- An Amine-Assisted Ionic Monohydride Mechanism Enables Selective Alkyne cis-Semihydrogenation with Ethanol: From Elementary Steps to Catalysis
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The selective synthesis of Z-alkenes in alkyne semihydrogenation relies on the reactivity difference of the catalysts toward the starting materials and the products. Here we report Z-selective semihydrogenation of alkynes with ethanol via a coordination-induced ionic monohydride mechanism. The EtOH-coordination-driven Cl- dissociation in a pincer Ir(III) hydridochloride complex (NCP)IrHCl (1) forms a cationic monohydride, [(NCP)IrH(EtOH)]+Cl-, that reacts selectively with alkynes over the corresponding Z-alkenes, thereby overcoming competing thermodynamically dominant alkene Z-E isomerization and overreduction. The challenge for establishing a catalytic cycle, however, lies in the alcoholysis step; the reaction of the alkyne insertion product (NCP)IrCl(vinyl) with EtOH does occur, but very slowly. Surprisingly, the alcoholysis does not proceed via direct protonolysis of the Ir-C(vinyl) bond. Instead, mechanistic data are consistent with an anion-involved alcoholysis pathway involving ionization of (NCP)IrCl(vinyl) via EtOH-for-Cl substitution and reversible protonation of Cl- ion with an Ir(III)-bound EtOH, followed by β-H elimination of the ethoxy ligand and C(vinyl)-H reductive elimination. The use of an amine is key to the monohydride mechanism by promoting the alcoholysis. The 1-amine-EtOH catalytic system exhibits an unprecedented level of substrate scope, generality, and compatibility, as demonstrated by Z-selective reduction of all alkyne classes, including challenging enynes and complex polyfunctionalized molecules. Comparison with a cationic monohydride complex bearing a noncoordinating BArF- ion elucidates the beneficial role of the Cl- ion in controlling the stereoselectivity, and comparison between 1-amine-EtOH and 1-NaOtBu-EtOH underscores the fact that this base variable, albeit in catalytic amounts, leads to different mechanisms and consequently different stereoselectivity.
- Huang, Zhidao,Wang, Yulei,Leng, Xuebing,Huang, Zheng
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supporting information
p. 4824 - 4836
(2021/04/07)
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- Photoinduced copper-catalyzed dual decarboxylative coupling of α,β-unsaturated carboxylic acids with redox-active esters
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The first photoinduced copper-catalyzed dual decarboxylative cross-coupling of α,β-unsaturated carboxylic acids and redox-active esters has been developed. This reaction enabled C(sp2)–C(sp3) bond formation, which afforded a variety of synthetically valuable alkene derivatives. Many α,β-unsaturated carboxylic acids and redox-active ester derivatives were tolerant to this reaction. The reaction also tolerated many common functional groups.
- Lu, Xiao-Yu,Gao, Ang,Liu, Qi-Le,Xia, Ze-Jie
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supporting information
(2021/06/15)
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- Dinuclear cobalt complex-catalyzed stereodivergent semireduction of alkynes: Switchable selectivities controlled by H2O
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Catalytic semireduction of internal alkynes to alkenes is very important for organic synthesis. Although great success has been achieved in this area, switchable Z/E stereoselectivity based on a single catalyst for the semireduction of internal alkynes is a longstanding challenge due to the multichemo- and stereoselectivity, especially based on less-expensive earth-abundant metals. Herein, we describe a switchable semireduction of alkynes to (Z)- or (E)-alkenes catalyzed by a dinuclear cobalt complex supported by a macrocyclic bis pyridyl diimine (PDI) ligand. It was found that cis-reduction of the alkyne occurs first and the Z-E alkene stereoisomerization process is formally controlled by the amount of H2O, since the concentration of H2O may influence the catalytic activity of the catalyst for isomerization. Therefore, this protocol provides a facile way to switch to either the (Z)- or (E)-olefin isomer in a single transformation by adjusting the amount of water.
- Chen, Ke,Zhu, Hongdan,Li, Yuling,Peng, Qian,Guo, Yinlong,Wang, Xiaoming
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p. 13696 - 13705
(2021/11/16)
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- Copper porphyrin-catalyzed cross dehydrogenative coupling of alkanes with carboxylic acids: Esterification and decarboxylation dual pathway
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A dual-functional copper porphyrin-catalyzed cross dehydrogenative coupling (CDC) of carboxylic acids with alkanes was reported firstly. The reaction gives allylic esters or alkylalkenes depending on the carboxylic acid substrates. Copper porphyrin catalyzed CDC method has the superiority of short reaction time, good functional group tolerance, base and solvent free, producing target products in an atom-economic manner.
- Chen, Xiao-Yan,Yang, Shuang,Ren, Bao-Ping,Shi, Lei,Lin, Dong-Zi,Zhang, Hao,Liu, Hai-Yang
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- Visible-Light-Mediated C-I Difluoroallylation with an α-Aminoalkyl Radical as a Mediator
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Herein, we report a protocol for direct visible-light-mediated C-I difluoroallylation reactions of α-trifluoromethyl arylalkenes with alkyl iodides at room temperature with an α-aminoalkyl radical as a mediator. The protocol permits efficient functionalization of various α-trifluoromethyl arylalkenes with cyclic and acyclic primary, secondary, and tertiary alkyl iodides and is scalable to the gram level. This mild protocol uses an inexpensive mediator and is suitable for late-stage functionalization of complex natural products and drugs.
- Yue, Fuyang,Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin
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p. 7306 - 7310
(2021/10/01)
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- A Solid-Phase Assisted Flow Approach to In Situ Wittig-Type Olefination Coupling
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Described herein is the development of a continuous flow, solid-phase triphenylphosphine (PS-PPh3) assisted protocol to facilitate the in situ coupling of reciprocal pairs of halogen and carbonyl functionalised molecular pairs by a Wittig olefination within 15 mins. The protocol entails injecting a single solution (1 : 1 CHCl3 : EtOH) containing the halogenated and carbonyl-based substrates into a continuously flowing stream of CHCl3 : EtOH (1 : 1), passed through a fixed bed of K2CO3 and PS-PPh3. With advancement to the previous PS-PPh3 coupling procedures, the method employs a traditional polystyrene-based immobilisation matrix, the substrate scope of the protocol extended to substituted ketones, secondary alkyl chlorides, and an unprotected maleimide scaffold.
- Aldrich-Wright, Janice R.,Dankers, Christian,Gordon, Christopher P.,Polyzos, Anastasios,Tadros, Joseph
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supporting information
p. 4184 - 4194
(2021/08/24)
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- Visible-Light-Mediated Alkenylation of Alkyl Boronic Acids without an External Lewis Base as an Activator
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Herein we report a protocol for the direct visible-light-mediated alkenylation of alkyl boronic acids at room temperature without an external Lewis base as an activator, and we propose a mechanism involving benzenesulfinate activation of the alkyl boronic acids. The protocol permits the efficient functionalization of a broad range of cyclic and acyclic primary and secondary alkyl boronic acids with various alkenyl sulfones. We demonstrated its utility by preparing or functionalizing several pharmaceuticals and natural products.
- Yue, Fuyang,Dong, Jianyang,Liu, Yuxiu,Wang, Qingmin
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p. 2477 - 2481
(2021/04/05)
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- Wittig Olefination Using Phosphonium Ion-Pair Reagents Incorporating an Endogenous Base
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Despite common perception, the use of strong bases in Wittig chemistry is utterly unnecessary: we report a series of novel ion-pair phosphonium carboxylate reagents which are essentially "storable ylides". These reagents are straightforwardly prepared in excellent yields, and their fluxional nature permits clean olefination of a broad range of aldehydes and even hemiacetals.
- Vetter, Anna C.,Gilheany, Declan G.,Nikitin, Kirill
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p. 1457 - 1462
(2021/03/08)
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- A photocatalyst-free photo-induced denitroalkylation of β-nitrostyrenes with 4-alkyl substituted Hantzsch esters at room temperature
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A photocatalyst-free stereoselectively photo-induced strategy for the denitroalkylation of β-nitrostyrenes using 4-alkyl substituted Hantzsch esters as the alkyl source under xenon lamp irradiation is developed. The reaction proceeds at room temperature and affords the corresponding products in moderate to excellent yields. The oxidant di-t-butyl peroxide serves as an efficient radical initiator under irradiation of a Xenon lamp, initiating alkyl radicals from the 4-alkyl substituted Hantzsch esters.
- Duan, Chunying,Hao, Xinyu,Jin, Kun,Li, Yaming,Wang, Jiaao,Zhang, Rong,Zhang, Siyu
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supporting information
(2020/02/18)
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- Energy Transfer from CdS QDs to a Photogenerated Pd Complex Enhances the Rate and Selectivity of a Pd-Photocatalyzed Heck Reaction
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This Article describes the design of a colloidal quantum dot (QD) photosensitizer for the Pd-photocatalyzed Heck coupling of styrene and iodocyclohexane to form 2-cyclohexylstyrene. In the presence of 0.05 mol % CdS QDs, which have an emission spectrum that overlaps the absorption spectrum of a key Pd(II)alkyl iodide intermediate, the reaction proceeds with 82% yield for the Heck product at 0.5 mol % loading of Pd catalyst; no product forms at this loading without a sensitizer. A radical trapping experiment and steady-state and transient optical spectroscopies indicate that the QDs transfer energy to a Pd(II)alkyl iodide intermediate, pushing the reaction toward a Pd(I) alkyl radical species that leads to the Heck coupled product, and suppressing undesired β-hydride elimination directly from the Pd(II)alkyl iodide. Functionalization of the surfaces of the QDs with isonicotinic acid increases the rate constant of this reaction by a factor of 2.4 by colocalizing the QD and the Pd-complex. The modularity and tunability of the QD core and surface make it a convenient and effective chromophore for this alternative mode of cooperative photocatalysis.
- Zhang, Zhengyi,Rogers, Cameron R.,Weiss, Emily A.
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supporting information
p. 495 - 501
(2020/01/03)
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- Dealkenylative Alkenylation: Formal σ-Bond Metathesis of Olefins
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The dealkenylative alkenylation of alkene C(sp3)?C(sp2) bonds has been an unexplored area for C?C bond formation. Herein 64 examples of β-alkylated styrene derivatives, synthesized through the reactions of readily accessible feedstock olefins with β-nitrostyrenes by ozone/FeII-mediated radical substitutions, are reported. These reactions proceed with good efficiencies and high stereoselectivities under mild reaction conditions and tolerate an array of functional groups. Also demonstrated is the applicability of the strategy through several synthetic transformations of the products, as well as the syntheses of the natural product iso-moracin and the drug (E)-metanicotine.
- Kwon, Ohyun,Sadykhov, Gusein,Swain, Manisha,Wang, Ruoxi
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supporting information
p. 17565 - 17571
(2020/09/01)
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- Copper-catalyzed oxidative decarboxylative alkylation of cinnamic acids with 4-alkyl-1,4-dihydropyridines
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We have developed a new oxidative decarboxylation of cinnamic acids with 4-alkyl-1,4-dihydropyridines to construct C(sp3)-C(sp2) bonds in the presence of copper catalyst and dicumyl peroxide (DCP). A variety of internal alkenes have been obtained with mild conditions, broad substrate scope and excellent functional group tolerance. This method has significant potential for application by using inexpensive and stable cinnamic acids instead of alkenyl halides and nitro-olefins. This journal is
- Zhang, Dong,Tang, Zi-Liang,Ouyang, Xuan-Hui,Song, Ren-Jie,Li, Jin-Heng
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supporting information
p. 14055 - 14058
(2020/11/20)
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- Photoinduced Deaminative Coupling of Alkylpyridium Salts with Terminal Arylalkynes
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A novel and simple Z-alkene synthesis by the photocatalyzed coupling reactions of alkylpyridium salts, which were prepared from primary amines, with terminal aryl alkynes at room temperature is reported here. A wide range of primary amines, which contain different functional groups, were tolerated under these conditions. The mild reaction conditions, broad substrate scope, functional group tolerance, and operational simplicity make this deaminative coupling reaction a valuable method in organic syntheses.
- Lai, Shu-Zhen,Yang, Yu-Ming,Xu, Hai,Tang, Zhen-Yu,Luo, Zhuangzhu
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p. 15638 - 15644
(2020/11/13)
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- Vinyl Sulfonium Salts as the Radical Acceptor for Metal-Free Decarboxylative Alkenylation
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Vinyl sulfonium salts typically act as an electrophilic Michael acceptor, thus initiating many tandem cyclization reactions. Herein, we disclosed the novel reactivity of vinyl sulfonium salts as a radical acceptor. Using redox-active ester as an alkyl rad
- Zhang, Yu-Lan,Yang, Lei,Wu, Jie,Zhu, Chunyin,Wang, Peng
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p. 7768 - 7772
(2020/10/09)
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- Stereoselective Chromium-Catalyzed Semi-Hydrogenation of Alkynes
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Chromium complexes have found very little applications as hydrogenation catalysts. Here, we report a Cr-catalyzed semi-hydrogenation of internal alkynes to the corresponding Z-alkenes with good stereocontrol (up to 99/1 for dialkyl alkynes). The catalyst comprises the commercial reagents chromium(III) acetylacetonate, Cr(acac)3, and diisobutylaluminium hydride, DIBAL?H, in THF. The semi-hydrogenation operates at mild conditions (1-5 bar H2, 30 °C).
- Gregori, Bernhard J.,Nowakowski, Michal,Schoch, Anke,P?llath, Simon,Zweck, Josef,Bauer, Matthias,Jacobi von Wangelin, Axel
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p. 5359 - 5363
(2020/09/03)
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- Photocatalytic dual decarboxylative alkenylation mediated by triphenylphosphine and sodium iodide
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An efficient photocatalytic dual decarboxylative alkenylation of α,β-unsaturated carboxylic acids and alkyl N-hydroxyphthalimide (NHP) esters mediated by triphenylphosphine and sodium iodide has been developed. This protocol proceeds under 456-nanometer irradiation by visible blue light in the absence of transition metals or organic dye based photoredox catalysts. The reaction is successfully applied to a wide range of redox-active esters derived from aliphatic carboxylic acids (1°, 2° and 3°) and α-amino acids, enabling transformations of diverse α,β-unsaturated carboxylic acids to α,β-alkylated styrenes with high efficiency and excellent selectivity under mild conditions.
- Li, Jin-Heng,Li, Yang,Lv, Gui-Fen,Wang, Hong-Yu,Zhong, Long-Jin
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supporting information
p. 5589 - 5593
(2020/08/21)
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- A Bidentate Ru(II)-NC Complex as a Catalyst for Semihydrogenation of Alkynes to (E)-Alkenes with Ethanol
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Four Ru(II)-NC complexes were tested as catalysts for semihydrogenation of internal alkynes to (E)-alkenes with ethanol, and the complex {(C5H4N)(C6H4)}RuCl(CO)(PPh3)2 (1a) showed the highest activity. The reactions proceeded well with 1 mol % catalyst loading and 0.1 equiv of t-BuONa at 110 °C for 1 h, and 32 alkenes were synthesized with excellent E:Z selectivity. This is the first ruthenium-catalyzed semihydrogenation of internal alkynes to (E)-alkenes using ethanol as the hydrogen donor.
- Chen, Dafa,Gong, Dawei,Hu, Bowen,Kong, Degong,Xia, Haiping,Yang, Weiwei
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- Method for synthesizing trans-olefin compound
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The invention discloses a trans-olefin compound synthesis method, which comprises: carrying out a heating reaction on an alkyne compound represented by a general formula (I), a reducing agent and a solvent to obtain a trans-olefin compound represented by a general formula (II), wherein the synthesis route is as follows: R1 and R2 are independently selected from hydrogen, alkyl, cycloalkyl or aryl;wherein the reducing agent is a sulfur-containing compound and is selected from at least one of thioacetamide, N,N-dimethyl dithiocarbamate dimethyl ammonium salt, dimethyl amino sodium dithioformatedihydrate, potassium ethyl xanthate and potassium isopropyl xanthate. According to the method, a cheap, efficient and safe reducing agent is utilized to realize high-selectivity reduction of alkyne to prepare trans-olefin under the condition of no transition metal catalysis, so that the method is simple and easy to implement, wide in substrate application range and easy to realize industrialization.
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Paragraph 0055-0058
(2020/06/20)
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- Covalent Organic Framework as a Heterogeneous Ligand for the Regioselective Oxidative Heck Reaction
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A simple imine-based covalent organic framework (COF) as heterogeneous ligand for PdII-promoted Heck reaction is reported. Good regioselectivity for a wide range of electronically unbiased olefins is obtained (linear/branched >100:1 in most cases). Related tests and density functional theory calculations are used to explore the reason underlying the high selectivity. This research opens a route for COF as an intriguing platform to control regioselectivity catalysis.
- Han, Jiyao,Sun, Xiaowei,Wang, Xiao,Wang, Qiong,Hou, Shenghuai,Song, Xin,Wei, Yingqin,Wang, Rongyu,Ji, Wenhua
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supporting information
p. 1480 - 1484
(2020/03/13)
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- Reductive Difunctionalization of Aryl Alkenes with Sodium Metal and Reduction-Resistant Alkoxy-Substituted Electrophiles
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A general method for alkali-metal-promoted reductive difunctionalization of alkenes has been developed by means of reduction-resistant alkoxy-substituted electrophiles. A series of 1,2-diboration and 1,2-dicarbofunctionalization products can be synthesize
- Fukazawa, Mizuki,Nogi, Keisuke,Sasamori, Takahiro,Takahashi, Fumiya,Yorimitsu, Hideki
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supporting information
(2020/03/13)
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- Iron-Catalyzed Cross-Coupling of Alkynyl and Styrenyl Chlorides with Alkyl Grignard Reagents in Batch and Flow
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Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables the formation of Csp?Csp3 and Csp2?Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity.
- Deng, Yuchao,Wei, Xiao-Jing,Wang, Xiao,Sun, Yuhan,No?l, Timothy
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p. 14532 - 14535
(2019/11/21)
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- Visible Light-Driven, Room Temperature Heck-Type Reaction of Alkyl Halides with Styrene Derivatives Catalyzed by B12 Complex
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A visible light driven Heck-type coupling reaction of alkyl halides with styrene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ru(bpy)3]Cl2 photosensitizer at room temperature is reported. The catalytic efficiencies of the B12 catalyst were compared to that of other cobalt complexes such as cobaloxime. Various control experiments supported a radical-based mechanism similar to those for typical B12 model reactions. A unique coupling reaction combined with 1,2-migration of the functional group is also reported. Mild reaction conditions using an environmentally benign cobalt catalyst derived from the natural B12 provided a practical protocol for the synthetic organic chemistry of the B12 catalyzed reaction system. (Figure presented.).
- Chen, Li,Hisaeda, Yoshio,Shimakoshi, Hisashi
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p. 2877 - 2884
(2019/04/03)
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- Oxidative Addition to Palladium(0) Made Easy through Photoexcited-State Metal Catalysis: Experiment and Computation
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Visible-light induced, palladium catalyzed alkylations of α,β-unsaturated acids with unactivated alkyl bromides are described. A variety of primary, secondary, and tertiary alkyl bromides are activated by the photoexcited palladium metal catalyst to provide a series of olefins at room temperature under mild reaction conditions. Mechanistic investigations and density functional theory (DFT) studies suggest that a photoinduced inner-sphere mechanism is operative in which a barrierless, single-electron transfer oxidative addition of the alkyl halide to Pd0 is key for the efficient transformation.
- Kancherla, Rajesh,Muralirajan, Krishnamoorthy,Maity, Bholanath,Zhu, Chen,Krach, Patricia E.,Cavallo, Luigi,Rueping, Magnus
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supporting information
p. 3412 - 3416
(2019/01/16)
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- Visible light-driven cross-coupling reactions of alkyl halides with phenylacetylene derivatives for C(sp3)-C(sp) bond formation catalyzed by a B12 complex
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Visible light-driven cross-coupling reactions of alkyl halides with phenylacetylene and its derivatives catalyzed by the cobalamin derivative (B12) with the [Ir(dtbbpy)(ppy)2]PF6 photocatalyst at room temperature are reported. The robust B12 catalyst and Ir photocatalyst provided high turnover numbers of over 33?000 for the reactions.
- Chen, Li,Kametani, Yohei,Imamura, Kenji,Abe, Tsukasa,Shiota, Yoshihito,Yoshizawa, Kazunari,Hisaeda, Yoshio,Shimakoshi, Hisashi
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supporting information
p. 13070 - 13073
(2019/11/11)
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- Transition-Metal-Free Deaminative Vinylation of Alkylamines
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The amino group is one of the most fundamental structural motifs in natural products and synthetic chemicals. However, amines potential as effective alkylating agents in organic synthesis is still problematic. A unified strategy has been established for deaminative vinylation of the alkylamines with vinyl boronic acids by C?N bond activation under catalyst-free conditions. The key to the high reactivity is the utilization of pyridinium salt-activated alkylamines, with a base as a promoter. The transformation exhibits good functional group compatibility, and includes inexpensive primary amine feedstocks and amino acids. The proposed method can serve as a powerful synthetic method for late-stage modification of complex compounds. Mechanistic experiments suggest that free radical processes are involved in this system. (Figure presented.).
- Hu, Jiefeng,Cheng, Bo,Yang, Xianyu,Loh, Teck-Peng
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p. 4902 - 4908
(2019/09/13)
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- Stereodivergent synthesis of alkenes by controllable syn-/anti-fragmentation of β-hydroxysulfonyl intermediates
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The reduction of the carbonyl group in acylated trifluoroethyl alkanesulfonates follows the Felkin-Ahn selectivity, and the so-formed diastereomeric β-hydroxysulfonyl intermediates undergo syn- and anti-fragmentation, depending on the reaction conditions. In effect, isomeric E- and Z-alkenes are formed in a stereodivergent manner, which mimics the mechanistic manifold of the Peterson olefination.
- Górski, Bartosz,Basiak, Dariusz,Grzesiński, ?ukasz,Barbasiewicz, Micha?
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supporting information
p. 7660 - 7663
(2019/08/30)
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- Xanthate-mediated synthesis of (E)-alkenes by semi-hydrogenation of alkynes using water as the hydrogen donor
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Semi-hydrogenation of alkynes is one of the most widely used methods for obtaining alkenes in laboratory preparation and in industry. Transition metal catalysts have been extensively studied for this transformation, but the tolerance of functional groups, such as pyridine,-OH,-NH2,-Bpin, and halides, and the toxicity of the trace amount of transition metal catalysts are still highly challenging. In this study, we report a general and robust strategy to achieve the semi-hydrogenation of alkynes using inexpensive and commercially available xanthate as the mediator. Mechanism studies support a non-radical process and H2O acts as the hydrogen donor.
- Luo, Xianglin,Chen, Xiuwen,Chen, Lu,Zhang, Kun,Li, Yibiao
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supporting information
p. 2170 - 2173
(2019/02/24)
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- Iterative synthesis of alkenes by insertion of lithiated epoxides into boronic esters
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The insertion of lithiated epoxides into boronic esters followed by thermal syn-elimination provides a stereospecific entry to alkenes. This process avoids transition metals and is amenable to iteration to provide higher substitution patterns.
- Bojaryn, Kevin,Fritsch, Stefan,Hirschhaüser, Christoph
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supporting information
p. 2218 - 2222
(2019/04/10)
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- Selective Syntheses of Z-Alkenes via Photocatalyzed Decarboxylative Coupling of N-Hydroxyphthalimide Esters with Terminal Arylalkynes
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A novel, efficient Z-alkene synthesis via photocatalyzed decarboxylative couplings between terminal aryl alkynes and alkyl N-hydroxyphthalimide (NHPI) esters, which are derived from aliphatic carboxylic acids, is described. A wide range of primary, secondary, and tertiary carboxylates as well as α-amino acid and α-oxyacid-derived esters were employed as suitable substrates. The mild reaction conditions, broad substrate scope, functional group tolerance, and operational simplicity make this decarboxylative coupling reaction a valuable method in organic syntheses.
- Dai, Guo-Li,Lai, Shu-Zhen,Luo, Zhuangzhu,Tang, Zhen-Yu
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supporting information
p. 2269 - 2272
(2019/04/10)
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- Method for synthesizing cis-olefin by catalyzing decarboxylation coupling reaction of NHP ester and aryl-terminated alkyne with iridium
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The invention provides a method for synthesizing Z-selective olefin by catalyzing a decarboxylation coupling reaction of an NHP ester and aryl-terminated alkyne with iridium. The aryl-terminated alkyne and its derivative and the NHP ester undergo a one-po
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Paragraph 0065-0067; 0099-0100; 0103-0138
(2019/02/13)
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- A hydrate salt-promoted reductive coupling reaction of nitrodienes with unactivated alkenes
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Transition metal-catalyzed reductive coupling has emerged as a powerful method for the construction of C-C bonds. Herein, a crystalline hydrate, Na2HPO4·7H2O, has been disclosed as an effective promoter for the reductive c
- Zhang, Mengmeng,Yang, Liming,Tian, Chao,Zhou, Meng,An, Guanghui,Li, Guangming
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p. 2258 - 2264
(2019/02/27)
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- Multicatalytic Stereoselective Synthesis of Highly Substituted Alkenes by Sequential Isomerization/Cross-Coupling Reactions
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Starting from readily available alkenyl methyl ethers, the stereoselective preparation of highly substituted alkenes by two complementary multicatalytic sequential isomerization/cross-coupling sequences is described. Both elementary steps of these sequences are challenging processes when considered independently. A cationic iridium catalyst was identified for the stereoselective isomerization of allyl methyl ethers and was found to be compatible with a nickel catalyst for the subsequent cross-coupling of the in situ generated methyl vinyl ethers with various Grignard reagents. The method is compatible with sensitive functional groups and a multitude of olefinic substitution patterns to deliver products with high control of the newly generated C=C bond. A highly enantioselective variant of this [Ir/Ni] sequence has been established using a chiral iridium precatalyst. A complementary [Pd/Ni] catalytic sequence has been optimized for alkenyl methyl ethers with a remote C=C bond. The final alkenes were isolated with a lower level of stereocontrol. Upon proper choice of the Grignard reagent, we demonstrated that C(sp2) - C(sp2) and C(sp2) - C(sp3) bonds can be constructed with both systems delivering products that would be difficult to access by conventional methods.
- Romano, Ciro,Mazet, Clément
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supporting information
p. 4743 - 4750
(2018/04/10)
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- Photo-induced Decarboxylative Heck-Type Coupling of Unactivated Aliphatic Acids and Terminal Alkenes in the Absence of Sacrificial Hydrogen Acceptors
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1,2-Disubstituted alkenes such as vinyl arenes, vinyl silanes, and vinyl boronates are among the most versatile building blocks that can be found in every sector of chemical science. We herein report a noble-metal-free method of accessing such olefins through a photo-induced decarboxylative Heck-type coupling using alkyl carboxylic acids, one of the most ubiquitous building blocks, as the feedstocks. This transformation was achieved in the absence of external oxidants through the synergistic combination of an organo photo-redox catalyst and a cobaloxime catalyst, with H2 and CO2 as the only byproducts. Both control experiments and DFT calculations supported a radical-based mechanism, which eventually led to the development of a selective three-component coupling of aliphatic carboxylic acids, acrylates, and vinyl arenes. More than 90 olefins across a wide range of functionalities were effectively synthesized with this simple protocol.
- Cao, Hui,Jiang, Heming,Feng, Hongyu,Kwan, Jeric Mun Chung,Liu, Xiaogang,Wu, Jie
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supporting information
p. 16360 - 16367
(2018/11/27)
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- Iron-Catalyzed Vinylic C?H Alkylation with Alkyl Peroxides
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A variety of alkyl peresters and alkyl diacyl peroxides, which are readily accessible from carboxylic acids, are utilized as general primary, secondary, and tertiary alkylating reagents for iron-catalyzed vinylic C?H alkylation of vinyl arenes, dienes, and 1,3-enynes. This transformation affords olefinic products in up to 98 % yield with high E/Z values. A broad range of functionalities, including carboxyl, boronic acid, methoxy, ester, amino, and halides, are tolerated. This protocol provides a facile approach to some olefins that are difficult to access, and hence, offers an alternative to existing systems. The synthetic utility of this method is demonstrated by late-stage functionalization of selected natural-product derivatives.
- Ge, Liang,Jian, Wujun,Zhou, Huan,Chen, Shaowei,Ye, Changqing,Yu, Fei,Qian, Bo,Li, Yajun,Bao, Hongli
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supporting information
p. 2522 - 2528
(2018/08/01)
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- Olefination with Sulfonyl Halides and Esters: E-Selective Synthesis of Alkenes from Semistabilized Carbanion Precursors
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Carbanions of sulfonyl halides and activated sulfonates add to carbonyl compounds, and so-formed aldol-type adducts spontaneously fragment into olefins. This transformation mimics the one-pot Julia olefination with (hetero)aryl sulfones, but the mechanism of fragmentation involves a four-membered intermediate, typical for reactivity of phosphorus reagents. Moreover, in contrast to the reactions of sulfones, sulfonates of fluorinated alcohols (TFE and HFI) produce byproducts that are easily removed during workup. In our report, we focus on reactions of unstabilized and semistabilized carbanion precursors: alkylsulfonates, and allyl- and benzylsulfonates, respectively. In particular for semistabilized systems, olefins were synthesized as predominant E isomers in good yields. The presented studies reveal that optimal reaction conditions, including the type of base and alcohol groups of the sulfonates, are different depending on stabilization of the carbanion precursors and structure of the carbonyl substrates. The practical synthetic guide is supplemented with a discussion of the mechanism, based on reactivity studies of intermediates and identification of side-products.
- Górski, Bartosz,Basiak, Dariusz,Talko, Alicja,Basak, Tymoteusz,Mazurek, Tomasz,Barbasiewicz, Micha?
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supporting information
p. 1774 - 1784
(2018/04/27)
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- Palladium/Light induced radical alkenylation and allylation of alkyl iodides using alkenyl and allylic sulfones
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Alkenylation and allylation of alkyl iodides with alkenyl and allyl sulfones, respectively, took place under Pd/photoirradiation system. The initial alkyl radical, derived from a single electron transfer between Pd(0) and RI, underwent the title transformations. Pd(0) was regenerated through a reductive elimination of PhSO2PdI, which is formed by the combination of the sulfonyl radical and the palladium radical. The addition of water was effective, presumably by pushing the equilibrium through hydrolysis of PhSO2I.
- Sumino, Shuhei,Uno, Misae,Huang, Hsin-Ju,Wu, Yen-Ku,Ryu, Ilhyong
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supporting information
p. 1078 - 1081
(2018/02/23)
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- Irradiation-Induced Palladium-Catalyzed Decarboxylative Heck Reaction of Aliphatic N-(Acyloxy)phthalimides at Room Temperature
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It is reported that Pd(PPh3)2Cl2 in combination with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) under irradiation of blue LEDs efficiently catalyzes a decarboxylative Heck reaction of vinyl arenes and vinyl heteroarenes with aliphatic N-(acyloxy)phthalimides at room temperature. A broad scope of secondary, tertiary, and quaternary carboxylates, including α-amino acid derived esters, can be applied as amenable substrates with high stereoselectivity. The experimental observation was explained by excitation-state reactivity of the palladium complex under irradiation to induce single-electron transfer to activate N-(acyloxy)phthalimides, and to suppress undesired β-hydride elimination of alkyl palladium intermediates.
- Wang, Guang-Zu,Shang, Rui,Fu, Yao
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p. 888 - 891
(2018/02/10)
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- Silver-catalyzed decarboxylative C(sp2)-C(sp3) coupling reactions: Via a radical mechanism
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A silver catalyzed decarboxylative C(sp2)-C(sp3) coupling of vinylic carboxylic acids with alcohols, alkylbenzenes, cycloalkanes and cyclic ethers was developed by using DTBP as an oxidant. This reaction tolerates a wide range of substrates, and products are obtained in good to excellent yields. The reaction also shows good stereoselectivity, and only trans-isomers are obtained. In addition, a radical pathway would be involved to facilitate this decarboxylative C(sp2)-C(sp3) coupling reaction.
- Fang, Zhongxue,Wei, Chenlong,Lin, Jing,Liu, Zhenhua,Wang, Wei,Xu, Chenshu,Wang, Xuemin,Wang, Yu
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supporting information
p. 9974 - 9978
(2017/12/26)
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- Photoinduced, Copper-Promoted Regio- and Stereoselective Decarboxylative Alkylation of α,β-Unsaturated Acids with Alkyl Iodides
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The first example of UV light-induced, copper-catalyzed regio- and stereoselective decarboxylative coupling of α,β-unsaturated acids with alkyl iodides was reported. Under standard conditions, the 1°, 2°, and 3° alkyl iodides proceeded smoothly with the E-selective alkenes obtained in uniformly good yields and high stereoselectivities.
- Wang, Chao,Lei, Yingjie,Guo, Mengzhun,Shang, Qinyu,Liu, Hong,Xu, Zhaoqing,Wang, Rui
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supporting information
p. 6412 - 6415
(2017/12/08)
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- Photoredox catalysis enabled alkylation of alkenyl carboxylic acids with: N -(acyloxy)phthalimide via dual decarboxylation
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A ruthenium based photoredox catalyst in combination with a substoichiometric amount of 1,4-diazabicyclo[2.2.2]octane (DABCO) efficiently catalyzed dual decarboxylative couplings between alkenyl carboxylic acids and N-(acyloxy)phthalimides derived from aliphatic carboxylic acids, delivering alkylated styrene derivatives in a high regio- and stereo-selective manner under mild reaction conditions. Various types of secondary, tertiary, and quaternary aliphatic carboxylic acids as well as α-amino acids can be used as suitable substrates. Mechanistic analysis suggested that the reaction proceeds through a radical mechanism mediated by a Ru(i)/Ru(ii) catalytic cycle with DABCO acting both as the base and the co-catalyst for single electron transfer.
- Xu, Kun,Tan, Zhoumei,Zhang, Haonan,Liu, Juanli,Zhang, Sheng,Wang, Zhiqiang
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supporting information
p. 10719 - 10722
(2017/10/06)
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- Conjugated Microporous Polymer as Heterogeneous Ligand for Highly Selective Oxidative Heck Reaction
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A series of pyridine-type ligands containing C C bonds were designed and synthesized for selective oxidative Heck reaction. These ligands were utilized as functional units and integrated into the skeleton of conjugated microporous polymers. 6,6′-diiodo-2,2′-bipyridine and 1,3,5-triethynylbenzene were polycondensed via Sonogashira cross-coupling strategy to afford CMP-1 material. The resultant CMP-1 was used as a heterogeneous catalytic ligand for the PdII-catalyzed oxidative Heck reaction with high linear selectivity. The linear selectivity of CMP-1 is about 30 times higher than that of bipyridine-based monomer ligand. This work opens a new front of using CMP as an intriguing platform for developing highly efficient catalysts in controlling the regioselectivity in organic reactions.
- Zhou, Yun-Bing,Wang, Yu-Qing,Ning, Li-Chao,Ding, Zong-Cang,Wang, Wen-Long,Ding, Cheng-Ke,Li, Ren-Hao,Chen, Jun-Jia,Lu, Xin,Ding, Yun-Jie,Zhan, Zhuang-Ping
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supporting information
p. 3966 - 3969
(2017/03/27)
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- Thiophene-Alkyne-Based CMPs as Highly Selective Regulators for Oxidative Heck Reaction
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Thiophenes containing an adjacent C≡C group as ligands for PdII-promoted organic reactions are reported for the first time. These ligands were utilized as catalytic sites and integrated into the skeleton of conjugated microporous polymers. By e
- Li, Ren-Hao,Ding, Zong-Cang,Li, Cun-Yao,Chen, Jun-Jia,Zhou, Yun-Bing,An, Xiao-Ming,Ding, Yun-Jie,Zhan, Zhuang-Ping
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p. 4432 - 4435
(2017/09/11)
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- Visible Light-Induced Room-Temperature Heck Reaction of Functionalized Alkyl Halides with Vinyl Arenes/Heteroarenes
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The first visible light-induced Pd-catalyzed Heck reaction of α-heteroatom substituted alkyl iodides and -bromides with vinyl arenes/heteroarenes has been developed. This transformation efficiently proceeds at room temperature and enables synthesis of valuable functionalized allylic systems, such as allylic silanes, boronates, germanes, stannanes, pivalates, phosphonates, phthalimides, and tosylates from the corresponding α-substituted methyl iodides. Notably, synthesis of the latter substrates failed under existing thermally induced Pd-catalyzed conditions, which highlights the importance of visible light for this transformation.
- Kurandina, Daria,Parasram, Marvin,Gevorgyan, Vladimir
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supporting information
p. 14212 - 14216
(2017/10/13)
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- Hydroalkylation of terminal aryl alkynes with alkyl diacyl peroxides
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A photo and nickel co-catalyzed hydroalkylation of terminal aryl alkynes enabled Z-preferred olefin synthesis has been developed under mild conditions. Alkyl diacyl peroxides were utilized as a new type of alkylation reagents and afforded Z-olefins as the major products in moderate to good yields.
- Li, Yougui,Ge, Liang,Qian, Bo,Babu, Kaki Raveendra,Bao, Hongli
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supporting information
p. 5677 - 5680
(2016/11/28)
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- Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts
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Carbon-supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant-free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt0 sites on the Pt metal particles are responsible for the rate-limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method. Olefination of alcohols: The first heterogeneous catalytic terminal and internal olefination of primary alcohols and methylenation of secondary alcohols with sulfones, a reusable carbon-supported Pt catalyst, and KOtBu is reported (see scheme).
- Hakim Siddiki,Touchy, Abeda Sultana,Kon, Kenichi,Shimizu, Ken-Ichi
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p. 6111 - 6119
(2016/04/26)
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- Metal-Free Microwave-Assisted Decarboxylative Elimination for the Synthesis of Olefins
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A metal-free efficient synthesis of olefins via microwave-assisted direct decarboxylative elimination of arylacetic acids is described. This reaction, using commercially available reagent PIFA as oxidant, readily provides a variety of desired products in moderate to good yields.
- Wu, Shu-Wei,Liu, Jia-Li,Liu, Feng
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supporting information
p. 1 - 3
(2016/01/15)
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- Nickel-Catalyzed Denitrated Coupling Reaction of Nitroalkenes with Aliphatic and Aromatic Alkenes
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A simple and practical denitrated coupling reaction of nitroalkenes with various alkenes using a nickel catalyst and triethoxysilane [(EtO)3SiH] as reducing agent was achieved. Under mild reaction conditions, both aliphatic and aromatic alkenes could react with nitroalkenes to obtain a series of olefins with different functional groups in satisfactory yields under an air atmosphere, which were previously difficult or impossible to access. (Figure presented.).
- Zhang, Na,Quan, Zheng-Jun,Wang, Xi-Cun
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supporting information
p. 3179 - 3183
(2016/10/21)
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- Design and synthesis of the basic Cu-doped zeolite X catalyst with high activity in oxidative coupling reactions
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The decarboxylative coupling of cinnamic acids with alcohols and the oxidative coupling of alkenes with aldehydes are typical organic reactions. Considering the characteristics and mechanisms of the reactions, the Cu-doped zeolite-X catalyst (Cu-X) with Lewis basic sites was synthesized and used for the two reactions. Compared with Cu, Cu2O, and CuBr2 catalysts (4-21%), the Cu-X catalyst (99%) shows extraordinary high activity in the decarboxylative coupling of cinnamic acids with alcohols. In addition, the Cu-X catalyst presents excellent performance in the oxidative coupling of alkenes with aldehydes. The strong interaction between Cu+ and the zeolite framework benefits the transformation of Cu2+ and Cu+ in the redox process, enhancing the reaction activity. More importantly, the Lewis basic sites on the Cu-X catalyst could favor the adsorption of the cinnamic acid, resulting in electron-rich density in the C=C bond, and therefore greatly improving the reaction activity.
- Chen, Shengchun,Shao, Zhen,Fang, Zhongxue,Chen, Qun,Tang, Ting,Fu, Wenqian,Zhang, Lei,Tang, Tiandi
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- A transition-metal-free Heck-type reaction between alkenes and alkyl iodides enabled by light in water
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A transition-metal-free coupling protocol between various alkenes and non-activated alkyl iodides has been developed by using photoenergy in water for the first time. Under UV irradiation and basic aqueous conditions, various alkenes efficiently couple with a wide range of non-activated alkyl iodides. A tentative mechanism, which involves an atom transfer radical addition process, for the coupling is proposed.
- Liu, Wenbo,Li, Lu,Chen, Zhengwang,Li, Chao-Jun
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supporting information
p. 6170 - 6174
(2015/06/08)
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- Copper-catalyzed oxidative alkenylation of C(sp3)-H bonds via benzyl or alkyl radical addition to β-nitrostyrenes
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A new method for the preparation of (E)-β-alkylstyrene derivatives has been developed via the addition of a benzyl or alkyl radical to β-nitrostyrenes using di-tert-butyl peroxide (DTBP) as the oxidant in the presence of Cu powder catalyst. The C-H bonds in various toluene derivatives, ethers, alkanes and alcohols were successfully converted into C-C bonds to yield the corresponding (E)-β-alkylstyrene derivatives in moderate to good yields.
- Guo, Shengrong,Yuan, Yanqin,Xiang, Jiannan
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supporting information
p. 3093 - 3097
(2015/04/14)
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