- Catalytic Synthesis of 1 H-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers
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The metallo-radical activation of ortho-allylcarbonyl-aryl N-arylsulfonylhydrazones with the paramagnetic cobalt(II) porphyrin catalyst [CoII(TPP)] (TPP = tetraphenylporphyrin) provides an efficient and powerful method for the synthesis of novel 8-membered heterocyclic enol ethers. The synthetic protocol is versatile and practical and enables the synthesis of a wide range of unique 1H-2-benzoxocins in high yields. The catalytic cyclization reactions proceed with excellent chemoselectivities, have a high functional group tolerance, and provide several opportunities for the synthesis of new bioactive compounds. The reactions are shown to proceed via cobalt(III)-carbene radical intermediates, which are involved in intramolecular hydrogen transfer (HAT) from the allylic position to the carbene radical, followed by a near-barrierless radical rebound step in the coordination sphere of cobalt. The proposed mechanism is supported by experimental observations, density functional theory (DFT) calculations, and spin trapping experiments.
- De Bruin, Bas,De Zwart, Felix J.,Li, Zirui,Mathew, Simon,Wolzak, Lukas A.,Zhou, Minghui
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supporting information
p. 20501 - 20512
(2021/12/03)
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- Novel synthesis method of metribuzin intermediate
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The invention discloses a novel synthesis method of a metribuzin intermediate, wherein the intermediate triazinone of metribuzin is produced by using pinacolone (methyl tert-butyl ketone) as an initial raw material through reaction steps of chlorination, hydrolysis, oxidation, condensation and the like. According to the invention, the reaction conditions are mild, and the total yield reaches 92.4%; hydrogen peroxide is used as an oxidizing agent for replacing sodium hypochlorite, and the oxidation reaction is carried out at a room temperature, so that the operation is convenient, and the byproduct is water so as to avoid the discharge of pollutants such as salt-containing wastewater and the like in the production process; and after the reaction is finished, the intermediate and the catalyst are subjected to chromatographic separation so as to recycle the water phase containing the catalyst.
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- Stereocontrolled Synthesis of 1,4-Dicarbonyl Compounds by Photochemical Organocatalytic Acyl Radical Addition to Enals
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We report a visible-light-mediated organocatalytic strategy for the enantioselective acyl radical conjugate addition to enals, leading to valuable 1,4-dicarbonyl compounds. The process capitalizes upon the excited-state reactivity of 4-acyl-1,4-dihydropyridines that, upon visible-light absorption, can trigger the generation of acyl radicals. By means of a chiral amine catalyst, iminium ion activation of enals ensures a stereoselective radical trap. We also demonstrate how the combination of this acylation process with a second catalyst-controlled bond-forming event allows to selectively access the full matrix of all possible stereoisomers of the resulting 2,3-substituted 1,4-dicarbonyl products.
- Goti, Giulio,Bieszczad, Bartosz,Vega-Pe?aloza, Alberto,Melchiorre, Paolo
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supporting information
p. 1213 - 1217
(2019/01/04)
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- Method for synthesizing tetra-2,3-(5-t-tutylpyrazine)metalloporphyrin
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The invention relates to a method for synthesizing tetra-2,3-(5-t-tutylpyrazine)metalloporphyrin. The method comprises the following steps: using 3,3-dimethyl-2-butanone as a raw material, carrying out a selenizing reaction with selenium dioxide, and rectifying the product to obtain 3,3-dimethyl-2-oxobutryaldehyde; heating 3,3-dimethyl-2-oxobutryaldehyde obtained in the above step in the condition that 2,3-diamido-2-2-butene dinitrile, urea and metal chloride exist, and purifying the product to obtain the tetra-2,3-(5-t-tutylpyrazine)metalloporphyrin. According to the method, the tetra-2,3-(5-t-tutylpyrazine)metalloporphyrin can be obtained only through a two-step reaction of selenylation and synthesis and then through simple purification, the process is simple, and the product is controllable; the used raw materials are simple, and the cost is low; no poisonous or harmful waste product is produced in the middle process, so that the process of after-treatment is greatly reduced. The tetra-2,3-(5-t-tutylpyrazine)metalloporphyrin prepared in the invention is high in yield.
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Paragraph 0048; 0049; 0052; 0053; 0056; 0057
(2017/07/22)
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- Method for preparing a triazones (by machine translation)
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The invention discloses a method for preparing a triazones of: the two chlorine frequency alkone in the organic solvent and in the presence of the catalyst, in the 80 °C -140 ° C reaction under 1-3 hours, then post-processed to obtain compound I, compound I in the presence of an oxidizing agent and solvent, in 0 °C -40 ° C the oxidation reaction under 1-4 hours, a solution of trimethyl pyruvic acid obtained, the trimethyl pyruvic acid solution and sulfur under catalysis of carbazide in acid , in the 70 °C -90 ° C a cyclization reaction under 2-5 hours, then post-processed to obtain the triazones. The preparation method of this invention simple step, the raw materials are easy to obtain, the cost is low, does not produce high salt waste water, more consistent with the requirements of environmental protection, is suitable for industrial production, and, ultimately, to the yield of the product and the content is relatively high. (by machine translation)
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Paragraph 0034; 0036
(2017/01/23)
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- Synthesis and reactions of donor cyclopropanes: efficient routes to cis- and trans-tetrahydrofurans
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Abstract A detailed study on the synthesis and reactions of silylmethylcyclopropanes is reported. In their simplest form, these donor-only cyclopropanes undergo Lewis acid promoted reaction to give either cis- or trans-tetrahydrofurans, with the selectivity being reaction condition-dependant. The adducts themselves are demonstrated to be an important scaffold for structural diversification. The combination of a silyl-donor group in a donor-acceptor cyclopropane with novel acceptor groups is also discussed.
- Dunn, Jonathan,Dobbs, Adrian P.
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supporting information
p. 7386 - 7414
(2015/08/24)
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- One-pot three-component reactions of methyl ketones, phenols and a nucleophile: An expedient way to synthesize densely substituted benzofurans
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Three-component reactions of phenylglyoxal monohydrate, phenols, and indoles were developed with the aid of acid-catalyst, which produced various densely substituted benzofurans with good to excellent yields. On the basis of this observation, a one-pot, step-wise reaction was developed by using methyl ketones instead of using phenylglyoxal component in I2/DMSO system. At last, three-component reaction offered a useful way to synthesize densely substituted benzofurans starting from simple and easily available substrates. The indole component can be replaced by some other nucleophiles, such as 1,2,4-trimethoxybenzene and thiophenol.
- Cheng, Cheng,Liu, Changhui,Gu, Yanlong
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p. 8009 - 8017
(2015/12/31)
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- Three-component povarov reaction-heteroannulation with arynes: Synthesis of 5,6-dihydroindolo[1,2-a ]quinolines
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A reaction of 2-acyl substituted tetrahydroquinolines, prepared by Lewis acid-catalyzed three-component reaction of α-oxo aldehydes, anilines, and dienophiles, with in situ generated arynes afforded 5,6-dihydroindolo[1,2-a] quinolines in good to excellent
- Bunescu, Ala,Wang, Qian,Zhu, Jieping
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supporting information
p. 1756 - 1759
(2014/04/17)
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- New procedures for preparing 2,2,3,3-tetracyanocyclopropyl ketones
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New procedures were developed for preparing 2,2,3,3-tetracyanocyclopropyl ketones, based on reactions of substituted glyoxals with bromomalononitrile.
- Bardasov,Kayukova,Kayukov,Ershov,Nasakin
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experimental part
p. 1431 - 1434
(2010/01/05)
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- Synthesis and anti-protozoal activity of C2-substituted polyazamacrocycles
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A focused library of C2-substituted-1,4,7,10-tetraazacyclododecanes was synthesised and the compounds were tested for their ability to kill trypanosome and malaria parasites. Several compounds showed significant in vitro activity and were selectively active against the parasites over human embryonic kidney cells used as a counter screen.
- Reid, Caroline M.,Ebikeme, Charles,Barrett, Michael P.,Patzewitz, Eva-Maria,Mueller, Sylke,Robins, David J.,Sutherland, Andrew
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p. 2455 - 2458
(2008/09/21)
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- Catalytic asymmetric allylation of aldehydes using the chiral (salen)chromium(III) complexes
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The enantioselective addition of allylstannanes to glyoxylates and glyoxals, as well as simple aromatic and aliphatic aldehydes, catalyzed by chiral (salen)Cr(III) complexes, has been studied. The reaction proceeded smoothly for the reactive 2-oxoaldehydes and allyltributyltin in the presence of small amounts (1-2 mol %) of (salen)Cr(III)BF4 (1b) under mild, undemanding conditions. However, in the case of other simple aldehydes, the use of high-pressure conditions is required to obtain good yields. Classic chromium catalyst 1b, easily prepared from the commercially available chloride complex 1a, affords homoallylic alcohols usually in good yield and with enantiomeric purity of 50-79% ee. The stereochemical results are rationalized on the basis of the proposed model.
- Kwiatkowski, Piotr,Cha?adaj, Wojciech,Jurczak, Janusz
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p. 5116 - 5125
(2007/10/03)
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- Oxygen transfer from sulfoxide: Formation of aromatic aldehydes from dihalomethylarenes
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The conversion of dihalomethylarenes to the corresponding aldehydes is accomplished conveniently by using sulfoxides as the oxygen donor under neutral conditions.
- Li, Wei,Li, Jianchang,DeVincentis, Dianne,Mansour, Tarek S.
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p. 1071 - 1074
(2007/10/03)
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- Development of the Julia asymmetric epoxidation reaction. Part 2. Application of the oxidation to alkyl enones, enediones and unsaturated keto esters
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Polyleucine-based systems have been used to catalyse the asymmetric oxidation of a variety of alkyl enones 1-4, 9-14, an enynone 16 and a dienone 17 to afford the corresponding epoxides 5-8, 18-26 in good to excellent yield and optical purity. A range of enediones 30-32, 34 and one unsaturated keto ester 33 have also been epoxidised stereoselectively to afford optically active epoxides 35-39. The epoxidations were carried out with basic peroxide as the oxidant; the polyleucine catalyst was prepared from leucine N-carboxyanhydride using 1,3-diaminopropane, water (employing a humidity cabinet) or a polystyrene immobilised amine as the initiator. Preliminary mass spectral data on material derived from L-leucine and 1,3-diaminopropane (DAP-PLL) suggest that the catalyst consists of material that contains 22 ± 10 leucine residues.
- Kroutil, Wolfgang,Lasterra-Sanchez, M. Elena,Maddrell, Samuel J.,Mayon, Patrick,Morgan, Phillip,Roberts, Stanley M.,Thornton, Steven R.,Todd, Christine J.,Tueter, Melek
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p. 2837 - 2844
(2007/10/03)
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- Low-temperature photooxygenation of coelenterate luciferin analog synthesis and proof of 1,2-dioxetanone as luminescence intermediate
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Coelenterate luciferin analog having bulky tert-butyl group at the 2-position was suitable for studies on chemiluminescence under various conditions. Photooxygenation of the analog(s) at low temperature (-78°C) afforded luminous intermediates which were proved as peroxides by reduction with PPh3 with resultant loss of luminescence ability. In order to clarify these structures of accumulated luminous intermediates by means of 13C NMR, three 13C enriched analogs were synthesized at the 2, 3 and 5 positions of 3,7-dihydroimidazo[1,2-a]pyrazin-3-one skeleton in 99% enrichment with site-specificity. These 13C-enriched coelenterate luciferin analogs were photooxygenated at -78°C to form two peroxidic products as luminescent intermediates. Structures of these unstable intermediates were deduced by means of 13C NMR spectra at low temperature using substrates enriched at three sites by 13C. Photooxygenation in a mixture of CF3CD2OD and CD3OD as highly protic solvents afforded the dioxetanone and 2-hydroperoxide. These two peroxides emitted light independently at different temperatures either at 400 nm (neutral species) and/or 475 nm (anionic species) after diluting to 10-5 M in diglyme (DGM) containing acid or base.
- Usami, Ken,Isobe, Minoru
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p. 12061 - 12090
(2007/10/03)
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- Imidazopyridazines. XIII. Syntheses and Central Nervous System Activities of Some 2-Benzyl(phenethyl, biphenyl-4'-yl, 6'-methylnaphthalen-2'-yl, t-butyl and cyclohexyl)-3-methoxy(acylaminomethyl and dimethylaminomethyl)-6-(variously substituted)imidazopyridazines
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6-(Variously substituted)-3-methoxy(unsubstituted, dimethylaminomethyl, acetamidomethyl and benzamidomethyl)-2-benzyl(phenethyl, biphenyl-4'-yl, 6'-methylnaphthalen-2'-yl, t-butyl and cyclohexyl)imidazopyridazines have been prepared and examined for activity in the central nervous system.Of these, 2-benzyl-3-methoxy-6-(3'-methoxybenzylamino)imidazopyridazine (IC50 88 nM) bound most strongly to rat brain membrane.In general, the order of activity for groups at the 2-position was Ph>PhCH2>PhCH2CH2>C6H4Ph-p, 6'-methylnaphthalen-2'-yl, c-C6H11 or But.
- Barlin, Gordon B.,Davies, Les P.,Ireland, Stephen J.,Zhang, Jiankuo
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p. 1281 - 1300
(2007/10/02)
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- 6-(1-ACYL-1-HYDROXYMETHYL)PENICILLANIC ACID DERIVATIVES
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6-(1-Acyl-1-hydroxymethyl)penicillanic acid derivatives are useful as antibacterials and/or beta-lactamase inhibitors.
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- Structure-activity Relationship of Herbicidal 2,3-Dicyano-5-Substituted Pyrazines
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Sixty six 2,3-dicyano-5-substituted pyrazines were synthesized and their herbicidal activities against barnyard grass were measured in pot tests to clarify the relationship between chemical structure and activity.The activity of 59 derivatives was related parabolically to the hydrophobic substituent parameter at the 5-position of the pyrazine ring.
- Nakamura, Akira,Ataka, Toshiei,Segawa, Hirozo,Takeuchi, Yasutomo,Takematsu, Tetsuo
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p. 1555 - 1560
(2007/10/02)
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