubstituted pyridines (17)-(19). Of secondary amine nucleophiles, only piperidine reacted with 7-bromo-3-methyltriazolopyridine (6) to give the 7-substituted derivative (7g). A second product in this reaction was a 2,6-disubstituted pyridine (8); the similar compounds (20)-(24) were the only product…

Nucleophilic substitutions on bromotriazolopyridines - an improved route to 2,6-disubstituted pyridines and to 1,3-disubstituted isoquinolines

1986

Abstract A regiospecific synthesis of 2,6-disubstituted pyridines and of 1,3-disubstituted isoquinolines is described.

Palladium-Catalyzed Arylation of Linear and Cyclic Polyamines.

2005

Synthetic protocols for the palladium-catalyzed arylation of various linear and cyclic polyamines and polyoxapolyamines has been worked out. Pd(0) and Pd(II) complexes with such phosphine ligands as dppf, BINAP, PPF-OMe, P(tBu) 3 , 2-ditert-butylphosphino- 1,1'-biphenyl have been explored in the catalytic amination reactions. Monoamination of chloro-, bromo-, and iodoarenes with di-, tri-, and tetraamines have been carried out, condi- tions for di- and polyarylation of linear polyamines have been elaborated. Successful aryla- tion of 1,4,7,10-tetraazacyclododecane (cyclene) and 1,4,8,11-tetraazacyclotetradecane (cy- clam) have been conducted. Intramolecular diamination of dihaloarenes such …

ChemInform Abstract: Synthesis of Bis(indolylmaleimide) Macrocycles

2000

The synthesis of a novel class of macrocyclic bis(indolylmaleimides) is reported. The key step involves the intermolecular connection of 2,2′-bridged indoles with 3,4-dibromo-2,5-dihydro-1H-2,5-pyrroledione (dibromomaleimide) derivatives. The bis(indolylmaleimides) afforded by this method were further processed by intramolecular nucleophilic substitution of the remaining bromo substituents forming flexible N-substituted macrocycles (9a-9j, 10a-10e) and, by connecting both maleimides, semi rigid macrocycles (7a-7xx).

Synthesis of bis(indolylmaleimide) macrocycles

2000

The synthesis of a novel class of macrocyclic bis(indolylmaleimides) is reported. The key step involves the intermolecular connection of 2,2′-bridged indoles with 3,4-dibromo-2,5-dihydro-1H-2,5-pyrroledione (dibromomaleimide) derivatives. The bis(indolylmaleimides) afforded by this method were further processed by intramolecular nucleophilic substitution of the remaining bromo substituents forming flexible N-substituted macrocycles (9a-9j, 10a-10e) and, by connecting both maleimides, semi rigid macrocycles (7a-7xx).

Relevant associations of the glucokinase regulatory protein/glucokinase gene variation with TAG concentrations in a high-cardiovascular risk populati…

2012

The SNP rs1260326 (P446L) and rs1799884 ( − 30G>A) for the glucokinase regulatory protein (GCKR) and glucokinase (GCK) genes, respectively, have been associated with opposing effects on TAG and glucose concentrations. However, their genetic modulation by diet (dietary patterns or foods) remains to be investigated. We studied 945 high-cardiovascular risk subjects aged 67 (sd 6) years who participated in the PREvención con DIeta MEDiterránea-Valencia Study. Demographic, clinical, biochemical and genetic data were obtained. Adherence to the Mediterranean diet (MD) and food intake were measured by validated questionnaires. Carriers of the L allele of GKCR had significantly higher TAG concent…