- 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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- 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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- 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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- Synthesis of Deuterium-Labeled 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) and Quantitative Determination of TDN and Isomeric Vitispiranes in Riesling Wines by a Stable-Isotope-Dilution Assay
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The C13-norisoprenoid aroma compounds 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) and isomeric 2,10,10-trimethyl-6-methylene-1-oxaspiro[4.5]dec-7-enes, so-called vitispiranes, are considered to be biosynthetically related. They occur at higher concentrations in bottle-aged Riesling wines especially and are important contributors to the varietal aroma of Riesling wines. Because of the variation of the quantitative methods and data reported in the literature, a redetermination of concentration levels for both free and total TDN and isomeric vitispiranes, especially in German Riesling wines, was performed using a stable-isotope-dilution assay (SIDA). For this purpose, a novel six-step synthetic route to TDN and deuterium-labeled TDN was developed. A standardized sample preparation for TDN and vitispiranes and a rapid acid-hydrolysis method at genuine wine-pH conditions for the conversion of the precursors into TDN and vitispiranes were also developed. Automated HS-SPME was applied to 250 wine samples from two wine competitions, and analysis was performed by gas chromatography-mass spectrometry with selected-ion monitoring (GC-SIM-MS) as well as selected-reaction monitoring (GC-SRM-MS).
- G?k, Recep,Bechtloff, Pia,Ziegler, Michael,Schmarr, Hans-Georg,Fischer, Ulrich,Winterhalter, Peter
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p. 6414 - 6422
(2019/06/07)
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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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- Combined Photoredox/Enzymatic C?H Benzylic Hydroxylations
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Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value-added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single-flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.
- Betori, Rick C.,May, Catherine M.,Scheidt, Karl A.
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supporting information
p. 16490 - 16494
(2019/11/03)
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- Discovery of Oxime Ethers as Hepatitis B Virus (HBV) Inhibitors by Docking, Screening and In Vitro Investigation
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A series of oxime ethers with C6-C4 fragment was designed and virtually bioactively screened by docking with a target, then provided by a Friedel-Crafts reaction, esterification (or amidation), and oximation from p-substituted phenyl derivatives (Methylbenzene, Methoxybenzene, Chlorobenzene). Anti-hepatitis B virus (HBV) activities of all synthesized compounds were evaluated with HepG2.2.15 cells in vitro. Results showed that most of compounds exhibited low cytotoxicity on HepG2.2.15 cells and significant inhibition on the secretion of HBsAg and HBeAg. Among them, compound 5c-1 showed the most potent activity on inhibiting HBsAg secretion (IC50 = 39.93 μM, SI = 28.51). Results of the bioactive screening showed that stronger the compounds bound to target human leukocyte antigen A protein in docking, the more active they were in anti-HBV activities in vitro.
- Tan, Jie,Zhou, Min,Cui, Xinhua,Wei, Zhuocai,Wei, Wanxing
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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 0118; 0119; 0120
(2018/07/30)
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- Light-Driven Vitamin B12-Catalysed Generation of Acyl Radicals from 2-S-Pyridyl Thioesters
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Acyl radicals are invaluable intermediates in organic synthesis, however their generation remains challenging. Herein, we present an unprecedented light-driven, cobalt-catalysed method for the generation of acyl radicals from readily available 2-S-pyridyl thioesters. The synthetic potential of this methodology was demonstrated in the Giese-type acylation of activated olefins in the presence of heptamethyl cobyrrinate. This vitamin B12 derivative proved to be the most efficient catalyst in the studied process. The developed method features broad substrate scope (38 examples), good functional group tolerance, and mild reaction conditions. Moreover, it is easily scalable (illustrated on a 20-fold scale-up procedure), enabling its preparative use. Mechanistic studies revealed that the reaction proceeds via a radical pathway with the key steps involving the formation of an acyl-vitamin B12 complex and subsequent photolysis of the Co?C bond. (Figure presented.).
- Ociepa, Micha?,Baka, Oskar,Narodowiec, Jakub,Gryko, Dorota
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supporting information
p. 3560 - 3565
(2017/10/24)
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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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- 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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- 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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- Sequential rhodium-catalyzed stereo- and regioselective addition of organoboron derivatives to the alkyl 4-hydroxy-2-alkynoates/lactonizaction reaction
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(Chemical Equation Presented) The sequential rhodium-catalyzed addition/lactonization reaction of organoboron derivatives to alkyl 4-hydroxy-2-alkynoates would constitute a novel methodology for the synthesis of 4-aryl/heteroaryl/vinyl-2(5H)-furanones wit
- Alfonsi, Maria,Arcadi, Antonio,Chiarini, Marco,Marinelli, Fabio
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p. 9510 - 9517
(2008/03/17)
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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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- Preparation of β-substituted γ-keto esters by the grignard reaction on N-acylpyrazoles
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Various γ-keto esters were prepared by either the alcoholysis of N-(4-oxoalkanoyl)pyrazoles or the Grignard replacement of pyrazole moiety of 4-(N-pyrazolyl)-4-oxoalkanoic esters. By using 3-phenyl-ι-menthopyrazole as a chiral auxiliary, β-substituted γ-keto esters were enantioselectively obtained.
- Kashima, Choji,Shirahata, Yoshie,Tsukamoto, Yoshihiro
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p. 309 - 317
(2007/10/03)
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- ortho-halogeno substituents effect in asymmetric cyclization of 4-aryl-4-pentenals using a rhodium catalyst
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Asymmetric cyclization of 4-aryl-4-pentenals by using a cationic [Rh((R)-BINAP)]ClO4 afforded (3R)-3-substituted cyclopentanones; on the other hand, the cyclization of 4-pentenals bearing ortho-halogeno phenyl groups afforded the opposite (3S)-ones.
- Fujio, Masakazu,Tanaka, Masakazu,Wu, Xiao-Ming,Funakoshi, Kazuhisa,Sakai, Kiyoshi,Suemune, Hiroshi
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p. 881 - 882
(2007/10/03)
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- "Me3Al-TMSOSO2CF3" a new reagent for conversion of carbonyl to geminal dimethyl functionality: Regiospecific synthesis of alkylated a ring of arotinoids
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Regiospecific synthesis of alkylated A ring of arotinoids has been achieved by using Me3Al-TMSOSO2CF3 as a key reagent for conversion of carbonyl to a geminal dimethyl functionality.
- Kim, Choung Un,Misco, Peter F.,Luh, Bing Y.,Mansuri, Muzammil M.
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p. 3017 - 3020
(2007/10/02)
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- THE REACTION OF ALKYL 4-HYDROXY-2-ALKYNOATES AND 4-HYDROXY-2-ALKYN-1-ONES WITH PALLADIUM TRIBUTYLAMMONIUM FORMATE AND WITH TRIBUTYLAMINE: PREPARATION OF 1,4-DICARBONYL COMPOUNDS
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Ethyl 4-oxo-2-alkenoates and 1,4-dioxo-2-alkenes are easily prepared by treating ethyl 4-hydroxy-2-alkynoates and 4-hydroxy-2-alkyn-1-ones with n-tributylamine.Treatment of ethyl 4-hydroxy-2-alkynoates and 4-hydroxy-2-alkyn-1-ones with palladium-tributylammonium formate produces ethyl 4-oxo-alkanoates and 1,4-alkandiones in good to high yield through a novel one-pot isomerization/hydrogenation reaction.
- Arcadi, A.,Cacchi, S.,Marinelli, F.,Misiti, D.
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p. 1457 - 1460
(2007/10/02)
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