- Visible-Light-Induced Multicomponent Synthesis of γ-Amino Esters with Diazo Compounds
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A visible-light-induced multicomponent reaction of ethyl diazoacetate, diarylamines, and styrene-type alkenes is described. This novel 1,2-difunctionalization of alkenes can be readily achieved under a simple operation and mild conditions, affording γ-amino esters as major products. The reaction proceeds through the generation of carbon-centered radicals from diazo compounds by a visible-light-promoted proton-coupled electron transfer (PCET) process. The carbon radicals then add to diverse alkenes, delivering new carbon radical species, and the final products are formed with N-centered radicals via a radical-radical coupling.
- Ma, Na,Guo, Lin,Qi, Dan,Gao, Fei,Yang, Chao,Xia, Wujiong
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- Synthesis and antimicrobial activity of new 1,2,4-triazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, thiopyrane, thiazolidinone, and azepine derivatives
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4-oxo-4-phenylbutanehydrazide 3 was reacted with aryl or alkyl isothiocyanates to give the corresponding N-substituted-2-(4-oxo-4-phenylbutanoyl) hydrazine-1-carbothioamide 4a-c. Cyclization of thiosemicarbazides 4a-c with sodium hydroxide led to the formation of 3-(4-sub-5-thioxo-1,2,4-triazol-3-yl)-propanone 5a-c. Desulfurization of thiosemicarbazides 4a-c by mercuric oxide afforded 3-(5-(sub-amino)-1,3,4-oxadiazol-2-yl)-propanone 6a-c. The reaction of 4a-c with phosphorus oxychloride gave 3-(5-(sub-amino)-1,3,4-thiadiazol-2-yl)-propanone 7a-c. Treatment of 4a-c with ethyl-bromoacetate or α-bromopropionic acid gave N′-(3-sub-thiazolidin-2-ylidene)-butanehydrazide 8a-c and (N′-(3-sub-oxothiazolidin-2-ylidene)-butanehydrazide 9a-c. Chlorination of oxothiazolidine-hydrazide 9a-c by phosphorus oxychloride afforded N-(3-sub-4-oxothiazolidine)-butane-hydrazonoyl-chloride 10a-c. The reaction of 10a-c with mercaptoacetyl-chloride yielded 2-((4-benzoyl-thiopyrane) hydrazono)-3-sub-thiazolidinone 11a-c. Also, reacted of 10a-c with hydrazine hydrate afforded N″-(3-sub-oxothiazolidine)-butane-hydrazon-hydrazide 12a-c. The 3-sub-2-((pyridazine) hydrazono) thiazolidinone 13a-c was obtained by cyclization of 12a-c via refluxing in DMF. The reaction and cyclized of 9a-c with chloroacetyl-chloride in ethanolic KOH afforded 1-((3-sub-4-oxothiazolidine) amino)-azepine-dione 14a-c. The chemical structures of the new compounds have been confirmed by diverse spectroscopy analyses such as IR, NMR, MS, and elemental analysis. The synthesized compounds were tested for their antimicrobial activity and these compounds were considered (Pyridazin-hydrazono-thiazolidinone 13a-c, oxothiazolidin-azepinedione 14a-c, N-thiazolidin-hydrazon-hydrazide 12a-c, and thiopyran-hydrazono-thiazolidinone 11a-c) the most effective as antimicrobial activity.
- Abu-Hashem, Ameen Ali
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- Visible Light Induced Br?nsted Acid Assisted Pd-Catalyzed Alkyl Heck Reaction of Diazo Compounds and N-Tosylhydrazones
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A mild visible light-induced palladium-catalyzed alkyl Heck reaction of diazo compounds and N-tosylhydrazones is reported. A broad range of vinyl arenes and heteroarenes with high functional group tolerance, as well as a range of different diazo compounds, can efficiently undergo this transformation. This method features Br?nsted acid-assisted generation of hybrid palladium C(sp3)-centered radical intermediate, which allowed for new selective C?H functionalization protocol.
- Dubrovina, Anastasiia,Gevorgyan, Vladimir,Kvasovs, Nikita,Zhang, Ziyan
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supporting information
(2021/11/30)
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- Palladium/Zinc Co-Catalyzed Asymmetric Hydrogenation of γ-Keto Carboxylic Acids
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A palladium-catalyzed asymmetric hydrogenation of levulinic acid has been successful developed by using Zn(OTf)2 as co-catalyst. The present method not only has provided a strategy in the palladium-catalyzed asymmetric hydrogenation of ketone, but also allowed the preparation of a wide range of chiral γ-valerolactones in good yields with excellent enantioselectivities.
- Zhang, Keyang,Zhang, Xuexin,Chen, Jingchao,Liu, Zixiu,Pan, Chunxiang,Zhu, Yuanbin,Wu, Shiyuan,Fan, Baomin
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supporting information
p. 1229 - 1232
(2021/05/03)
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- Copper catalyzed C(sp3)-H bond alkylation via photoinduced ligand-to-metal charge transfer
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Utilizing catalytic CuCl2 we report the functionalization of numerous feedstock chemicals via the coupling of unactivated C(sp3)-H bonds with electron-deficient olefins. The active cuprate catalyst undergoes Ligand-to-Metal Charge Transfer (LMCT) to enable the generation of a chlorine radical which acts as a powerful hydrogen atom transfer reagent capable of abstracting strong electron-rich C(sp3)-H bonds. Of note is that the chlorocuprate catalyst is an exceedingly mild oxidant (0.5 V vs SCE) and that a proposed protodemetalation mechanism offers a broad scope of electron-deficient olefins, offering high diastereoselectivity in the case of endocyclic alkenes. The coupling of chlorine radical generation with Cu reduction through LMCT enables the generation of a highly active HAT reagent in an operationally simple and atom economical protocol.
- Treacy, Sean M.,Rovis, Tomislav
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supporting information
p. 2729 - 2735
(2021/03/01)
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- Synthesis of new pyrazoles, oxadiazoles, triazoles, pyrrolotriazines, and pyrrolotriazepines as potential cytotoxic agents
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4-Oxo-4-phenylbutanehydrazide (1) reacted with many active methylene reagents such as acetylacetone, diethylmalonate, ethylacetoacetate, ethylcyanoacetate, benzoyl-acetonitrile, and malononitrile under neat conditions to afford the corresponding pyrazoles (2–7), also, treatment of butanehydrazide (1) with electrophilic reagents as triethylorthoformate, dimethylformamide-dimethylacetal, acetic anhydride, and carbon disulfide to give 1,3,4-oxadiazoles (8,10,11) and N′-acetyl-butanehydrazide (9). Reacted of butanehydrazide (1) with potassium thiocyanate gave 1,2,4-triazoles (12). Similarly, treatment of (1) with chloroacetamide gave 1,2,4-triazinones (13). The pyrrolotriazinones (14) was obtained by cyclization of (13). Also, butanehydrazide (1) was utilized as a starting material for the synthesized of new Schiff bases as N′-(4-sub-benzylidene)-phenylbutane-hydrazide (15a-c), which are used as an initiative to prepare new compounds such as 1,2,4-triazepinones (16a-c), pyrrolotriazepinones (17a-c), 1,2,4-triazines (18a-c), and pyrrolotriazines (19a-c) by reacted of (15a-c) with each chloroacetamide or formamide. The chemical structure of the newly prepared compounds was determined through the spectrum data, including IR, NMR, and MS. The prepared compounds were tested for their in vitro antitumor activities. The compounds 17a-c, 16a-c, and 19a-c displayed activity against several types of cancer cell lines.
- Abu-Hashem, Ameen Ali
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p. 805 - 821
(2021/01/12)
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- Synthesis of Unsymmetrical 1,4-Dicarbonyl Compounds by Photocatalytic Oxidative Radical Additions
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Herein we report a photocatalytic oxidative radical addition reaction for the synthesis of unsymmetrical 1,4-dicarbonyl compounds. This reaction utilizes a desulfurization process to generate electrophilic radicals, which add to α-halogenated alkenes and undergo further oxidation to deliver 1,4-dicarbonyl compounds. This mild and highly efficient method provides a valuable alternative to known strategies.
- Dong, Ya,Li, Ruining,Zhou, Junliang,Sun, Zhankui
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p. 6387 - 6390
(2021/08/23)
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- Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water
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A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water. This journal is
- Li, Tiejun,Peng, Henian,Tang, Wenjun,Tian, Duanshuai,Xu, Guangqing,Yang, He
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p. 4327 - 4337
(2021/05/31)
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- Borane-Catalyzed, Chemoselective Reduction and Hydrofunctionalization of Enones Enabled by B-O Transborylation
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The use of stoichiometric organoborane reductants in organic synthesis is well established. Here these reagents have been rendered catalytic through an isodesmic B-O/B-H transborylation applied in the borane-catalyzed, chemoselective alkene reduction and formal hydrofunctionalization of enones. The reaction was found to proceed by a 1,4-hydroboration of the enone and B-O/B-H transborylation with HBpin, enabling catalyst turnover. Single-turnover and isotopic labeling experiments supported the proposed mechanism of catalysis with 1,4-hydroboration and B-O/B-H transborylation as key steps.
- Nicholson, Kieran,Langer, Thomas,Thomas, Stephen P.
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supporting information
p. 2498 - 2504
(2021/04/13)
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- Reduction of Activated Alkenes by PIII/PV Redox Cycling Catalysis
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The carbon–carbon double bond of unsaturated carbonyl compounds was readily reduced by using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl-substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction. In total, 25 alkenes and two alkynes were hydrogenated to the corresponding alkanes in excellent yields of up to 99 %. Notably, less active poly(methylhydrosiloxane) could also be utilized as the terminal reductant. Mechanistic investigations revealed the phosphane as the catalyst resting state and a protonation/deprotonation sequence as the crucial step in the catalytic cycle.
- Longwitz, Lars,Werner, Thomas
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supporting information
p. 2760 - 2763
(2020/02/05)
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- Direct Synthesis of Chiral NH Lactams via Ru-Catalyzed Asymmetric Reductive Amination/Cyclization Cascade of Keto Acids/Esters
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Lactams with a stereogenic center adjacent to the N atom have existed in many medicinal agents and bioactive alkaloids. Herein we report a broadly applicable synthesis of enantioenriched NH lactams through a one-pot asymmetric reductive amination/cyclization sequence of easily available keto acids/esters. Such cascade processes alleviate the demand for protecting group manipulations as well as intermediate purification. This strategy is capable of constructing enantioenriched lactams and benzo-lactams of a five-, six-, or seven-membered ring in generally high yield and with excellent enantioselectivities (up to 97% ee). Scalable and concise syntheses of key drug intermediates have further displayed the importance of this methodology.
- Shi, Yongjie,Tan, Xuefeng,Gao, Shuang,Zhang, Yao,Wang, Jingxin,Zhang, Xumu,Yin, Qin
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supporting information
p. 2707 - 2713
(2020/03/30)
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- Synthesis of 1,2,4-triazolopyridazines, isoxazolofuropyridazines, and tetrazolopyridazines as antimicrobial agents
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Through current and previous researches, it was found that the derivatives of pyridazine, isoxazole, tetrazole, quinazoline, hydrazinyl, and 1,2,4-triazole have many pharmacological activities. Thus, a series of novel furopyridazinones (7), isoxazolopyridazine (8), sub-benzylidene-furopyridazinones (9a-c), isoxazolofuropyridazines (10a-c), 3-chloro-(pyridin-4-ylmethylene)-dihydropyridazines (11), tetrazolopyridazines (12), pyridazinoquinazolinones (13), piperazinyl/morpholino-pyridazines (14a,b), hydrazinyl-pyridazines (15), and 1,2,4-triazolo-pyridazines (16a,b) in good yields (72%-90%) were synthesized from substituted ethyl 4-oxo-4-phenylbutanoate (2), 6-phenyl-4,5-dihydropyridazinone (3), and 6-phenyl-4-(pyridin-4-ylmethylene)-4,5-dihydropyridazinone (4) as beginning materials. All the chemical structures of the new compounds have been demonstrated by different spectroscopy analyses such as infrared, NMR, mass spectrum, and elemental analysis. Also, the activities of the newly prepared compounds were tested against many types of bacteria and fungi in vitro. Hence, 1,2,4-triazolopyridazines (16a,b), isoxazolofuropyridazines (10a-c), tetrazolopyridazines (12), Piperazinyl/morpholinyl-pyridazines (14a,b) displayed the most efficient antimicrobial activities compared with the cefotaxime sodium and nystatin as standard drugs.
- Abu-Hashem, Ameen A.,Fathy, Usama,Gouda, Moustafa A.
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p. 3461 - 3474
(2020/08/03)
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- Atmospheric Oxygen Mediated Radical Hydrothiolation of Alkenes
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A mild, metal-free, atmospheric oxygen-mediated radical hydrothiolation of alkenes (and alkyne) is reported. A variety of sulfur containing motifs including alkanethiols, thiophenols and thioacids undergo an atmospheric oxygen-mediated radical hydrothiolation reaction with a plethora of alkenes in good yield with excellent functional group compatibility, typically with short reaction times to furnish a range of functionalized products. Biomolecules proved tolerant to the conditions and the procedure is robust and easily executable requiring no specialized equipment. Concise mechanistic studies confirm the process proceeds through radical intermediates in a thiol-ene reaction manifold. The methodology offers an efficient “green” approach for thiol-ene mediated “click” ligation and a milder alternative to thermally initiated hydrothiolation processes.
- McCourt, Ruairí O.,Scanlan, Eoin M.
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supporting information
p. 15804 - 15810
(2020/10/26)
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- Radical-Mediated Strategies for the Functionalization of Alkenes with Diazo Compounds
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One of the most common reactions of diazo compounds with alkenes is cyclopropanation, which occurs through metal carbene or free carbene intermediates. Alternative functionalization of alkenes with diazo compounds is limited, and a methodology for the addition of the elements of Z-CHR2 (with Z = H or heteroatom, and CHR2 originates from N2 CR2) across a carbon-carbon double bond has not been reported. Here we report a novel reaction of diazo compounds utilizing a radical-mediated addition strategy to achieve difunctionalization of diverse alkenes. Diazo compounds are transformed to carbon radicals with a photocatalyst or an iron catalyst through PCET processes. The carbon radical selectively adds to diverse alkenes, delivering new carbon radical species, and then forms products through hydroalkylation by thiol-assisted hydrogen atom transfer (HAT), or forms azidoalkylation products through an iron catalytic cycle. These two processes are highly complementary, proceed under mild reaction conditions, and show high functional group tolerance. Furthermore, both transformations are successfully performed on a gram-scale, and diverse γ-amino esters, γ-amino alcohols, and complex spirolactams are easily prepared with commercially available reagents. Mechanistic studies reveal the plausible pathways that link the two processes and explain the unique advantages of each.
- Su, Yong-Liang,Liu, Geng-Xin,Liu, Jun-Wen,Tram, Linh,Qiu, Huang,Doyle, Michael P.
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supporting information
p. 13846 - 13855
(2020/09/21)
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- Acyl radicals from α-keto acids using a carbonyl photocatalyst: Photoredox-catalyzed synthesis of ketones
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Acyl radicals have been generated from α-keto acids using inexpensive and commercially available 2-chloro-thioxanthen-9-one as the photoredox catalyst under visible light illumination. These reactive species added to olefins or coupled with aryl halides via a bipyridylstabilized Ni(II) catalyst, enabling easy access to a diverse range of ketones. This reliable, atom-economical, and eco-friendly protocol is compatible with a wide range of functional groups.
- Zhu, Da-Liang,Wu, Qi,Young, David James,Wang, Hao,Ren, Zhi-Gang,Li, Hong-Xi
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supporting information
p. 6832 - 6837
(2020/10/12)
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- 1-butyl-3-methylimidazolium bromide as a solvent and precatalyst for stetter reaction
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Stetter reaction between aromatic aldehydes and acrylonitrile/ethyl acrylate performing in [Bmim]Br in the presence of NaOH is described. N-Heterocyclic carbene (NHC) generates in situ is shown to be an efficient catalyst. Benzoin condensation also occured as side reaction.
- Phungpis, Baramee,Hahnvajanawong, Viwat
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p. 2028 - 2032
(2020/09/02)
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- Nickel-Catalyzed Transformation of Diazoacetates to Alkyl Radicals Using Alcohol as a Hydrogen Source
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A nickel-catalyzed transformation of diazoacetates to α-carbonyl methylene radicals has been disclosed in the presence of hyperoxide using ethanol as a hydrogen source and solvent. This strategy is successfully applied in the formation of indolin-2-ones or 1,4-dicarbonyl compounds from acrylamides or enamides in moderate to good yields. These reactions undergo radical addition onto C-C double bonds followed by a cyclization/oxidation or an oxidation/hydrolysis process, respectively.
- Zhao, Jingjing,Li, Pan,Xu, Yaohua,Shi, Yixin,Li, Fuwei
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supporting information
p. 9386 - 9390
(2019/11/28)
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- Photoredox Reaction of 2-Mercaptothiazolinium Salts with Silyl Enol Ethers
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A method for the generation of free radicals from thiazolinium salts upon photocatalytic reduction is described. The thiazolinium salts are generated by treatment with methyl triflate of 2-mercaptothiazolines, which can be readily obtained from alkyl bromides and tosylates via a nucleophilic substitution reaction or by hydrothiolation of alkenes. Silyl enol ethers were used to trap the radicals, furnishing ketones after successive single-electron oxidation and elimination of the silyl cation.
- Zemtsov, Artem A.,Ashirbaev, Salavat S.,Levin, Vitalij V.,Kokorekin, Vladimir A.,Korlyukov, Alexander A.,Dilman, Alexander D.
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- One-Pot Synthesis of 2,5-Disubstituted Furans through In Situ Formation of Allenes and Enolization Cascade
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A one-pot synthesis of 2,5-disubstituted furans from γ-ketoacids is reported. In situ formation of allenoates by action of chloroformate on carboxylic acid following by enolization of ketone affords furan derivatives by cyclization. The reaction was extended to a wide scope of ketoacids and phosphonium salts. This methodology was applied on levulinic acid and derivatives, one of the biosourced platform chemicals.
- Bernhard, Yann,Gilbert, Joachim,Bousquet, Till,Favrelle-Huret, Audrey,Zinck, Philippe,Pellegrini, Sylvain,Pelinski, Lydie
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supporting information
p. 7870 - 7873
(2019/12/24)
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- A process for preparing γ - ketone carbonyl compounds
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The present invention discloses a gamma-ketone carbonyl compound preparation method, wherein in the presence of an oxidizing agent, a styrene compound and ethyl diazoacetate are adopted as reactants, copper or a copper compound is adopted as a catalyst, DABCO is adopted as an alkali, and a free radical reaction is performed in a polar solvent isopropyl alcohol to obtain the product gamma-ketone carbonyl compound. According to the method of the present invention, the reaction activity of the catalyst is high, the reaction conditions are mild, the substrate application range is wide, the post-treatment is convenient, the yield of the target product is high, the preparation process is simple, and the sources of the used raw materials are wide.
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Paragraph 0026-0028; 0030-0052; 0054-0072; 0074-0104
(2018/07/30)
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- Enantioselective Halo-oxy- and Halo-azacyclizations Induced by Chiral Amidophosphate Catalysts and Halo-Lewis Acids
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Catalytic enantioselective halocyclization of 2-alkenylphenols and enamides have been achieved through the use of chiral amidophosphate catalysts and halo-Lewis acids. Density functional theory calculations suggested that the Lewis basicity of the catalyst played an important role in the reactivity and enantioselectivity. The resulting chiral halogenated chromans can be transformed to α-Tocopherol, α-Tocotrienol, Daedalin A and Englitazone in short steps. Furthermore, a halogenated product with an unsaturated side chain may provide polycyclic adducts under radical cyclization conditions.
- Lu, Yanhui,Nakatsuji, Hidefumi,Okumura, Yukimasa,Yao, Lu,Ishihara, Kazuaki
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supporting information
p. 6039 - 6043
(2018/05/14)
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- α-Alkylation of ketimines using visible light photoredox catalysis
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A novel α-alkylation of N-diphenylphosphinoyl ketimines with α-bromocarbonyl compounds has been accomplished using visible light photoredox catalysis. The reaction proceeds under remarkably mild conditions: at 35 °C, in 20 hours, under blue light irradiation (1 W), in the presence of a tertiary amine and catalytic amounts of Ru- and Ni-based complexes. Chemoselective transformation of the products provides access to 1,4-dicarbonyl compounds, protected GABA analogues and γ-lactams.
- Franchino, Allegra,Rinaldi, Antonia,Dixon, Darren J.
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p. 43655 - 43659
(2017/09/22)
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- Photoredox-Catalyzed Hydroacylation of Olefins Employing Carboxylic Acids and Hydrosilanes
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A hydroacylation reaction of alkenes has been achieved employing readily available carboxylic acids as the acyl source and hydrosilanes as a hydrogen source via photoredox catalysis. The combination of both single electron transfer and hydrogen atom transfer steps has dramatically expanded new applications of carboxylic acids in organic synthesis. The protocol also features extremely mild conditions, broad substrate scope, and good functional group tolerance, affording a novel and convenient approach to hydroacylation of alkenes.
- Zhang, Muliang,Ruzi, Rehanguli,Xi, Junwei,Li, Nan,Wu, Zhongkai,Li, Weipeng,Yu, Shouyun,Zhu, Chengjian
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supporting information
p. 3430 - 3433
(2017/07/15)
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- Phenyl substituted pyridazine structure unit containing compounds and methods for their preparation and use
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The invention discloses compounds containing phenyl substituted pyridazine structural unit, and a preparation method and application thereof. The structural general formula of the compounds containing phenyl substituted pyridazine structural unit is disclosed as Formula I. The compounds disclosed as Formula I have proper nuclear magnetic detection; and in order to solve the problems of less research on near-infrared materials and deficiency in high-efficiency high-stability near-infrared luminescent materials at present stage, the invention provides a series of near-infrared luminescent materials containing phenyl substituted pyridazine structure. The compounds have the advantages of accessible raw material, simple preparation process and high overall yield, and have important application value for researching development and application of near-infrared materials.
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Paragraph 0085-0086
(2016/11/17)
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- Cobalt(i)-catalysed CH-alkylation of terminal olefins, and beyond
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Cobalester, a natural nontoxic vitamin B12 derivative, was found to catalyse unusual olefinic sp2 C-H alkylation with diazo reagents as a carbene source instead of the expected cyclopropanation.
- Giedyk, Maciej,Goliszewska, Katarzyna,ó Proinsias, Keith,Gryko, Dorota
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supporting information
p. 1389 - 1392
(2016/01/25)
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- Asymmetric Catalysis with Organic Azides and Diazo Compounds Initiated by Photoinduced Electron Transfer
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Electron-acceptor-substituted aryl azides and α-diazo carboxylic esters are used as substrates for visible-light-activated asymmetric α-amination and α-alkylation, respectively, of 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium-based Lewis acid in combination with a photoredox sensitizer. This novel proton- and redox-neutral method provides yields of up to 99% and excellent enantioselectivities of up to >99% ee with broad functional group compatibility. Mechanistic investigations suggest that an intermediate rhodium enolate complex acts as a reductive quencher to initiate a radical process with the aryl azides and α-diazo carboxylic esters serving as precursors for nitrogen and carbon-centered radicals, respectively. This is the first report on using aryl azides and α-diazo carboxylic esters as substrates for asymmetric catalysis under photoredox conditions. These reagents have the advantage that molecular nitrogen is the leaving group and sole byproduct in this reaction.
- Huang, Xiaoqiang,Webster, Richard D.,Harms, Klaus,Meggers, Eric
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supporting information
p. 12636 - 12642
(2016/10/07)
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- Chiral Surfactant-Type Catalyst: Enantioselective Reduction of Long-Chain Aliphatic Ketoesters in Water
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A series of amphiphilic ligands were designed and synthesized. The rhodium complexes with the ligands were applied to the asymmetric transfer hydrogenation of broad range of long-chained aliphatic ketoesters in neat water. Quantitative conversion and excellent enantioselectivity (up to 99% ee) was observed for α-, β-, γ-, δ- and ε-ketoesters as well as for α- and β-acyloxyketone using chiral surfactant-type catalyst 2. The CH/π interaction and the strong hydrophobic interaction of long aliphatic chains between the catalyst and the substrate in the metallomicelle core played a key role in the catalytic transition state. Synergistic effects between the metal-catalyzed site and the hydrophobic microenvironment of the core in the micelle contributed to high stereoselectivity. (Chemical Equation Presented).
- Lin, Zechao,Li, Jiahong,Huang, Qingfei,Huang, Qiuya,Wang, Qiwei,Tang, Lei,Gong, Deying,Yang, Jun,Zhu, Jin,Deng, Jingen
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p. 4419 - 4429
(2015/05/13)
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- Ring Expansion of Epoxides under Br?nsted Base Catalysis: Formal [3+2] Cycloaddition of β,γ-Epoxy Esters with Imines Providing 2,4,5-Trisubstituted 1,3-Oxazolidines
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A novel ring-expansion reaction of epoxides under Br?nsted base catalysis was developed. The formal [3+2] cycloaddition reaction of β,γ-epoxy esters with imines proceeds in the presence of triazabicyclodecene (TBD) as a superior Br?nsted base catalyst to afford 2,4,5-trisubstituted 1,3-oxazolidines in a highly diastereoselective manner. This reaction involves the ring opening of the epoxides with the aid of the Br?nsted base catalyst to generate α,β-unsaturated esters having an alkoxide at the allylic position, which would formally serve as a synthetic equivalent of the 1,3-dipole, followed by a cycloaddition reaction with imines in a stepwise fashion. This methodology enables the facile synthesis of enantioenriched 1,3-oxazolidines from easily accessible enantioenriched epoxides.
- Kondoh, Azusa,Odaira, Kenta,Terada, Masahiro
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p. 11240 - 11244
(2016/07/06)
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- Cu-based carbene involved in a radical process: A new crossover reaction to construct γ-peroxy esters and 1,4-dicarbonyl compounds
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Through merging Cu-based carbenes in a radical process, a novel crossover reaction has been successfully established, leading to the facile and efficient syntheses of various γ-peroxy esters and 1,4-dicarbonyl compounds. Considering that both Cu-based carbene complexes and radicals are extremely reactive, and therefore exist only in extraordinarily low concentrations, the high selectivity of this coupling reaction is unusual.
- Jiang, Jiewen,Liu, Jiajun,Yang, Ling,Shao, Ying,Cheng, Jiang,Bao, Xiaoguang,Wan, Xiaobing
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supporting information
p. 14728 - 14731
(2015/10/05)
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- Decarboxylative 1,4-Addition of α-Oxocarboxylic Acids with Michael Acceptors Enabled by Photoredox Catalysis
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Enabled by iridium photoredox catalysis, 2-oxo-2-(hetero)arylacetic acids were decarboxylatively added to various Michael acceptors including α,β-unsaturated ester, ketone, amide, aldehyde, nitrile, and sulfone at room temperature. The reaction presents a new type of acyl Michael addition using stable and easily accessible carboxylic acid to formally generate acyl anion through photoredox-catalyzed radical decarboxylation.
- Wang, Guang-Zu,Shang, Rui,Cheng, Wan-Min,Fu, Yao
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supporting information
p. 4830 - 4833
(2015/10/12)
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- Synthesis of the novel tetrahydropyrazolo[3,4- c ]pyridin-5-one scaffold
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We report an efficient synthesis of the novel 1,4,6,7-tetra-hydropyrazolo[3,4-c]pyridin-5-one scaffold with the potential for incorporation of alkyl or aryl substituents at the C-3 and N-6 positions. The route utilises a Dieckmann condensation to install the lactam ring, followed by a hydrazine cyclisation to build the fused pyrazole ring.
- Howe, Nicholas J.,Blades, Kevin,Lamont, Gillian M.
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supporting information
p. 228 - 232
(2015/03/03)
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- Biotransformation of aromatic ketones and ketoesters with the non-conventional yeast Pichia glucozyma
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The non-conventional yeast Pichia glucozyma CBS 5766 has been used for the biotransformation of different aromatic ketones and ketoesters. The growth and biotransformation conditions were optimised for the reduction of acetophenone and under optimised conditions, propiophenone, butyrophenone and valerophenone were reduced to the corresponding (S)-alcohols with high yields and enantioselectivity. Ketoreductase(s) of Pichia glucozyma showed high catalytic activities also towards aromatic β- and γ-ketoesters, being often competitive with esterase(s). These concurrent activities allowed for the preparation of hydroxyesters, hydroxyacids and lactones often in a very selective manner.
- Contente, Martina Letizia,Molinari, Francesco,Zambelli, Paolo,De Vitis, Valerio,Gandolfi, Raffaella,Pinto, Andrea,Romano, Diego
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supporting information
p. 7051 - 7053
(2015/02/02)
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- Benzoin condensation and stetter reaction catalysed by N,N-dimethylbenzimidazolium iodide in [Bmim][OH]
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N,N-Dimethylbenzimidazolium iodide catalysed benzoin condensation and Stetter reaction in 1-butyl-3-methylimidazolium hydroxide [bmim][OH] which acts as a basic catalyst as well as a solvent for the reactions are described. The recycled reaction media containing benzimidazolium salt can be reused for several times without significant loss of efficiency.
- Phungpis, Baramee,Hahnvajanawong, Viwat,Theramongkol, Parinya
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p. 933 - 939
(2015/02/19)
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- Visible light-induced intermolecular radical addition: Facile access to γ-ketoesters from alkyl-bromocarboxylates and enamines
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A highly efficient addition of alkyl α-bromocarboxylates to enamines by visible light-induced photoredox catalysis is reported. Compared with traditional methods, the reaction described here provided an alternative route for the construction of valuable γ-ketoesters in generally good yields.
- Hu, Bei,Chen, Haixia,Liu, Yan,Dong, Wuheng,Ren, Kai,Xie, Xiaomin,Xu, Hao,Zhang, Zhaoguo
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p. 13547 - 13550
(2015/01/09)
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- Iridium-catalyzed regiospecific and stereospecific allylic amination for the syntheses of α,β-unsaturated γ-amino esters and the bifurcation of the reaction pathway leading to the formation of oxazolidin-2-ones
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A pair of iridium-catalyzed regiospecific and stereospecific reactions of the carbonates of γ-hydroxy α,β-unsaturated esters were developed. The reaction pathways are strongly affected by the choice of amines employed. A diverse range of γ-substituted α,β-unsaturated γ-amino esters were prepared in excellent yields with various amine nucleophiles such as benzylamine, diallylamine, morpholine, aniline and N-methylaniline. Substitution at the γ-position was well tolerated, encompassing alkyl, aryl and heteroaryl substituents. Enantioenriched (E)-α,β-unsaturated γ-amino esters could also be synthesized from the corresponding enantioenriched allylic carbonates with complete chirality transfer. In sharp contrast, a series of 3,4-disubstituted oxazolidin-2-ones were obtained by using allylamine as a nucleophile.
- Lee, Jun Hee,Lee, Sang-Gi
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p. 2922 - 2927
(2013/07/19)
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- Aromatic-amide-derived olefins as a springboard: Isomerization-initiated palladium-catalyzed hydrogenation of olefins and reductive decarbonylation of acyl chlorides with hydrosilane
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A highly efficient catalytic protocol for the isomerization of substituted amide-derived olefins is presented that successfully uses a hydride palladium catalyst system generated from [PdCl2(PPh3)2] and HSi(OEt)3. The Z to E isomerization was carried out smoothly and resulted in geometrically pure substituted olefins. Apart from the cis-trans isomerization of double bonds, the selective reduction of terminal olefins and activated alkenes was performed with excellent functional group tolerance in the presence of an amide-derived olefin ligand, and the products were obtained in high isolated yields (up to >99 %). Furthermore, the palladium/hydrosilane system was able to promote the reductive decarbonylation of benzoyl chloride when a (Z)-olefin with an aromatic amide moiety was used as a ligand. Copyright
- Bai, Xing-Feng,Xu, Li-Wen,Zheng, Long-Sheng,Jiang, Jian-Xiong,Lai, Guo-Qiao,Shang, Jun-Yan
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supporting information; experimental part
p. 8174 - 8179
(2012/08/27)
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- STABILIZED ORGANOMETALLIC REAGENTS
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Compositions of stabilized forms of organometallic reagents, methods of preparing the stabilized forms, and methods of using the stabilized forms, are provided. Stabilized organometallic reagent compositions of the invention are sorbent solids permeated by the organometallic reagent. The reagent can be a Grignard reagent, a Reformatsky reagent, a zinc reagent of the type RZnX, R2Zn, Ar2Zn, R3ZnM, Ar3ZnM, and the like, an organolithium reagent such as n-butyllithium, a organocopper reagent, or other reactive, potentially pyrophoric reagent. The compositions are solids that can be weighed and dispensed in ambient air without requiring inert gas blanketing. The compositions can be prepared by contacting the sorbent solid, which can be silica, an alkyl silica, alumina, or other non-reactive sorbent solid with a solution of the organometallic reagent in a non-reactive solvent, then, removing the solvent, such as under vacuum. The stabilized composition can be used by extracting the organometallic reagent from the composition with a non-reactive solvent and contacting the solution with a reactant.
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Page/Page column 14
(2011/10/10)
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- Radical alkylations of alkyl halides and unactivated C-H bonds using vinyl triflates
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Radical alkylations of activated alkyl iodides and bromides were achieved using vinyl triflates in the presence of hexadimethyltin, whereas those of unactivated C-H bonds using vinyl triflates proceeded cleanly under tin-free conditions. Georg Thieme Verl
- Lee, Jin Young,Lim, Kyoung-Chan,Meng, Xiangjian,Kim, Sunggak
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experimental part
p. 1647 - 1650
(2010/09/04)
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- Chemoenzymatic and yeast-catalysed synthesis of diastereomeric ethyl γ-phenyl and γ-(n-pyridyl)paraconates
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The synthesis of γ-phenyl and γ-(n-pyridyl)paraconates was accomplished by chemical reduction of their respective ketodiester precursors followed by cyclisation of the resulting hydroxy diester intermediates. The cis- and trans-lactones thus obtained were separated and separately subjected to enzymatic hydrolysis with HLAP. The cis-lactonic esters had enantiomeric excesses ranging from 94% to 99%, while for the trans-isomers the ee's ranged from 80% to 93%. The same ketodiester precursors were subjected to reduction with a series of yeasts. The absolute configuration of trans-(-)-2-pyridyl paraconic acid was assigned by means of X-ray analysis of its hydrobromide salt, while the absolute configurations of the other lactones were determined via analysis of their respective CD curves.
- Forzato, Cristina,Furlan, Giada,Nitti, Patrizia,Pitacco, Giuliana,Valentin, Ennio,Zangrando, Ennio,Buzzini, Pietro,Goretti, Marta,Turchetti, Benedetta
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p. 2026 - 2036
(2008/12/23)
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- Intermolecular addition reaction to alkenes of acylmolybdenum complexes generated by oxidative addition of aryl or alkenyl halides with molybdenum(0) carbonyl complexes
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Acylmolybdenum species, generated by oxidative addition of aryl or alkenyl halides with molybdenum(0) carbonyl complex followed by carbon monoxide insertion, added to various kinds of alkenes intermolecularly to give simple addition products in good yields without formation of carbonylative Heck-type products. Georg Thieme Verlag Stuttgart.
- Sangu, Kenichiro,Watanabe, Toru,Takaya, Jun,Iwasawa, Nobuharu
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p. 929 - 933
(2008/02/02)
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- Thiazolium-catalyzed additions of acylsilanes: A general strategy for acyl anion addition reactions
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A strategy utilizing N-heterocyclic carbenes (NHCs) derived from thiazolium salts has been developed for the generation of carbonyl anions from acylsilanes. Synthetically useful 1,4-diketones and N-phosphinoyl-α- aminoketones have been prepared in good to excellent yields via NHC-catalyzed additions of acylsilanes to the corresponding α,β-unsaturated systems and N-phosphinoylimines. These organocatalytic reactions are air- and water-tolerant methods to execute robust carbonyl anion addition reactions. Additionally, polysubstituted aromatic furans and pyrroles have been efficiently synthesized in a one-pot process using this carbonyl anion methodology. The addition of alcohols to the reaction renders the process catalytic in thiazolium salt. In an effort to synthesize a potential intermediate along the proposed reaction pathway, silylated thiazolium carbinols have been identified to provide good yields of carbonyl anion addition products when subjected to the standard reaction conditions in the presence of suitable electrophiles.
- Mattson, Anita E.,Bharadwaj, Ashwin R.,Zuhl, Andrea M.,Scheidt, Karl A.
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p. 5715 - 5724
(2007/10/03)
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- One-pot synthesis of oxo acid derivatives by RhI-catalyzed chelation-assisted hydroacylation
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Various oxo acid derivatives were obtained directly from the reaction of aliphatic and aromatic aldehydes with ω-alkenoic acid derivatives in the presence of rhodium(I) complexes and 2-amino-3-picoline. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Jo, Eun-Ae,Jun, Chul-Ho
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p. 2504 - 2507
(2007/10/03)
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- Tin-free radical alkylation of ketones via N-silyloxy enamines
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The radical alkylation of ketones is achieved by their conversion into corresponding N-silyloxy enamines, followed by a radical reaction with alkyl halides bearing electron-withdrawing groups. The Royal Society of Chemistry 2006.
- Song, Hyun-Ji,Lim, Che Jo,Lee, Sunggi,Kim, Sunggak
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p. 2893 - 2895
(2008/09/18)
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- Radical alkylation of bis(silyloxy)enamine derivatives of organic nitro compounds
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(Chemical Equation Presented) Alkylation β to a nitro group by radical chemistry is made possible by initial conversion of the organic nitro compound into a bis(silyloxy)enamine (see scheme; TBSOTf=tert-butyldimethylsilyl trifluoromethanesulfonate). An advantage of the method is the simultaneous conversion of the nitro group into a synthetically useful oxime ether group.
- Jin, Young Lee,Hong, Young-Taek,Kim, Sunggak
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p. 6182 - 6186
(2007/10/03)
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- Synthesis of chiral 5-aryltetrahydrofuran-2-ones via yeast bioreduction of γ-keto acids and their esters
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Enantioselective reduction of γ-keto acids and related γ-keto esters with Saccharomyces cerevisiae (baker's yeast) leads to the formation of the corresponding chiral 5-aryltetrahydrofuran-2-ones in satisfactory chemical and optical yields. Pleiades Publishing, Inc., 2006.
- Mahmoodi,Yousefi-Malekroudi
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p. 365 - 368
(2007/10/03)
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- Efficient synthesis of γ-keto esters from enamines and EDA
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The reaction of enamines with ethyl diazoacetate (EDA) catalyzed by dirhodium and copper complexes provided γ-keto esters in good yields. The influences of catalyst, reaction solvent, temperature, and structure of enamines on this transformation were inve
- Huang, Dan,Yan, Ming,Zhao, Wei-Jie,Shen, Qi
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p. 745 - 750
(2007/10/03)
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- Fragmentation of tertiary cyclopropanol compounds catalyzed by vanadyl acetylacetonate
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Tertiary cyclopropanol compounds react with a catalytic amount of vanadyl acetylacetonate in the presence of oxygen affording β-hydroxyketones and β-diketones. For 3-substituted-bicyclo[4.1.0]alkanols, peroxides are obtained, as are the β-hydroxyketones. Conversely, 2- ethoxycarbonylcyclopropyl silyl ethers produce ethyl γ-oxocarboxylate derivatives given the same reaction conditions.
- Kirihara, Masayuki,Kakuda, Hiroko,Ichinose, Motohiro,Ochiai, Yuta,Takizawa, Shinobu,Mokuya, Asuka,Okubo, Kumiko,Hatano, Akihiko,Shiro, Motoo
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p. 4831 - 4839
(2007/10/03)
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- The Thiazolium-Catalyzed Sila-Stetter Reaction: Conjugate Addition of Acylsilanes to Unsaturated Esters and Ketones
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A new acyl anion addition reaction between acylsilanes and α,β-unsaturated conjugate acceptors promoted by a nucleophilic organic catalyst has been disclosed. The 1,4-dicarbonyl products produced in this reaction are highly useful synthons. Neutral carbenes (or zwitterions) generated in situ from commercial thiazolium salts are used as effective catalysts for the reaction which is in contrast to established anionic catalysts typically employed to promote the required Brook rearrangement (1,2-silyl shift from carbon to oxygen) involved in the reported reaction. This process successfully utilizes acylsilanes as tunable acyl anion progenitors and is tolerant of a wide range of structural diversity on the acylsilane or the conjugate acceptor. Copyright
- Mattson, Anita E.,Bharadwaj, Ashwin R.,Scheidt, Karl A.
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p. 2314 - 2315
(2007/10/03)
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