Showing papers on "Methyl vinyl ketone published in 1995"
TL;DR: In this article, the effect of substitution of α,β-unsaturated aldehydes on the activity and selectivity of a series of platinum catalysts was investigated for the hydrogenation of these compounds.
213 citations
TL;DR: The results for methyl vinyl ketone and methacrolein were compared to previously reported measurements from this same location during the summer of 1990 as discussed by the authors, showing that isoprene levels were lower by ∼50% in 1992, while mixing ratios of the carbonyls were reduced by only ∼25%.
Abstract: Three oxygenated hydrocarbons were measured in ambient air above a rural forested site in western Alabama. Mixing ratios of methyl vinyl ketone (MVK), methacrolein (MACR), and 3-methyl furan were determined during a 3-week period in the summer of 1992. While the mean mixing ratio for methyl vinyl ketone was determined to be 740 parts per 1012 (ppt), the mean mixing ratio for methacrolein was 480 ppt. The results for methyl vinyl ketone and methacrolein are compared to previously reported measurements from this same location during the summer of 1990. Although isoprene levels were lower by ∼50% in 1992, mixing ratios of the carbonyls were reduced by only ∼25%. These differences are discussed in light of the changes that had occurred to the forest canopy in the time elapsed between the two measurement campaigns. Despite the differences observed during the 2 years, a consistent diurnal variability is observed for methyl vinyl ketone, relative to methacrolein, during both years. In addition to a weak correlation observed between the carbonyls and temperature, levels of MVK and MACR in air sampled from just above the forest canopy are influenced by the depth of the mixed layer. A third oxidation product of isoprene, 3-methyl furan, was identified and measured in ambient air. Mean daytime mixing ratios were estimated at 60 ppt. Nighttime levels were lower, averaging 40 ppt. Mixing ratios of 3-methyl furan were highly correlated with isoprene (R2 = 0.82), and during the day, were typically ∼2% of levels measured for isoprene.
89 citations
TL;DR: Asymmetric Michael reaction of N -methoxy- N -methyl-2-cyanopropionamide with vinyl ketones or acrolein in the presence of 0.1-1 mol% of a rhodium catalyst prepared in situ from Rh(acac)(CO) 2 and a trans-chelating chiral diphosphine ligand (S, S )-( R, R )-PhTRAP) gave optically active Michael adducts with high enantiomeric excesses (89-94%) in high yields.
57 citations
TL;DR: Some stable and lipophilic metal bis((perfluoroalkyl)sulfonyl)amides are prepared and employed as remarkable Lewis acid catalysts in the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone.
Abstract: Some stable and lipophilic metal bis((perfluoroalkyl)sulfonyl)amides are prepared and employed as remarkable Lewis acid catalysts in the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone.
39 citations
01 Dec 1995
35 citations
TL;DR: In this article, the room temperature rate constant for the reaction of the vinyl radical with molecular hydrogen has been determined by employing laser photolysis coupled to a kinetic-absorption spectroscopic technique and separately via a gas chromatographic product analysis technique.
33 citations
TL;DR: In this paper, semi-empirical calculations (AMI and PM3) have been used in the framework of the Self Consistent Reaction Field (SCRF) and supermolecule models in order to analyse solvent effects on the Diels-Alder reactions of cyclopentadiene and 2-methyl-l,3-butadiene (isoprene) with acrylonitrile, acrolein, methyl vinyl ketone, and methyl acrylate.
Abstract: Semi-empirical calculations (AMI and PM3) have been used in the framework of the Self-Consistent Reaction Field (SCRF) and supermolecule models in order to analyse solvent effects on the Diels-Alder reactions of cyclopentadiene and 2-methyl-l,3-butadiene (isoprene) with acrylonitrile, acrolein, methyl vinyl ketone, and methyl acrylate. Both SCRF and supermolecule models describe correctly the effect of the solvent on endo/exo selectivities. Supermolecule calculations are suitable to explain the influence of hydrogen bonding on activation barriers, but fail to explain the effect of strong HBD solvents on para/meta regioselectivity.
24 citations
TL;DR: In this article, it was shown that a 4-CF 3 substituent on the phenyl ring at C3 of the enone strongly promotes the cyclomanganation of chalcone molecules.
24 citations
TL;DR: Silyl nitronates of 2,2,2-trifluoronitroethane and of 1,1,1- trifluoro-2-nitropropane [SiMe3, SiMe2(tBu), siMe2CMe2-CHME2] were prepared and their reactions studied in this article.
Abstract: Silyl nitronates of 2,2,2-trifluoronitroethane and of 1,1,1-trifluoro-2-nitropropane [SiMe3, SiMe2(tBu), SiMe2CMe2-CHME2] were prepared and their reactions studied. – The TBDMS nitronate of the nitroethane is present at the (E) and (Z) isomer (2.3:1 at room temperature; EA = 9.3 kcal mol−1 for their isomerization). BU4NF-catalyzed silyl nitro aldol additions to aldehydes show reasonable selectivities for the formation of the syn diastereoisomers of 5–13 (a. 4:1; with the non-fluorinated analogs anti isomers prevailing!). The anti epimers (5–9, 12, 13, 17–20) in the trifluoromethyl series can be prepared by diastereoselective protonation of the corresponding O-silyl lithium nitronates (ca. 9:1, Scheme 3). Careful reduction of the NO2 groups (H2/Raney nickel) gives trifluoroamino alcohol derivatives (22–30, Scheme 4). –The trimethylsilyl nitronates are also used for 1,3-dipolar cycloadditions (to 1-hexene, styrene, methyl vinyl ketone, and acrylates) to give N-(silyloxy)isoxazolidines (2–40; Scheme 5). The configuration of the major products (2,3-cis, 3,5-trans) was derived from NMR measurements, X-ray structure determinations, and thermal equilibration studies. The major course of reactions was thus derived to be an exo approach of the dipolarophiles to the (Z)-silyl nitronates (Scheme 8).– Some conversions of the N-(silyloxy)isoxazolidines (treatment with acid, base, and Raney nickel) are also described (products 42–51).
23 citations
TL;DR: In this paper, the authors showed that the stereoselectivity of microbe-catalyzed reduction of ethyl 2-methyl-3-oxobutanoate to optically active 3-hydroxy-2-methylbutanoate can be controlled by the addition of methyl vinyl ketone to the rea...
Abstract: Stereoselectivity of microbe-catalyzed reduction of ethyl 2-methyl-3-oxobutanoate to optically active 3-hydroxy-2-methylbutanoate can be controlled by the addition of methyl vinyl ketone to the rea...
18 citations
TL;DR: Asymmetric Michael reactions of α-substituted β-keto esters with methyl vinyl ketone catalyzed by 10 mol% of sodium 2′-[2-(2methoxyethoxy)ethoxy]-1,1′-binaphthalen-2oxide gave the optically active adducts quantitatively in up to 64% enantiomeric excess.
Abstract: Asymmetric Michael reactions of α-substituted β-keto esters with methyl vinyl ketone catalyzed by 10 mol% of sodium 2′-[2-(2-methoxyethoxy)ethoxy]-1,1′-binaphthalen-2-oxide gave the optically active adducts quantitatively in up to 64% enantiomeric excess.
TL;DR: In this paper, the acid-catalysed (HCI) reactions of ferrocenethiol and ferrocene-1,1′-dithiol with isobutyl vinyl ether with the expected 1:1 and 1:2 adducts were characterized by 1H and 13C NMR spectroscopy.
TL;DR: The binary reagent PhSeClZnCl2 was found to be powerful for the stereocontrolled conversion of highly electrophilic olefins, such as maleate and fumarate esters, into the corresponding chloro phenylseleno derivatives in very high yields as mentioned in this paper.
TL;DR: In this paper, the addition of β-dioxygenato compounds to methyl vinyl ketone was catalysed by nickel (II) and cobalt(II) complexes with the polymerizable β-ketoesterato 2-(acetoacetoxy)ethyl methacrylate (AAEMA − ) under homogeneous and heterogeneous phases.
Abstract: The addition of β-dioxygenato compounds to methyl vinyl ketone was catalysed by nickel (II) and cobalt (II) complexes with the polymerizable β-ketoesterato 2-(acetoacetoxy)ethyl methacrylate (AAEMA − ) under homogeneous and heterogeneous phases. The homogeneous reactions were carried out using the soluble Ni(AAEMA) 2 and Co(AAEMA) 2 complexes whereas the heterogeneous catalytic tests were carried out using the copolymers obtained by reaction of M(AAEMA) 2 (M Ni or Co) with suitable acrylamides.
TL;DR: In this article, structural confirmation for adduct stereochemistry for this type of reaction is provided by an X-ray structural determination, in the presence of 5-10 mol% of Me3SiOSO2CF3(TMSOTf) in MeCN to provide trans-fused adducts arising via ionic Gassman-type Diels-Alder reactions.
Abstract: The trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBDMS) ethers of hexa-3,5-dien-1-ol react with cyclohexenones and an acyclic enone, methyl vinyl ketone (MVK), in the presence of 5–10 mol% of Me3SiOSO2CF3(TMSOTf) in MeCN to provide trans-fused adducts arising via ionic (Gassman-type) Diels–Alder reactions; structural confirmation for adduct stereochemistry for this type of reaction is provided by an X-ray structural determination.
TL;DR: In this paper, a two-laser pump-probe photolytic fragmentation fluorescence spectrometry of methyl vinyl ketone, methacrolein and crotonaldehyde is described.
TL;DR: In this article, magic-angle spinning (MAS) NMR and EPR were used in characterisation of the layered phase α-VOPO4·2H2O, and its n-butylammonium and n-βutylamine intercalates.
Abstract: Two magnetic resonance methods, magic-angle spinning (MAS) NMR and EPR, were used in the characterisation of the layered phase α-VOPO4·2H2O, and its n-butylammonium and n-butylamine intercalates. These revealed that intercalating molecules could replace water molecules in the coordination sphere of vanadium and that this influences the relative stability of the different oxidation states of the transition metal. Based on these findings, α-VOPO4·2H2O was tested for catalytic activity in the Diels–Alder cycloaddition of methyl vinyl ketone to cyclopentadiene. The layered phase displayed some catalytic activity with the ratio of products indicating a degree of shape selectivity. This catalysis was shown by EPR to involve electron donation to the layered host, with methyl vinyl ketone being intercalated (and activated) as a radical cation.
Journal Article•
TL;DR: In this article, the authors compared the performance of excess lithium gallium hydride with selected organic compounds containing representative functional groups under the standard conditions (diethyl ether, 0 in order to compare its reducing characteristics with lithium aluminum hydrides and lithium borohydride previously reported, and enlarge the scope of its applicability as a reducing agent.
Abstract: The approximate rates and stoichiometry of the reaction of excess lithium gallium hydride with selected organic compounds containing representative functional groups were examined under the standard conditions (diethyl ether, 0 in order to compare its reducing characteristics with lithium aluminum hydride and lithium borohydride previously reported, and enlarge the scope of its applicability as a reducing agent. Alcohols, phenol, and amines evolve hydrogen rapidly and quantitatively. However lithium gallium hydride reacts with only one active hydrogen of primary amine. Aldehydes and ketones of diverse structure are rapidly reduced to the corresponding alcohols. Conjugated aldehyde and ketone such as cinnamaldehyde and methyl vinyl ketone are rapidly reduced to the corresponding saturated alcohols. p-Benzoquinone is mainly reduces to hydroquinone. Caproic acid and benzoic acid liberate hydrogen rapidly and quantitatively, but reduction proceeds slowly. The acid chlorides and esters tested are all rapidly reduced to the corresponding alcohols. Alkyl halides and epoxides are reduced rapidly with an uptake of 1 equiv of hydride. Styrene oxide is reduced to give 1-phenylethanol quantitatively. Primary amides are reduced slowly. Benzonitrile consumes 2.0 equiv of hydride rapidly, whereas capronitrile is reduced slowly. Nitro compounds consumed 2.9 equiv of hydride, of which 1.9 equiv is for reduction, whereas azobenzene, and azoxybenzene are inert toward this reagent. Cyclohexanone oxime is reduced consuming 2.0 equiv of hydride for reduction at a moderate rate. Pyridine is inert toward this reagent. Disulfides and sulfoxides are reduced slowly, whereas sulfide, sulfone, and sulfonate are inert under these reaction conditions. Sulfonic acid evolves 1 equiv of hydrogen instantly, but reduction is not proceeded.
TL;DR: In this paper, Veratraldehyde was condensed with methyl 2-chloropropanoate to give a glycidic ester, which was then converted into 5-demethoxy porosin.
Abstract: Veratraldehyde was condensed with methyl 2-chloropropanoate to give a glycidic ester. This was hydrolyzed with aqueous sodium hydroxide and the resulting sodium salt was treated with lead(IV) tetraacetate to give 1-acetoxy-1-(3, 4-dimethoxyphenyl)propan-2-one (13). Condensation of 13 with dimethyl malonate, followed by acidic hydrolysis and sodium borohydride reduction afforded (2R*, 3S*, 4R*)-4-(3, 4-dimethoxyphenyl)-2-methoxycarbonyl-3-methyl-4-butanolide (7a). The γ-lactone 7a was then converted into 5'-demethoxyporosin (10) by means of a series of reactions : Michael reaction with methyl vinyl ketone, elimination of the methoxycarbonyl group, acetalization, allylation, deacetalization, and intramolecular aldol reaction. Introduction of a hydroxyl group at the C-5' position in 10, followed by methylation with diazomethane afforded racemic porosin. The synthetic porosin was further converted into 5-demethoxymegaphone acetate.
Patent•
28 Nov 1995
TL;DR: In this article, a 1,5-ketoaldehyde is produced by reacting an aliphatic aldehyde with an alpha,beta-unsaturated ketone in the presence of an aminosilane.
Abstract: PURPOSE:To produce a 1,5-ketoaldehyde from an inexpensive raw material by an easy reaction operation and a short synthetic path in high yield using a new process comprising the reaction of an aliphatic aldehyde with an alpha,beta-unsaturated ketone in the presence of an aminosilane. CONSTITUTION:A 1,5-ketoaldehyde is produced by reacting an aliphatic aldehyde (e.g. acetaldehyde or propylaldehyde) with an alpha,beta-unsaturated ketone (e.g. methyl vinyl ketone or 1-acetylcyclohexene) in the presence of an aminosilane [e.g. a compound of formula (R6 to R10 each is a substituted or unsubstituted hydrocarbon group) such as N-(trimethylsilyl)dimethylamine] preferably at 10-40 deg.C for generally 5-24hr. The amounts of the alpha,beta-unsaturated ketone and the aminosilane are preferably 0.9-1.5mol and 0.3-1mol based on the aldehyde, respectively.
Patent•
20 Jun 1995
TL;DR: In this article, a metal-containing copolymer of methyl vinyl ketone and methyl methacrylate with phosphorus trichloride and copper nitrate trihydrate was used to obtain a lens having near-infrared cutting performance.
Abstract: PURPOSE:To obtain a metal-containing resin useful for a lens having near- infrared cutting function by reacting a copolymer of methyl vinyl ketone and methyl methacrylate with phosphorus trichloride and adding polymethyl methacrylate and copper nitrate to the reactional product. CONSTITUTION:This metal-containing resin is produced by reacting (A) 2 pts.wt. of a copolymer obtained by compounding and copolymerizing (i) 2-28 pts.wt. of methyl vinyl ketone, (ii) 97-70 pts.wt. of methyl methacrylate and (iii) 0.5 pts.wt. of a polymerization initiator with (B) 0.1-0.6 pts.wt. of phosphorus trichloride and compounding 0.5 pts.wt. of the obtained copolymer with (C) 10 pts.wt. of polymethyl methacrylate and (D) 2-4 pts.wt. of copper nitrate trihydrate. A lens having near-infrared cutting performance can be manufactured by using the resin as the lens material.
TL;DR: Some stable and lipophilic metal bis((perfluoroalkyl)sulfonyl)amides are prepared and employed as remarkable Lewis acid catalysts in the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone.
Abstract: Some stable and lipophilic metal bis((perfluoroalkyl)sulfonyl)amides are prepared and employed as remarkable Lewis acid catalysts in the Diels-Alder reaction of cyclopentadiene with methyl vinyl ketone.
TL;DR: Silyl nitronates of 2,2,2-trifluoronitroethane and of 1,1,1- trifluoro-2-nitropropane [SiMe3, SiMe2(tBu), siMe2CMe2-CHME2] were prepared and their reactions studied in this paper.
Abstract: Silyl nitronates of 2,2,2-trifluoronitroethane and of 1,1,1-trifluoro-2-nitropropane [SiMe3, SiMe2(tBu), SiMe2CMe2-CHME2] were prepared and their reactions studied. – The TBDMS nitronate of the nitroethane is present at the (E) and (Z) isomer (2.3:1 at room temperature; EA = 9.3 kcal mol−1 for their isomerization). BU4NF-catalyzed silyl nitro aldol additions to aldehydes show reasonable selectivities for the formation of the syn diastereoisomers of 5–13 (a. 4:1; with the non-fluorinated analogs anti isomers prevailing!). The anti epimers (5–9, 12, 13, 17–20) in the trifluoromethyl series can be prepared by diastereoselective protonation of the corresponding O-silyl lithium nitronates (ca. 9:1, Scheme 3). Careful reduction of the NO2 groups (H2/Raney nickel) gives trifluoroamino alcohol derivatives (22–30, Scheme 4). –The trimethylsilyl nitronates are also used for 1,3-dipolar cycloadditions (to 1-hexene, styrene, methyl vinyl ketone, and acrylates) to give N-(silyloxy)isoxazolidines (2–40; Scheme 5). The configuration of the major products (2,3-cis, 3,5-trans) was derived from NMR measurements, X-ray structure determinations, and thermal equilibration studies. The major course of reactions was thus derived to be an exo approach of the dipolarophiles to the (Z)-silyl nitronates (Scheme 8).– Some conversions of the N-(silyloxy)isoxazolidines (treatment with acid, base, and Raney nickel) are also described (products 42–51).
TL;DR: In this article, the normal electron-demand Diels-Alder cycloaddition between cyclopentadiene and methyl vinyl ketone is inhibited by the cycloadduct, when catalyzed by kaolinite-supported zinc chloride.
Patent•
03 Feb 1995
TL;DR: In this article, a pheromone-like compound was obtained at a low cost by reacting (S)-1-nitro-2-propanol with t-butyldimethylsilyl chloride in a solvent such as DMF.
Abstract: PURPOSE:To obtain a compound useful as a synthetic intermediate for physiologically active substances such as pheromones. CONSTITUTION:This (S)-2-(t-butyldimethylsilyloxy)-1-nitropropane is expressed by the formula. The compound can be obtained at a low cost on a large scale by reacting (S)-1-nitro-2-propanol with t-butyldimethylsilyl chloride in a solvent such as DMF. Furthermore, this compound can be used as a raw material and subjected to the Michael addition reaction with methyl vinyl ketone in the presence of a base and subsequently the denitration hydrogenating reaction in tributylstannane/azobisisobutyronitrile system to afford optically active 6-(t- butyldimethylsilyloxy)-2-heptanone.
TL;DR: In this article, the Lewis acid catalyzed Diels-Alder reactions of dienyl phosphate esters 1 and 2 were examined, and the adducts were produced in accordance with the normal rules governing the Diels Alder addition.
Abstract: The Lewis acid catalyzed Diels–Alder reactions of dienyl phosphate esters 1 and 2 were examined. 2-Diethylphosphoryloxy-1,3-butadiene (1) was found to react with a variety of α,β-unsaturated carbonyl compounds under Lewis acid catalysis with excellent regioselectivity to give synthetically useful cyclohexene derivatives. The adducts were produced in accordance with the normal rules governing the Diels–Alder addition. In the presence of stannic chloride acyclic α,β-unsaturated ketones such as ethyl vinyl ketone and methyl vinyl ketone reacted rapidly with diene phosphate 1 to give exclusively the para-addition products 8 and 9 in excellent yields. When diene 1 was treated with the complex cyclic enone ester 14 in the presence of ferric chloride the single para-rule adduct 15 was obtained in good yield. The stannic chloride catalyzed Diels–Alder reactions of trans-2-diethylphosphoryloxy-1,3-pentadiene (2) were also studied. Diene phosphate 2 reacted efficiently with a number of acyclic α,β-unsaturated keton...