Showing papers in "Canadian Journal of Chemistry in 2001"
TL;DR: An overview of the use of the Heck reaction for the production of fine chemicals is given in this paper, where five commercial products have been identified that are produced on a scale in excess of 1 ton/year.
Abstract: An overview is given of the use of the Heck reaction for the production of fine chemicals. Five commercial products have been identified that are produced on a scale in excess of 1 ton/year. The he...
298 citations
TL;DR: In this article, the reaction of amides with trifluoromethanesulfonic (triflic) anhydride in the presence of pyridine was thoroughly investigated by NMR spectroscopic techniques.
Abstract: The reaction of amides with trifluoromethanesulfonic (triflic) anhydride in the presence of pyridine was thoroughly investigated by NMR spectroscopic techniques. Different pyridinium intermediates ...
133 citations
TL;DR: In this paper, the molecular weight dependence of the lower critical solution temperature of poly(N,N-diethylacrylamide) was studied with 11 samples of the polymer with a number-average molecular weight (Mn) rang.
Abstract: The molecular weight dependence of the lower critical solution temperature of poly(N,N-diethylacrylamide) was studied with 11 samples of the polymer with a number-average molecular weight (Mn) rang...
106 citations
TL;DR: The PCP pincer complex, IrH2{C6H3-2,6-(CH2P-t-Bu2)2} catalyzes the transfer dehydrogenation of primary and secondary alcohols.
Abstract: The PCP pincer complex, IrH2{C6H3-2,6-(CH2P-t-Bu2)2} (1) catalyzes the transfer dehydrogenation of primary and secondary alcohols Dehydrogenation occurs across the CO bond rather than the CC bon
104 citations
TL;DR: Petroporphyrin compositional analysis of a heavy crude oil has been realized by isolation and subsequent ESI-FT-ICR mass spectrometric analysis of the porphrin-containing fractions as discussed by the authors.
Abstract: Petroporphyrin compositional analysis of a heavy crude oil has been realized by isolation and subsequent ESI-FT-ICR mass spectrometric analysis of the porphyrin-containing fractions. Vanadium octae...
99 citations
TL;DR: In this paper, the Abraham general solvation model was used to predict the saturation solubility of crystalline nonelectrolyte solutes in organic solvents and derived equations take the form of log (CS/CW) = c +...
Abstract: The Abraham general solvation model is used to predict the saturation solubility of crystalline nonelectrolyte solutes in organic solvents. The derived equations take the form of log (CS/CW) = c + ...
78 citations
TL;DR: A traceless linker strategy for the solid-supported synthesis of 5-benzoylbenzimidazoles has been developed in this article, where a benzyl cyanide functional group was linked to 2% divinylbenzene cross-linked polystyre.
Abstract: A traceless linker strategy for the solid-supported synthesis of 5-benzoylbenzimidazoles has been developed. A benzyl cyanide functional group was linked to 2% divinylbenzene cross-linked polystyre...
75 citations
TL;DR: Bis-(pentafluorophenyl)boryl ferrocene, 1, was prepared via borylation of Ferrocene with HB(C6F5)2 or via a transmetallation reaction involving FcHgCl and ClB(C 6F5), in 8791% yield as discussed by the authors.
Abstract: Bis-(pentafluorophenyl)boryl ferrocene, 1, was prepared via borylation of ferrocene with HB(C6F5)2 or via a transmetallation reaction involving FcHgCl and ClB(C6F5)2 in 8791% yield. The compound i...
71 citations
TL;DR: The first asymmetric synthesis of 3-aryl substituted 2,3-dihydro-1H-isoindol-1-ones via a tandem nucleophilic 1,2-addition ring closure procedure from SAMP and (or) RAMP hydrazones and subsequent o...
Abstract: The first asymmetric synthesis of 3-aryl substituted 2,3-dihydro-1H-isoindol-1-ones via a tandem nucleophilic 1,2-addition ring closure procedure from SAMP and (or) RAMP hydrazones and subsequent o...
66 citations
TL;DR: An ionic liquid system that undergoes a reversible two phase single phase transformation dependent upon temperature has been used as a novel medium for the transition-metal-catalyzed hydr... as discussed by the authors.
Abstract: An ionic liquid water system that undergoes a reversible two phase single phase transformation dependent upon temperature has been used as a novel medium for the transition-metal-catalyzed hydr...
64 citations
TL;DR: In this paper, both kinetic and mechanistic studies of CO2 hydrogenation were performed in liquid triethylamine and at subcritical CO2 pressures to avoid complications from phase behaviour that are observed under supepe...
Abstract: Kinetic and mechanistic studies of CO2 hydrogenation were performed in liquid triethylamine and at subcritical CO2 pressures to avoid complications from phase behaviour that are observed under supe...
TL;DR: In this paper, a residual lignin isolation method was used to extract about 65% of the oxidized residual Lignins at a purity exceeding 90%. But, the results do not point to a single factor as being responsible for the limits confronting oxygen delignification.
Abstract: Softwood kraft pulp was subjected to a laboratory one- and three-stage oxygen delignification process. Pulp and liquor samples were collected at different stages of the process with particular attention being paid to the early and late stages. A novel residual lignin isolation method extracted about 65% of the oxidized residual lignins at a purity exceeding 90%. Using this methodology coupled to quantitative 31 P NMR, 13 C NMR, 2D heteronuclear (HMQC) NMR spectroscopic and analytical pyrolysis techniques allowed a thorough characterization of the residual and solubilized lignin fractions at the various stages of the process. Our conclusions do not point to a single factor as being responsi - ble for the limits confronting oxygen delignification. Amongst the major factors impeding the effectiveness of oxygen delignification are: (i) the accumulation of relatively inert 5,5 ' biphenyl structures originally present in kraft lignin from dibenzodioxocin ring opening reactions; and (ii) the accumulation of considerably less reactive p-hydroxyphenyl struc- tures. Detailed quantitative information was obtained and discussed in relation to the presence and role of these unreactive phenolic fractions on the residual oxidized lignins. As such we arrived at important conclusions as to why and how these structures remain and accumulate on the fiber. In addition, issues related to the profiles of the total phenolic hydroxyl content of the residual lignins and the remaining arylglycerol β-O-4 structures are discussed.
TL;DR: In this paper, four new 3-hydroxy-chromone derivatives bearing benzofuran and naphthofuran groups were synthesized and they show bathochromic absorption shifts with the focus of designing new fluorescent probes.
Abstract: With the focus of designing new fluorescent probes, four new 3-hydroxy-chromone derivatives bearing benzofuran and naphthofuran groups were synthesized They show bathochromic absorption shifts rel
TL;DR: Fluorescence enhancement of a probe molecule in solution by the container molecule cucurbituril (CB) is reported for the first time and it is proposed that the mode of inclusion involves the phenyl group of the 2,6-ANS, because of the relatively small size of the cucurbitsuril cavity.
Abstract: Fluorescence enhancement of a probe molecule in solution by the container molecule cucurbituril (CB) is reported for the first time. The fluorescence of the probe 2-anilinonaphthalene-6-sulfonate (...
TL;DR: In this paper, the authors describe the development of a new, synthetically useful method of asymmetric synthesis in organic photochemistry, which relies on the use of crystalline organic salts in which the enantioselectivity of a photochemical reaction of an achiral organic ion (for example, a carboxylate anion) is governed in the solid state by the presence of an optically pure counterion.
Abstract: This review describes the development of a new, synthetically useful method of asymmetric synthesis in organic photochemistry. Similar in many ways to the Pasteur procedure for resolving racemic carboxylic acids and organic amines, the method relies on the use of crystalline organic salts in which the enantioselectivity of a photochemical reaction of an achiral organic ion (for example, a carboxylate anion) is governed in the solid state by the presence of an optically pure counterion (for example, an optically active ammonium ion). Such optically pure counterions are termed ionic chiral auxiliaries. Salts containing ionic chiral auxiliaries are required to crystallize in chiral space groups, which provide the asymmetric environment necessary for chiral induction. Using this methodology, we have obtained near-quantitative optical yields in a wide variety of photochemical reactions.Key words: photochemistry, solid state, chiral auxiliaries, asymmetric synthesis, crystal structurereactivity relationships.
TL;DR: In this paper, the infrared spectra of ten salts in aqueous solutions were obtained in their solubility range using attenuated total reflection (ATR) and the salts were: LiCl, NaCl, KCl, CsCl, MgCl2, NaBr, KBr, NaI,...
Abstract: The infrared spectra of ten salts in aqueous solutions were obtained in their solubility range using attenuated total reflection (ATR). The salts are: LiCl, NaCl, KCl, CsCl, MgCl2, NaBr, KBr, NaI, ...
TL;DR: In this article, the (carbonyl)dihydride complex (triphos)Ru(CO)H2] (2) has been synthesized by reaction of the ruthenate [(triphson)RuH3]K (Triphos = MeC(CH2PPh2)3) with ethanol saturated with CO.
Abstract: The (carbonyl)dihydride complex [(triphos)Ru(CO)H2] (2) has been synthesized by reaction of the ruthenate [(triphos)RuH3]K (triphos = MeC(CH2PPh2)3) with ethanol saturated with CO. A single crystal...
TL;DR: BINOL-aluminum complexes were successfully employed as mediators and catalysts in asymmetric Baeyer-Villiger rearrangements of cyclobutanones.
Abstract: BINOL-aluminum complexes were successfully employed as mediators and catalysts in asymmetric Baeyer-Villiger rearrangements of cyclobutanones. Good enantioselectivies were achieved with only 15 mol...
TL;DR: In this paper, the homogeneous catalytic hydrosilation-hydrogenation of pyridines was observed in the presence of Cp2TiMe2 (Cp = η5-C5H5) and CpCp*TiMe 2 (cp* = ǫ-5C5Me5) as catalysts and using PhSiH3 or PhMeSiH2 a...
Abstract: The homogeneous catalytic hydrosilation-hydrogenation of pyridines is observed in the presence of Cp2TiMe2 (Cp = η5-C5H5) and CpCp*TiMe2 (Cp* = η5-C5Me5) as catalysts and using PhSiH3 or PhMeSiH2 a...
TL;DR: In this article, a dimethoxy-bridged dimer of stoichiometry (La3+)2(OCH3)2 was used for methanolysis of both aryl and alkyl esters.
Abstract: La3+ catalysis of the methanolysis of the esters p-nitrophenyl, 2,4-dinitrophenyl, and phenyl acetate (13), phenyl benzoate (4), and ethyl, i-propyl, cyclohexyl, and tert-butyl acetate (5, 6a, 6b, 7) was studied at 25°C as a function of sspH and [La(OTf)3]. The active form of the catalyst is attributed to a dimethoxy-bridged dimer of stoichiometry (La3+)2(OCH3)2, having maximum activity at sspH 8 to 9. For preparative reactions, the active catalyst can be made in situ simply by adding 0.01 equiv of La(OTf)3, and 0.01 equiv of NaOCH3 to a methanol solution containing the ester (1 M). Strong catalysis of methanolysis of both aryl and alkyl esters was observed, although tert-butyl acetate was inert. At sspH 8.5, where the catalyst is maximally active, the transesterification reactions are accelerated by 40 000-fold to 18 000 000-fold in the presence of as little as 5 mM catalyst relative to the background reaction depending on the ester structure. A mechanism for catalysis of transesterification is present...
TL;DR: The well-known trans-cis-trans photoisomerization of azobenzenes produces at least three different kinds of motion in the polymer materials to which the azobenes are bound.
Abstract: The well-known transcistrans photoisomerization of azobenzenes produces at least three different kinds of motion in the polymer materials to which the azobenzenes are bound. The first is a photoi...
TL;DR: In this article, it was found that 3-iodo-2-formyl-1-tosylpyrroles efficiently coupled with a variety of arylboronic acids in the presence of PdCl2(dppf) as catalyst.
Abstract: Suzuki cross-coupling reactions of 3-pyrroleboronic acid derivatives with haloaromatics and the reverse process i.e., the coupling of 3-iodo(bromo)pyrroles with arylboronic acids have been investigated as a potential key step in the synthesis of (-)-rhazinilam and analogues. It was found that 3-iodo-2-formyl-1-tosylpyrroles efficiently coupled with a variety of arylboronic acids in the presence of PdCl2(dppf) as catalyst. This catalytic system is compatible with a broad spectrum of arylboronic acids - electron-rich, electron-poor, hindered, heterocyclic - which easily coupled with the pyrrole substrate.
TL;DR: New complexes of the type RuCl2(p-cymene)L where the ligand L is either a phosphine or a stable triazolinylidene carbene have been tested and compared to the Grubbs' benzylidene complex RuCl 2(=CHPh... as discussed by the authors.
Abstract: New complexes of the type RuCl2(p-cymene)L where the ligand L is either a phosphine or a stable triazolinylidene carbene have been tested and compared to the Grubbs' benzylidene complex RuCl2(=CHPh...
TL;DR: Ring-opening of N-(PhF)serine-derived cyclic sulfamidate 17 was achieved with different nucleophiles to prepare a variety of amino acid analogs and β-keto ketones were converted to prolines and pyrazole amino acids.
Abstract: Ring-opening of N-(PhF)serine-derived cyclic sulfamidate 17 was achieved with different nucleophiles (β-keto esters, β-keto ketones, dimethyl malonate, nitroethane, sodium azide, imidazole, and pot...
TL;DR: In this paper, the kinetics of ruthenium(III) catalyzed oxidation of L-valine by permanganate in alkaline medium at a constant ionic strength was studied spectrophotometrically.
Abstract: The kinetics of ruthenium(III) catalyzed oxidation of L-valine by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction between permanganate and L-valine in alkaline medium exhibits 2:1 stoichiometry (KMnO4:L-valine). The reaction shows first-order dependence on the concentration of permanganate and ruthenium(III) and less than unit-order dependence on the concentrations of L-valine and alkali. The reaction rate increases both with an increase in ionic strength and a decrease in solvent polarity of the medium. Initial addition of reaction products did not significantly affect the rate. A mechanism involving the formation of a complex between catalyst and substrate has been proposed. The activation parameters were computed with respect to the slowest step of the mechanism.Key words: oxidation, L-valine, catalysis, ruthenium(III), kinetics.
TL;DR: The in situ rhodium-catalyzed addition of catecholborane (HBcat, cat = 1,2-O2C6H4) and pinacolboranes (HBpin, pin = 1 2 O2C2Me4) to allylamine, allylimine, 2- and 4-vinylpyridines, and a thienyl imi...
Abstract: The in situ rhodium-catalyzed addition of catecholborane (HBcat, cat = 1,2-O2C6H4) and pinacolborane (HBpin, pin = 1,2-O2C2Me4) to allylamine, allylimine, 2- and 4-vinylpyridines, and a thienyl imi...
TL;DR: Starting from the functionalized Josiphos derivatives (R)-1]-(S)-2-(diphenylphosphino)-1'-(dimethyl-3''-aminopropylsilyl)-ferrocenyl]]-ethyldicyclohexylphphosphine ((R)-(S)3), (R]-1-[(S]-2]-diphensylphophosphino]-1'-hydroxy propyl]ethylldicyl)FERCORENyl] as discussed by the authors, a series of dendrimers
Abstract: Starting from the functionalized Josiphos derivatives (R)-1-[(S)-2-(diphenylphosphino)-1'-(dimethyl-3''-aminopropylsilyl)-ferrocenyl]ethyldicyclohexylphosphine ((R)-(S)-3), (R)-1-[(S)-2-(diphenylphosphino)-1'-(hydroxy methyl) ferrocenyl]ethyldicyclohexylphosphine ((R)-(S)-4), and (R)-1-[(S)-2-(diphenylphosphino)-1'-(3''-hydroxy propyl)ferrocenyl]ethyldicyclohexylphosphine ((R)-(S)-5), a series of dendrimers containing up to sixteen ferrocenyl diphosphine units were prepared. Dendrimer cores are based on benzene 1,3,5-tricarboxylic acid and 1,3,5,7-adaman tanetetracarboxylic acid, with 5-substituted isophthalic acid derivatives constituting the branching units. The dendrimers have been used in three different asymmetric catalytic reactions: Rh-catalyzed hydrogenation of dimethyl itaconate, Pd-catalyzed allylic substitution, and Rh-catalyzed hydroboration of styrene with catecholborane. In all three reactions the selectivity obtained with the dendrimers was very similar to the one obtained with the parent l...
TL;DR: The reaction of N-salicylidene-2-aminophenolate (SAP-H2) derivatives with phenyl boronic acid afforded five new boron bicyclic species in moderate yields as mentioned in this paper.
Abstract: The reaction of N-salicylidene-2-aminophenolate (SAP-H2) derivatives with phenyl boronic acid afforded five new boron bicyclic species in moderate yields, as confirmed by an X-ray study of the boro...
TL;DR: The formal total synthesis of the marine metabolite (+)-calyculin A was reported in this article, which involved the use of Brown allylboration chemistry to control the relative and absolute stereochemis...
Abstract: The formal total synthesis of the marine metabolite (+)-calyculin A is reported. The key steps involve (i) the use of Brown allylboration chemistry to control the relative and absolute stereochemis...
TL;DR: In this paper, the reaction of RuCl2(PPh3)3 with bis(dicyclohexyl)-1,4-phosphinobutane (dcypb) under N2 affords access to a formerly elusive family of dcypb complexes based on the RuCl 2(PP) core.
Abstract: Reaction of RuCl2(PPh3)3 with bis(dicyclohexyl)-1,4-phosphinobutane (dcypb) under N2 affords access to a formerly elusive family of dcypb complexes based on the RuCl2(PP) core. Under Ar or vacuum a...