- 1,3-Difunctionalization of β-alkyl nitroalkenes via combination of Lewis base catalysis and radical oxidation
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Upon treatment with a Lewis base catalyst, β-alkyl-substituted nitroalkenes could be readily converted into allylic nitro compounds. Examples of either C-1 or C-3 functionalization methods have been reported through nitro-elimination, giving alkene products. In this work, successful 1,3-difunctionalization was achieved through a synergetic Lewis base catalysis and TBHP radical oxidation, giving vinylic alkoxyamines in good to excellent yields. This work further extended the general synthetic application of β-alkyl nitroalkenes.
- Wang, Ye,Zheng, Lei,Shi, Xiaodong,Chen, Yunfeng
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supporting information
p. 886 - 889
(2021/02/01)
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- Palladium-Catalyzed Markovnikov Hydroaminocarbonylation of 1,1-Disubstituted and 1,1,2-Trisubstituted Alkenes for Formation of Amides with Quaternary Carbon
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Hydroaminocarbonylation of alkenes is one of the most promising yet challenging methods for the synthesis of amides. Herein, we reported the development of a novel and effective Pd-catalyzed Markovnikov hydroaminocarbonylation of 1,1-disubstituted or 1,1,2-trisubstituted alkenes with aniline hydrochloride salts to afford amides bearing an α quaternary carbon. The reaction makes use of readily available starting materials, tolerates a wide range of functional groups, and provides a facile and straightforward approach to a diverse array of amides bearing an α quaternary carbon. Mechanistic investigations suggested that the reaction proceeded through a palladium hydride pathway. The hydropalladation and CO insertion are reversible, and the aminolysis is probably the rate-limiting step.
- Yang, Hui-Yi,Yao, Ya-Hong,Chen, Ming,Ren, Zhi-Hui,Guan, Zheng-Hui
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supporting information
p. 7298 - 7305
(2021/05/26)
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- Visible-light-promoted radical alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester: Synthesis of oxazolines
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An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.
- Ding, Hao,Huang, Panyi,Jin, Can,Su, Weike,Sun, Bin,Yan, Zhiyang,Zhao, Haiyun
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supporting information
(2021/10/29)
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- MnBr2 catalyzed regiospecific oxidative Mizoroki-Heck type reaction
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Herein, we report an unprecedented regiospecific oxidative Mizoroki-Heck type reaction for the synthesis of ɑ-difluoromethyl homoallylic alcohols. The reaction shows broad substrate scopes and high functional group tolerance. Late-stage functionalization of complex biologically active molecules demonstrates the synthetic potential of this transformation. Mechanistic study supports the involvement of MnBr2 catalyzed radical 1,2-silyl transfer.
- Chen, Xiang,Chen, Yi-Hung,Liu, Shanshan,Shen, Xiao,Zhu, Zhihong
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supporting information
(2021/11/27)
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- Construction of Various Bridged Polycyclic Skeletons by Palladium-Catalyzed Dearomatization
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A powerful palladium-catalyzed dearomative cyclization was developed that provides facile access to eight types of bridged tetracyclic skeletons bearing various ring sizes and heterocycles. With this method, several skeletons or analogues of natural products, including tubingensin B and dracaenones, were synthesized. Asymmetric dearomative cyclization enables the construction of various enantiomerically enriched bridged polycyclic systems with up to 99 % ee by employing a chiral palladium catalyst.
- Mu, Xingye,Peng, Henian,Tang, Wenjun,Wu, Ting,Xiong, Wenrui,Yu, Hanxiao
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supporting information
p. 8143 - 8147
(2020/03/24)
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- Aqueous ZnCl2 Complex Catalyzed Prins Reaction of Silyl Glyoxylates: Access to Functionalized Tertiary α-Silyl Alcohols
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An efficient Prins reaction of silyl glyoxylates in the presence of an aqueous ZnCl2 complex as a catalyst was developed, providing functionalized tertiary α-silyl alcohols in high yields under mild conditions. A preliminary investigation indicated that the aqueous ZnCl2 complex acted as a dual functional catalyst of Br?nsted and Lewis acid to activate the carbonyl groups of silyl glyoxylates via a dual-activation model.
- Han, Man-Yi,Pan, Hong,Li, Pinhua,Wang, Lei
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p. 5825 - 5837
(2020/05/22)
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- An Aliphatic Bischler-Napieralski Reaction: Dihydropyridones by Cyclocarbonylation of 3-Allylimidazolidin-4-ones
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The N-chloroformylimidazolidinone derivative of enantiopure l-alanine was deprotonated to form an enolate and functionalized with a series of allylic halides. Treatment of the resulting carbamoyl chlorides with potassium iodide led to cyclization of the allylic substituent onto the carbonyl group in an intramolecular aliphatic Friedel-Crafts-type acylation that corresponds to an aliphatic Bischler-Napieralski reaction. The product 3,4-dihydropyridinones were amenable to further functionalization, and finally hydrolysis, to deliver a series of enantio-enriched pipecolic acid derivatives.
- Amer, Mostafa M.,Olaizola, Olatz,Carter, Jennifer,Abas, Hossay,Clayden, Jonathan
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supporting information
p. 253 - 256
(2020/01/02)
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- Synthesis of Tertiary Benzylic Nitriles via Nickel-Catalyzed Markovnikov Hydrocyanation of α-Substituted Styrenes
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The Markovnikov hydrocyanation of α-substituted styrenes enables the synthesis of tertiary benzylic nitriles under nickel catalysis. The Lewis-acid-free transformation features an unprecedented functional groups tolerance, including the-OH and-NH2 groups. A broad range of tertiary benzylic nitriles were obtained in good to excellent yields. In addition, an asymmetric version of this reaction was preliminarily investigated.
- Xing, Yidan,Yu, Rongrong,Fang, Xianjie
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supporting information
p. 1008 - 1012
(2020/02/04)
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- Palladium/Acid Relay Catalyzed Tandem Heck Coupling/6-Endo Cyclization between ortho-Halogenated Benzoates and Unactivated Terminal Alkenes for the Synthesis of 1-Isochromanones
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We report a unique and expeditious route to synthesize 1-isochromanone derivatives through palladium catalyzed tandem Heck coupling/6-endo hydroacyloxylation cyclization between readily available ortho-halogenated benzoates and unactivated alkenes. Various 2-bromo or 2-iodo benzoates can be coupled efficiently with a broad range of alkenes to afford functionalized 1-isochromanones in high yields. Significantly, this cost-efficient and easy-to-handle synthetic methodology will have great prospect application in the synthetic and medicinal chemistry. (Figure presented.).
- Wen, Zhen-Kang,Ge, Xiao-Min,Zhao, Ze-Kai,Chao, Jian-Bin
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supporting information
p. 983 - 988
(2019/01/30)
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- Oxidative [4+2] Cycloaddition of α-(N-Arylamino) Carbonyls with Aryl Alkenes by Multiple C-H Functionalizations and [1,2]-Aryl Shifts
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A new, general copper-catalyzed oxidative tandem [4+2] cycloaddition of α-(N-arylamino) carbonyl compounds with aryl alkenes to produce highly substituted quinolines has been developed, which allows the formation of three new C-C bonds through a sequence of multiple C-H functionalizations, annulation, and [1,2]-aryl shifts.
- Wei, Wen-Ting,Teng, Fan,Li, Yang,Song, Ren-Jie,Li, Jin-Heng
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supporting information
p. 6285 - 6288
(2019/09/06)
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- Highly Enantioselective Iridium-Catalyzed Hydrogenation of 2-Aryl Allyl Phthalimides
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The iridium-catalyzed asymmetric hydrogenation of 2-aryl allyl phthalimides to afford enantioenriched β-aryl-β-methyl amines is presented. Recently developed Ir-MaxPHOX catalysts are used for this enantioselective transformation. The mild reaction conditions and the feasible removal of the phthalimido group makes this catalytic method easily scalable and of great interest to afford chiral amines. The importance of this new methodology is exemplified by the formal synthesis of (R)-Lorcaserin, OTS514, and enantiomerically enriched 3-methyl indolines.
- Cabré, Albert,Romagnoli, Elia,Martínez-Balart, Pol,Verdaguer, Xavier,Riera, Antoni
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supporting information
p. 9709 - 9713
(2019/11/19)
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- Copper-Catalyzed Enantio- and Diastereoselective Addition of Silicon Nucleophiles to 3,3-Disubstituted Cyclopropenes
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A highly stereocontrolled syn-addition of silicon nucleophiles across cyclopropenes with two different geminal substituents at C3 is reported. Diastereomeric ratios are excellent throughout (d.r.≥98:2) and enantiomeric excesses usually higher than 90 %, even reaching 99 %. This copper-catalyzed C?Si bond formation closes the gap of the direct synthesis of α-chiral cyclopropylsilanes.
- Zhang, Liangliang,Oestreich, Martin
-
supporting information
p. 14304 - 14307
(2019/11/13)
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- Regioselective Diboron-Mediated Semireduction of Terminal Allenes
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A method for the regioselective reduction of the terminal double bond of 1,1-disubstituted allenes has been developed. In the presence of a palladium catalyst, tetrahydroxydiboron and stoichiometric water, allene semireduction proceeds in high yield to afford Z-alkenes selectively.
- Gates, Ashley M.,Santos, Webster L.
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supporting information
p. 4619 - 4624
(2019/12/11)
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- A Copper Catalyst with a Cinchona-Alkaloid-Based Sulfonamide Ligand for Asymmetric Radical Oxytrifluoromethylation of Alkenyl Oximes
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A copper-catalyzed asymmetric radical oxytrifluoromethylation of alkenyl oxime and Togni's reagent has been successfully developed, thereby providing straightforward access to CF3-containing isoxazolines bearing α-tertiary stereocenters with excellent yield and enantioselectivity. The key to success is the rational design of cinchona-alkaloid-based sulfonamides as neutral/anionic hybrid ligands to effectively control the stereochemistry in copper-catalyzed reactions involving free alkyl radical species. The utility of this method is illustrated by efficient transformation of the products into useful chiral CF3-containing 1,3-aminoalcohols.
- Li, Xi-Tao,Gu, Qiang-Shuai,Dong, Xiao-Yang,Meng, Xiang,Liu, Xin-Yuan
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supporting information
p. 7668 - 7672
(2018/05/30)
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- Copper-catalyzed radical oxytrifluoromethylation of alkenyl oximes at ambient temperature
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A mild and efficient copper-catalyzed radical oxytrifluoromethylation reaction of alkenyl oximes was successfully developed. The method provides a straightforward access to a wide range of CF3-containing isoxazolines in good to excellent yields.
- Li, Xi-Tao,Lv, Ling,Gu, Qiang-Shuai,Liu, Xin-Yuan
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supporting information
p. 6041 - 6046
(2018/09/11)
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- Iodine-Catalyzed Facile Approach to Sulfones Employing TosMIC as a Sulfonylating Agent
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A novel iodine-catalyzed functionalization of a variety of olefins and alkynes and direct decarboxylative functionalization of cinnamic and propiolic acids with TosMIC to provide access to various vinyl, allyl, and β-iodo vinylsulfones is described. This simple, efficient, and environmentally benign approach employing inexpensive molecular iodine as a catalyst demonstrates a versatile protocol for the synthesis of highly valuable sulfones, rendering it attractive to both synthetic and medicinal chemistry.
- Kadari, Lingaswamy,Palakodety, Radha Krishna,Yallapragada, Lakshmi Prapurna
-
supporting information
p. 2580 - 2583
(2017/05/24)
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- Water-Enabled Catalytic Asymmetric Michael Reactions of Unreactive Nitroalkenes: One-Pot Synthesis of Chiral GABA-Analogs with All-Carbon Quaternary Stereogenic Centers
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Water enables new catalytic reactions for otherwise unreactive substrate systems. Under the “on water” reaction conditions, extremely unreactive β,β-disubstituted nitroalkenes smoothly underwent enantioselective Michael addition reactions with dithiomalonates using a chiral squaramide catalyst, affording both enantiomers of highly enantioenriched Michael adducts with all-carbon-substituted quaternary centers. The developed “on water” protocol was successfully applied for the scalable one-pot syntheses of chiral GABA analogs with all-carbon quaternary stereogenic centers at the β-position, which might show highly interesting pharmaceutical properties.
- Sim, Jae Hun,Song, Choong Eui
-
supporting information
p. 1835 - 1839
(2017/02/05)
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- Chelation versus Non-Chelation Control in the Stereoselective Alkenyl sp2 C?H Bond Functionalization Reaction
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A hydroxy group chelation-assisted stereospecific oxidative cross-coupling reaction between alkenes was developed under mild reaction conditions. In the presence of palladium catalyst, the alkenes tethered with hydroxy functionality can couple efficiently with electron-deficient alkenes to form the corresponding multi-substituted olefin products. The hydroxy group on the substrate could play dual roles in reaction, acting as the directing group for alkenyl C?H bond activation and controlling the stereoselectivity of the products.
- Liang, Qiu-Ju,Yang, Chao,Meng, Fei-Fan,Jiang, Bing,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 5091 - 5095
(2017/04/24)
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- Asymmetric Nitrone Synthesis via Ligand-Enabled Copper-Catalyzed Cope-Type Hydroamination of Cyclopropene with Oxime
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We report realization of the first enantioselective Cope-type hydroamination of oximes for asymmetric nitrone synthesis. The ligand promoted asymmetric cyclopropene "hydronitronylation" process employs a Cu-based catalytic system and readily available starting materials, operates under mild conditions and displays broad scope and exceptionally high enantio- and diastereocontrol. Preliminary mechanistic studies corroborate a CuI-catalytic profile featuring an olefin metalla-retro-Cope aminocupration process as the key C-N bond forming event. This conceptually novel reactivity enables the first example of highly enantioselective catalytic nitrone formation process and will likely spur further developments that may significantly expedite chiral nitrone synthesis.
- Li, Zhanyu,Zhao, Jinbo,Sun, Baozhen,Zhou, Tingting,Liu, Mingzhu,Liu, Shuang,Zhang, Mengru,Zhang, Qian
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supporting information
p. 11702 - 11705
(2017/09/07)
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- Substrate Scope Evaluation of the Enantioselective Reduction of β-Alkyl-β-arylnitroalkenes by Old Yellow Enzymes 1-3 for Organic Synthesis Applications
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The substrate scope of the old yellow enzyme catalyzed reduction of β-alkyl-β-arylnitroalkenes is investigated. Compounds bearing either alkyl chains of increasing length at the carbon atom in position β to the nitro group or different substituents on the aromatic ring are prepared and submitted to bioreduction, to define the synthetic potential of this enantioselective reaction in the preparation of chiral fine chemicals. The versatility of the resulting nitroalkanes as chiral building blocks is shown by reducing the nitro group into a primary amine and by converting it into a carboxylic acid moiety by Meyer reaction. An "explosion" of chiral products can be observed by combining the highly enantioselective ene-reductase-mediated reduction of nitroalkenes with the chemical versatility of the nitro group.
- Bertolotti, Mattia,Brenna, Elisabetta,Crotti, Michele,Gatti, Francesco G.,Monti, Daniela,Parmeggiani, Fabio,Santangelo, Sara
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p. 577 - 583
(2016/02/23)
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- Synthesis of 2,5-Diaryl-1,5-dienes from Allylic Bromides Using Visible-Light Photoredox Catalysis
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Visible-light photoreductive coupling of 2-arylallyl bromides in the presence of the photocatalyst Ru(bpy)3(PF6)2, a Hantzsch ester, and i-Pr2NEt gives 2,5-diaryl-1,5-dienes in high yield. This method avoids the use of stoichiometric metal reductants and is compatible with the presence of halogen, alkyl, electron-donating, and electron-withdrawing substituents on the aromatic ring.
- Pratsch, Gerald,Overman, Larry E.
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p. 11388 - 11397
(2015/12/01)
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- Iridium-Catalyzed Enantioselective Hydrogenation of β,β-Disubstituted Nitroalkenes
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A highly efficient, iridium-catalyzed, enantioselective hydrogenation of β,β-disubstituted nitroalkenes has been developed. Using a complex consisting of iridium and (S,S)-f-spiroPhos as the catalyst, a variety of β,β-disubstituted nitroalkenes were successfully hydrogenated to the corresponding chiral nitroalkanes with excellent enantioselectivities (up to 98% ee) and high turnover numbers (TON=1000).
- Liu, Man,Kong, Duanyang,Li, Meina,Zi, Guofu,Hou, Guohua
-
supporting information
p. 3875 - 3879
(2016/01/25)
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- Highly enantioselective hydrogenation of β,β-disubstituted nitroalkenes
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Building the building blocks: A highly enantioselective hydrogenation of ?-aryl-?-alkyl disubstituted nitroalkenes 1 has been developed. This method results in enantiomerically pure nitroalkanes 2, which are versatile precursors for chemical synthesis.
- Li, Shengkun,Huang, Kexuan,Cao, Bonan,Zhang, Jiwen,Wu, Wenjun,Zhang, Xumu
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supporting information; experimental part
p. 8573 - 8576
(2012/09/10)
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- Mechanistic switch via subtle ligand modulation: Palladium-catalyzed synthesis of α,β-substituted styrenes via C-H bond functionalization
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A new catalyst system able to efficiently perform the synthesis of styrenes via C-H bond functionalization and a subtle ligand modification are described. The high level of activity achieved allows for the synthesis of highly functionalized α,β-substituted styrenes, even the elusive E-configured trisubstituted olefins, in a regio- and stereoselective manner. Mechanistic experiments allowed for the identification of the corresponding synthetic intermediates.
- Flores-Gaspar, Areli,Martin, Ruben
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supporting information; experimental part
p. 1223 - 1228
(2011/06/26)
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- Highly enantioselective reduction of β,β-disubstituted aromatic nitroalkenes catalyzed by Clostridium sporogenes
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(Chemical Equation Presented) This is the first report of the use of Clostridium sporogenes extracts for enantioselective reduction of C=C double bonds of β,β-disubstituted (1) and α,β-disubstituted nitroalkenes (3). Crude enzyme preparations reduced aryl derivatives 1a-e and 1h, in 35-86% yield with ≥97% ee. Reduction of (E)- and (Z)-isomers of 1c gave the same enantiomer of 2c (≥99% ee). In contrast, α,β- disubstituted nitroalkene 3a was a poor substrate, yielding (S)-4a in low yield (10-20%), and the ee (30-70% ee) depended on NADH concentration. An efficient synthesis of a library of nitroalkenes 1 is described.
- Fryszkowska, Anna,Fisher, Karl,Gardiner, John M.,Stephens, Gill M.
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p. 4295 - 4298
(2008/12/20)
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- Copper-carbene complexes as catalysts in the synthesis of functionalized styrenes and aliphatic alkenes
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(NHC)-Cu (NHC = N-heterocyclic carbene) complexes efficiently catalyzed the methylenation of a variety of aliphatic and aromatic aldehydes and ketones in the presence of trimethylsilyldiazomethane, triphenylphosphine, and 2-propanol. The copper catalysts are not only inexpensive compared to rhodium complexes, but they also exhibit better functional group compatibility with aromatic aldehydes and ketones. Indeed very high yields were obtained for the formation of styrenes containing nitro, trifluoromethyl, amino, and ester groups, as well as for pyridine-, pyrrole-, and indole-substituted alkenes.
- Lebel, Helene,Davi, Michael,Diez-Gonzalez, Silvia,Nolan, Steven P.
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p. 144 - 149
(2007/10/03)
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- Cobalt-catalyzed vinylation of functionalized aryl halides with vinyl acetates
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A new method for the preparation of styrene derivatives is described on the basis of the activation of aryl halides by low-valent cobalt species. A combination of CoII bromide and 2,2′-bipyridine is suitable as catalyst for the cross-coupling reaction of a wide range of aromatic halides (X = Cl, Br, I), mostly bearing sensitive moieties, with vinyl acetates. These reactions proceed under mild conditions in the presence of the appropriate reducing agent to afford α-substituted styrene compounds in satisfactory to high yields. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Amatore, Muriel,Gosmini, Corinne,Perichon, Jacques
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p. 989 - 992
(2007/10/03)
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- Indium(III) bromide-catalyzed chemioselective dimerization of vinylarenes
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Indium(III) bromide catalyzes the dimerization of α-substituted vinylarenes. Chemioselectivity towards open chain or cyclic dimers depends on the nature of the substituent at the aryl group of the vinylarene.
- Peppe, Clovis,Lang, Ernesto Schulz,De Andrade, Fabiano Molinos,De Castro, Liérson Borges
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p. 1723 - 1726
(2007/10/03)
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- Characterization of a series of 3-amino-2-phenylpropene derivatives as novel bovine chromaffin vesicular monoamine transporter inhibitors
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A series of 3-amino-2-phenylpropene (APP) derivatives have been synthesized and characterized as novel competitive inhibitors, with Ki values in the μM range, for the bovine chromaffin granule membrane monoamine transporter(s) (bVMAT). Although, these inhibitors are structurally similar to the bVMAT substrate tyramine, none of them were measurably transported into the granule. Structure - activity studies have revealed that, while the 3′- or 4′-OH groups on the aromatic ring enhance the inhibition potency, Me or OMe groups in these positions reduce the inhibition potency. Halogen substitution on the 4′-position of the aromatic ring causes gradual increase of the inhibition potency parallel to the electron donor ability of the halogen. Substituents on the NH2 as well as on the 3-position of the alkyl chain reduce the inhibition potency. Comparative structure - activity analyses of APP derivatives with tyramine and the neurotoxin 1-methyl-4-phenylpyridinium suggest that the flexibility of the side chain and the relative orientation of the NH2 group may be critical for the efficient transport of the substrate through the bVMAT. Comparable bVMAT affinities of these inhibitors to that of DA and other pharmacologically active amines suggest that they are suitable for the structure activity and mechanistic studies of monoamine transporters and may also be useful in modeling the mechanism of action of amphetamine-related derivatives.
- Perera, Rohan P.,Wimalasena, D. Shyamali,Wimalasena, Kandatege
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p. 2599 - 2605
(2007/10/03)
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- Palladium-catalyzed coupling reaction of alkenylgalliums with aryl halides
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Treatment of aryl halides with alkenylgallium dichloride, prepared from GaCl3 and alkenylmagnesium bromide, in the presence of a catalytic amount of palladium provided cross-coupling products in good yields.
- Mikami, Satoshi,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1137 - 1139
(2007/10/03)
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- A NOVEL APPROACH TO THE 5a-ARYLDECAHYDRO-2-BENZAZEPINE SKELETON
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Trienes (3) are prepared and their intramolecular cyclisation to give the 5a-aryloctahydrobenzazepines (6) is described.
- Handa, Sheetal,Jones, Keith,Newton, Christopher G.
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p. 3841 - 3844
(2007/10/02)
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