Showing papers on "Methyl vinyl ketone published in 2003"
TL;DR: In this article, living polymerization of ethylene with palladium(II) diimine complexes coupled with use of a functionalized initiator and/or cleavage of the palladium−polymer bond with various reagents provides a protocol for synthesis of mono-and di-end functionalized, branched, amorphous polyethylenes.
Abstract: Living polymerizations of ethylene with palladium(II) diimine complexes coupled with use of a functionalized initiator and/or cleavage of the palladium−polymer bond with various reagents provides a protocol for synthesis of mono- and di-end-functionalized, branched, amorphous polyethylenes. The functional initiator used is the chelate complex (Ar = 2,6-(iPr)2C6H3) (3). The alkyl chain is cleaved by insertion of alkyl acrylates or methyl vinyl ketone, followed by cleavage with Et3SiH to generate alkyl ester or methyl ketone end groups, respectively. Insertion of 5-hexen-1-ol, followed by chain running and β-elimination, results in formation of aldehyde end groups. Conditions for living polymerization of propylene, 1-hexene, and 1-octadecene have also been established. Rates of first monomer insertion and subsequent chain growth are shown to be a sensitive function of the palladium complex used for initiation and the nature and concentration of auxiliary nitrile ligands. Block copolymers of ethylene and 1-o...
215 citations
TL;DR: In this paper, the aza-Baylis-Hillman reaction of N-sulfonated imines with methyl vinyl ketone (MVK) promoted by chiral phosphine Lewis base: (R)-2′-diphenylphosphanyl-[1, 1′]binaphthalenyl-2-ol (10 mol), the adducts were obtained in good yields with high ee (70-94% ee) at −30 °C in THF.
147 citations
TL;DR: It has been found that the chiral amines catalyze the formation of optically active substituted 5-keto aldehydes in good yields and enantioselectivities, using aldeHydes and, e.g., methyl vinyl ketone as starting compounds.
Abstract: Chiral amines such as (S)-2-[bis(3,5-dimethylphenyl)methyl]pyrrolidine and the C2-symmetric (2S,5S)-2,5-diphenylpyrrolidine can catalyze the direct enantioselective Michael addition of simple aldehydes to vinyl ketones. The conditions for this organocatalytic reaction have been optimized and it has been found that the chiral amines catalyze the formation of optically active substituted 5-keto aldehydes in good yields and enantioselectivities, using aldehydes and, e.g., methyl vinyl ketone as starting compounds. Taking into account that the chiral amine can activate the aldehyde and/or the enone, the mechanism for the reaction has been investigated. On the basis of intermediate synthesis, nonlinear effect, and theoretical investigations, the mechanism for the catalytic direct enantioselective Michael addition of aldehydes to vinyl ketones is discussed.
145 citations
TL;DR: In this paper, the reaction of α,β-unsaturated ketones with electron-rich arenes catalyzed by gold(III) chloride both, a Friedel-Crafts-type mechanism and an initial metallation, are evaluated.
Abstract: For the reaction of α,β-unsaturated ketones with electron-rich arenes catalyzed by gold(III) chloride both, a Friedel–Crafts-type mechanism and an initial metallation, are evaluated. Gold(III) chloride has proven to be an efficient catalyst under very moderate reaction conditions, however, in the case of sterically demanding products HBF4 turned out to be the superior catalyst.
139 citations
TL;DR: In this article, the effect of the para substituents on the partial charge at the palladium(II) center was investigated by means of the Mulliken population analysis, and it was found that various para functionalities can be used for immobilization of the pincer−metal complexes without affecting the catalytic activity of individual sites.
Abstract: Several para-substituted NCN-pincer palladium(II) complexes (1a−g and 6a−g) {NCN = [C6H3(CH2NMe2)2-2,6]−, para = 4-position} have been prepared and the electronic influences of the para substituents were studied in catalysis as well as by DFT calculations (B3LYP/LANL2DZ). From DFT calculations, it was found that the para substituent exerts only a minor effect on the partial charge, investigated by means of the Mulliken population analysis, at the palladium(II) center. Also, when the para-functionalized, cationic NCN−PdII complexes 6a−g were applied as Lewis acid catalysts in the double Michael reaction between methyl vinyl ketone and ethyl α-cyanoacetate, only small differences in the activities of the various catalysts were observed. These results, when translated to immobilized multipincer catalysts, imply that various para functionalities can be used for immobilization of the pincer−metal complexes without affecting the catalytic activity of the individual sites. The application of a number of shape-persistent nanosize (NCN−PdII)n complexes (7, n = 3; 8, n = 3; 9, n = 8; 10, n = 12) as homogeneous catalysts in the same Michael reaction, confirmed this expectation. For complexes 7, 8 and 9, the catalytic activity per PdII center was found to be the same as for the monopincer analogs. Only dodecakis(NCN−PdII) complex 10 showed an almost threefold enhancement in catalytic activity per PdII center, which is ascribed to the high catalyst concentration at the periphery of this material. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
53 citations
TL;DR: Theoretical studies of the unimolecular and water-assisted decomposition reactions of α-hydroxy hydroperoxides compounds produced during the isoprene ozonolysis have been investigated in this paper.
Abstract: Theoretical studies of the unimolecular and water-assisted decomposition reactions of the α-hydroxy hydroperoxides compounds produced during the isoprene ozonolysis have been investigated in this paper. Geometrical parameters of all the stationary points as well as energies and rate constants have been computed by means of several ab initio and DFT methods (B3LYP, CCSD(T), and G2M-RCC5 levels). Our calculations indicate that only the water-assisted decomposition of the α-hydroxy hydroperoxides could be active in the atmosphere. The main reaction products are predicted to be H2O2 plus methyl vinyl ketone (MVK) or methacroleine (MAC), depending on the particular α-hydroxy hydroperoxide considered. In both cases the reaction is endothermic by about 19 kcal mol-1.
52 citations
TL;DR: In this paper, the FeIII catalysed Michael reaction of β-oxo esters with methyl vinyl ketone (2a) and methyl acrylate (2b) as acceptors is investigated.
39 citations
TL;DR: In this paper, a new reaction condition for Michael addition of oximes onto activated olefins has been discovered using a catalytic amount of triphenylphosphine.
Abstract: A new reaction condition for Michael addition of oximes onto activated olefins has been discovered using a catalytic amount of triphenylphosphine. This is a first and milder alternative to classical base (hydroxide, alkoxide) catalyzed Michael addition of oximes. Various aldoximes la-h and ketoximes 2a-c (Figure 1) were reacted with different Michael acceptors such as ethyl acrylate, acrylonitrile, phenyl vinyl sulfone, methyl vinyl ketone, and 1-nitrocyclohex-1-ene to obtain the corresponding Michael adducts. About 35 different examples were attempted (Table 1 and Scheme 1); except in six cases where reactions did not produce desired products, yields varied from good to excellent. Reactions without triphenylphosphine did not proceed. A plausible mechanism of catalytic action in the present reactions is proposed (Figure 2).
32 citations
TL;DR: In this article, it was shown that exo-and endocyclic enamines are complementary with respect to the subsequent Michael reactions since they give stereocenters with opposite configurations.
30 citations
TL;DR: In this article, the synthesis of the new dienes N -substituted 2,3,4,5-tetrahydrobenzoxazol-2-ones 8a-8c is described, through a one-step convergent process from 1,2-cyclohexanedione (7a ) and corresponding isocyanates 2a-2c.
26 citations
TL;DR: In this paper, a liquid phase alkylation of phenol with 4-hydroxybutan-2-one was carried out in presence of H-beta zeolite modified by different techniques, such as thermal treatment, acid washing, ion exchange and surface passivation.
Abstract: Liquid phase alkylation of phenol with 4-hydroxybutan-2-one was carried out in presence of H-beta zeolite modified by different techniques, such as thermal treatment, acid washing, ion-exchange and surface passivation. Thermal- and acid-treated samples showed decrease in activity due to the removal of aluminium from the framework. The new Lewis acid sites generated by thermal treatment increased the selectivity of the O-alkylated product. Ion-exchange with cesium favoured the O-alkylated product due to the introduction of basic sites. Low temperature favoured the O-alkylated product, whereas high temperatures favoured the para alkylated product. When methyl vinyl ketone was used as the alkylating agent instead of 4-hydroxybutan-2-one, the change led to an increase in the selectivity of oligomers and other polyalkylated products. The increase in the concentration of the alkylating agents increased the selectivity of the O-alkylated product, due to the greater possibility of nucleophilic attack of phenoxide ion over the alkylating agents. The increase in the catalyst weight decreased the yield of O-alkylated product and increased the yield of para alkylated product. This demonstrated the conversion of the O-alkylated product into the para alkylated product. The studies on the rearrangement of the O-alkylated product which was synthesised separately also confirmed this fact. The para to O-alkylated product ratio observed over surface-passivated H-beta zeolite was the same as that observed over H-beta. This identity showed that the rearrangement takes place mainly inside the micropores.
TL;DR: In this paper, aroyl chlorides react readily with conjugated carbon-carbon double bonds in acrylates, acrylamides, methyl vinyl ketone and styrenes in a bis-acylation manner.
TL;DR: A detailed technical description of the system that was set up for long-term on-line measurements of isoprene and two of its major degradation products, methyl vinyl ketone and methacrolein is presented in order to provide a better understanding of the role of forest stands as a complex source of reactive trace gases into the troposphere and to elucidate the roles of forests as chemical reactors.
TL;DR: In this article, primary alcohols were converted into aldehydes by hydrogen transfer reaction using methyl vinyl ketone and ruthenium catalyst under microwave irradiation, which resulted in the recovery of the starting materials.
TL;DR: In this article, the rate constants for the OH + methyl vinyl ketone and methacrolein reactions have been measured in 2−5 Torr of He and over the temperature range 300−422 K using discharge-flow systems coupled with laser-induced fluorescence and resonance fluorescence detection of the OH radical.
Abstract: The rate constants for the OH + methyl vinyl ketone and OH + methacrolein reactions have been measured in 2−5 Torr of He and over the temperature range 300−422 K using discharge-flow systems coupled with laser-induced fluorescence and resonance fluorescence detection of the OH radical. The rate constant for the OH + methyl vinyl ketone reaction was found to be (1.73 ± 0.21) × 10-11 cm3 molecule-1 s-1 at 5 Torr. No significant pressure dependence was observed between 2 and 5 Torr at 300 K, but a pressure dependence of the rate constant was measured at temperatures between 328 and 422 K. At 328 K, the termolecular rate constant (k0) was measured to be (6.71 ± 2.65) × 10-28 cm6 molecule-2 s-1. An Arrhenius expression of k0 = (9.9 ± 7.6) × 10-30 exp[(1440 ± 300)/T] cm6 molecule-2 s-1 over the temperature range 328−422 K was obtained from a weighted linear least-squares fit of the k0 data versus temperature. Unlike the OH + methyl vinyl ketone reaction, a significant pressure dependence of the rate constant fo...
TL;DR: The triethylborane triggered intermolecular domino Michael-aldol reaction was described in this paper, where the triethyl-borane added in a Michael fashion to methyl vinyl ketone resulted in a vinylborane which further reacted with an aldehyde to give the aldol product in a one-pot process.
TL;DR: The isolated hexahydroderivatives were investigated and used as modifiers in the heterogeneous enantioselective hydrogenation of ethyl pyruvate and as catalysts in the Michael addition of Ethyl 2-oxocyclopentanecarboxylate to methyl vinyl ketone.
TL;DR: In this article, the Baylis-Hillman reaction of arylaldehydes with methyl vinyl ketone (MVK) was studied and the diadduct 2 can also be formed at the same time and the yield of 2 can reach to 55% if increasing the amount of MVK.
TL;DR: In this paper, a productive approach has been developed to spirocyclopropane-annelated 1,4-benzoxathiane 17 (85%), 1, 4-bromobenzoxazine 20−22 (56−88%) and 1, 6-ibenzoxazines 25, 26 (55−71%), through Michael additions of binucleophilic o-hydroxythiophenol 15, o-aminothiophenols 8 and ohydroxysulfanilides 23 onto methyl and tert-butyl 2-chloro-
TL;DR: In this paper, 1,4-Benzoquinones undergo cycloaddition reactions with electron rich alkenes in the presence of 10 mol% indium trichloride or 5 mol% iodine under mild conditions to afford the corresponding 2,3-dihydrobenzofurans in excellent yields with trans-selectivity.
Abstract: 1,4-Benzoquinones undergo smoothly [3 + 2] cycloaddition reactions with electron rich alkenes in the presence of 10 mol% indium trichloride or 5 mol% iodine under mild conditions to afford the corresponding 2,3-dihydrobenzofurans in excellent yields with trans-selectivity. Similarly, methyl vinyl ketone reacts with electron rich olefins to produce substituited trans-cyclobutane derivatives.
TL;DR: The Michael addition of a β,β-dimethyl substituted silyl ketene acetal [Me2CC(OMe)OSiMe3] to α-β-unsaturated ketones, namely, 2-cyclopentenone, 2cyclohexenone and isophorone, methyl vinyl ketone and mesityl oxide occurs smoothly in the presence of the nucleophilic catalyst, tetra-n-butyl ammonium bibenzoate (TBABB) in THF giving the corresponding 1,4
TL;DR: The Diels-Alder reaction rate constants of methyl vinyl ketone with cyclopentadiene and cyclohexadiene in the presence of a novel organotungsten catalyst, [P(2-py)(3)W(CO)(NO)(2)](2+), have been measured experimentally and modeled theoretically at several temperatures.
Abstract: The Diels−Alder reaction rate constants of methyl vinyl ketone with cyclopentadiene and cyclohexadiene in the presence of a novel organotungsten catalyst, [P(2-py)3W(CO)(NO)2]2+, have been measured experimentally and modeled theoretically at several temperatures. The uncatalyzed systems were also studied for direct comparison. When 0.0022 M of catalyst is present at room temperature, the rate constants were found to be approximately 5.3 and 5300 times higher than the corresponding uncatalyzed reactions for cyclopentadiene and cyclohexadiene systems, respectively. Experimental data suggested that the catalyst reduced the activation energies by 5−10 kcal/mol. However, the preexponential factors showed reduction of more than 3 orders of magnitude upon catalysis due to the entropic effects. The energy barriers and the rate constants of the uncatalyzed systems were accurately modeled by correlated electronic structure and dual-level variational transition state theory calculation. The calculated endo selectivi...
TL;DR: Despite the bulkiness of the neopentyl group, the isopropyl group with an alpha-branch has a better stereoinducing effect.
TL;DR: Reductive arylation of electron-deficient olefins: 4-(4-chlorophenyl)butan-2-one as discussed by the authors : semicarbazone
Abstract: Reductive arylation of electron-deficient olefins: 4-(4-chlorophenyl)butan-2-one
product: 4-(4-chlorophenyl)butan-2-one
product: semicarbazone
Keywords:
addition, to CC;
addition, to CC–CO and CC–CN;
arylation;
diazotization, preparation of diazonium salts;
reduction, miscellaneous;
P-chlorobenzenediazonium chloride, preparation of;
titanium trichloride;
methyl vinyl ketone;
addition funnels, with temperature-control jacket
TL;DR: In this paper, the copper-catalyzed conversion of exo-cyclic enamines with methyl vinyl ketone yields spirocyclic products 6a-c in a sequence of Michael and aldol reaction.
Abstract: The copper-catalyzed conversion of exo-cyclic enamines 4a-c with methyl vinyl ketone (2) yields spirocyclic products 6a-c in a sequence of Michael and aldol reaction. The application of the chiral auxiliary L-valine diethylamide results in the formation of quaternary stereocenters with high enantiomeric excess. The configuration of intermediate imine 5a is determined to be S. Thus, exo-cyclic enamines 4 yield S-configured spiroketones 6, whereas, as shown for spiroketone ent-6c, reaction of endo-cyclic enamines such as 1 generates the opposite configuration in the products applying the same auxiliary L-valine diethylamide 9.
TL;DR: In this paper, the enantiomeric purity of wieland-miescher ketone by NMR analysis with shift reagent was achieved by using shift reagents.
Abstract: (S)-8a-Methyl-3,4,8,8a-Tetrahydro-1,6(2H, 7H)-Naphthalenedione
product: (S)-8a-Methyl-3,4,8,8a-Tetrahydro-1,6(2H, 7H)-Naphthalenedione
intermediate: 2-methyl-2-(3-oxobutyl)-1,3-cyclohexanedione
reactant: 2-Methyl-1,3-cyclohexanedione
reactant: Methyl vinyl ketone, bp 34°C/120 mm
Keywords:
addition, to CC–CO and CC–CN;
annulation, carbocyclic-[6];
cyclization, condensation;
assay methods, of enantiomeric purity of wieland-miescher ketone by NMR analysis with shift reagent;
dimethyl sulfoxide;
shift reagents, chiral;
methyl vinyl ketone
TL;DR: In this paper, the selective formation of either regioisomer of both β-oxo (5a−c) and δ-oxon (4a −c) lactones from 3α−c was achieved by varying the reaction conditions.
TL;DR: In this paper, a weak lewis base such as imidazole can promote the reaction to give the normal Baylis-Hillman adduct under good yields under heterogeneous reaction conditions.
Abstract: In the Baylis-Hillman reaction of aldehydes with methyl vinyl ketone, we found that, in the presence of a stoichiometric amount of binol and silica gel(SiO2), a weak lewis base such as imidazole can promote the reaction to give the normal Baylis-Hillman adduct under good yields under heterogeneous reaction conditions.
TL;DR: In this article, the enantiomeric purity of l-(-)-proline by glc analysis was improved to CC-CO and CC-CN by adding an addition to CC CO and CCCN.
Abstract: ( + )-(7aS)-7a-Methyl-2,3,7,7a-tetrahydro-1 H-indene-1,5-(6H-dione
product: ( + )-(7aS)-7a-methyl-2,3,7,7a-tetrahydro-1 h-indene-1,5-(6H-dione
reactant: 140 mL (120.96 g, 1.72 mol) of methyl vinyl ketone
solvent: 188 mL of N,N-dimethyl-formamide
intermediate: 45.5 g (0.25 mol) of the 2-methyl-2-(3-oxobutyl)-1,3-cyclopentanedione
intermediate: ( + )-(3aS,7aS)-2,3,3a,4,7,7a-hexahydro-3a-hydroxy-7a-methyl-1H-indene-1,5(6H)-dione
Keywords:
addition, to CC-CO and CC–CN;
elimination, dehydration;
assay methods, of enantiomeric purity of l-(-)-proline by glc analysis;
N,N-dimethylformamide;
methyl vinyl ketone;
circulating bath, refrigerated
TL;DR: In this paper, the authors discuss the use of methyl vinyl ketone and Diethylaminotrimethylsilane for waste disposal in the context of waste disposal and waste disposal.
Abstract: (3R)-3, 7-dimethyl-2-(2-oxobutyl)-6-octenal
R-Citronellal
Methyl vinyl ketone
Diethylaminotrimethylsilane
Keywords:
1, 4-addition;
aldehydes;
methyl vinyl ketone;
5-ketoaldheydes;
2-cyclohene-1-one derivatives;
natural products;
acetonitrile;
silanes;
vinyl ketones;
waste disposal