- Catalytic Enantioselective Synthesis of β-Allenyl Boronic Esters by Conjunctive Cross-Coupling with Propargylic Carbonates
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Enantioselective conjunctive cross-coupling with propargylic carbonates affords β-boryl allenes as the reaction product. The reaction is found to proceed through the intermediacy of dimethoxyboronate complexes that are generated in situ by a strain-induce
- Aparece, Mark D.,Hu, Weipeng,Morken, James P.
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- Catalyst-Free Rearrangement of Allenyl Aryldiazoacetates into 1,5-Dihydro-4H-pyrazol-4-ones
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Phenylpropargyl diazoacetates exist in equilibrium with 1-phenyl-1,2-dien-1-yl diazoacetate - allenes that are rapidly formed at room temperature through 1,3-acyloxy migration catalyzed by gold(I) or gold(III) compounds, and these catalysts react solely with the π-donor rather than with the diazo group. The product allene of the aryldiazoacetates undergoes rearrangement that is not catalyzed by gold in which the terminal nitrogen of the diazo functional group adds to the central carbon of the allene, initiating a sequence of bond-forming reactions, resulting in the production of 1,5-dihydro-4H-pyrazol-4-ones in good yields. These 1,5-dihydro-4H-pyrazol-4-ones undergo intramolecular 1,3-acyl migration to form an equilibrium mixture and can quantitatively transfer the acyl group to an external nucleophile with formation of 4-hydroxypyrazoles. Reactions of phenylpropargyl phenyldiazoacetates catalyzed by cationic gold complexes are initiated at the diazo functional group to form a gold carbene whose subsequent cascade process (intramolecular addition, then aromatic substitution) results in the formation of a product that is uniquely characteristic of this pathway.
- Marichev, Kostiantyn O.,Qiu, Huang,Offield, Austin C.,Arman, Hadi,Doyle, Michael P.
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- Diverse Pathways in Catalytic Reactions of Propargyl Aryldiazoacetates: Selectivity between Three Reaction Sites
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Three catalyst-dependent divergent reaction pathways for reactions of propargyl aryldiazoacetates are disclosed. Transition metal catalysts including those of rhodium(II), palladium(0 and II), silver(I), mercury(II), copper(I and II), platinum(II), and cationic gold(I) are effective for reactions that proceed through dinitrogen extrusion, carbene/alkyne metathesis, and aromatic substitution to form fused indeno-furanones, and use of tetrakis(acetonitrile)copper(I) provides indeno-furanones in the highest product yields. A Lewis acid catalyzed pathway that forms furan-2-ones is uncovered with FeCl3, ZnBr2, and BF3·Et2O as catalysts that proceed through activation of the aryldiazoacetate ester for arylpropargyl cation dissociation followed by recombination through cation addition to the diazo carbon. Neutral gold catalysts selectively activate the triple bond of propargyl aryldiazoacetates, resulting in the formation of allenic aryldiazoesters that further undergo uncatalyzed rearrangement.
- Qiu, Huang,Deng, Yifan,Marichev, Kostiantyn O.,Doyle, Michael P.
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- Electrochemical fluorosulfonylation of styrenes
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An environmentally friendly and efficient electrochemical fluorosulfonylation of styrenes has been developed. With the use of sulfonylhydrazides and triethylamine trihydrofluoride, a diverse array of β-fluorosulfones could be readily obtained. This reaction features mild conditions and a broad substrate scope, which could also be conveniently extended to a gram-scale preparation.
- Jiang, Yi-Min,Yu, Yi,Wu, Shao-Fen,Yan, Hong,Yuan, Yaofeng,Ye, Ke-Yin
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supporting information
p. 11481 - 11484
(2021/11/16)
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- Electrochemistry enabled selective vicinal fluorosulfenylation and fluorosulfoxidation of alkenes
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Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science. The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H2O in the reaction mixture.
- Jiang, Yimin,Shi, Zhaojiang,Wu, Jinnan,Wu, Shaofen,Ye, Keyin,Yu, Yi,Yuan, Yaofeng
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supporting information
(2021/11/17)
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- Dual Photoredox/Nickel-Catalyzed 1,4-Sulfonylarylation of 1,3-Enynes with Sulfinate Salts and Aryl Halides: Entry into Tetrasubstituted Allenes
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A radical-mediated three-component 1,4-sulfonylarylation of 1,3-enynes with aryl iodides and sulfinate salts using cooperative photoredox/nickel catalysis is described. This protocol enables the synthesis of tetrasubstituted sulfonyl-containing allenes under redox-neutral conditions and provides a versatile 1,3-enyne 1,4-difunctionalization platform for the synthesis of a diverse range of tetrasubstituted allenes with high chemo- and regioselectivities, excellent functional group tolerance, and a broad substrate scope.
- Xu, Ting,Wu, Shuang,Zhang, Quan-Na,Wu, You,Hu, Ming,Li, Jin-Heng
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supporting information
p. 8455 - 8459
(2021/11/01)
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- Stereo- And Regioselective cis-Hydrophosphorylation of 1,3-Enynes Enabled by the Visible-Light Irradiation of NiCl2(PPh3)2
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Described herein is a stereo- and regioselective cis-hydrophosphorylation reaction of the internal alkyne of 1,3-enynes that accesses various 1,3-dienes in good isolated yields. The visible-light irradiation of NiCl2(PPh3)2 allows the generation of highly reactive nickel(II)-phosphorus species that subsequently migrate into the internal alkyne of the 1,3-enynes and protonate the resulting vinyl nickel species, leading to various phosphinoyl 1,3-butadienes under mild reaction conditions.
- Hou, Hong,Zhou, Bing,Wang, Jiawei,Zhao, Dengyang,Sun, Duhao,Chen, Xiaoyun,Han, Ying,Yan, Chaoguo,Shi, Yaocheng,Zhu, Shaoqun
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supporting information
p. 2981 - 2987
(2021/05/05)
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- Gold catalyzed efficient preparation of dihydrobenzofuran from 1,3-enyne and phenol
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A gold catalyzed formal intermolecular [2+3] cyclo-coupling of 1,3-enynes with phenols was developed to prepare dihydrobenzofuran derivatives with the addition of 2,6-dichloropyridine N-oxide, in which, a highly ortho-selective phenol SEAr functionalizati
- Wang, Yu-Jiang,Zhang, Yuan,Qiang, Zou,Liang, Jia-Ying,Chen, Zili
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supporting information
p. 12607 - 12610
(2021/12/07)
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- Asymmetric Wacker-Type Oxyallenylation and Azaallenylation of Cyclic Alkenes
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Palladium-catalyzed three-component carboetherification of cyclic alkenes proceeded to give trans adducts exclusively with excellent enantioselectivity through a Wacker-type pathway. The reaction is also applicable to other oxygen nucleophiles, such as water, phenols, and carboxylic acids, as well as some electron-poor aryl amines.
- Teng, Shenghan,Jiao, Zhiwei,Chi, Yonggui Robin,Zhou, Jianrong Steve
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supporting information
p. 2246 - 2250
(2020/01/02)
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- Fe-Catalyzed Selective Cyclopropanation of Enynes under Photochemical or Thermal Conditions
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The nucleophilic Fe-complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the cyclopropanation of enynes to substituted propargyl cyclopropanes using diazoesters as carbene surrogates. The catalyst can be activated either thermally in the presence of catalytic amounts of 4-nitroanisole or under photochemical conditions. Cyclopropanation occurs selectively at the enyne moiety; alternative olefinic moieties remain intact.
- Picher, Marie-Idrissa,Plietker, Bernd
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p. 340 - 344
(2020/01/11)
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- Preparation of Chiral Allenes through Pd-Catalyzed Intermolecular Hydroamination of Conjugated Enynes: Enantioselective Synthesis Enabled by Catalyst Design
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In this study, we establish that conjugated enynes undergo selective 1,4-hydroamination under Pd catalysis to deliver chiral allenes with pendant allylic amines. Several primary and secondary aliphatic and aryl-substituted amines couple with a wide range of mono- and disubstituted enynes in a nonenantioselective reaction where DPEphos serves as the ligand for Pd. Benzophenone imine acts as an ammonia surrogate to afford primary amines in a two-step/one-pot process. Examination of chiral catalysts revealed a high degree of reversibility in the C-N bond formation that negatively impacted enantioselectivity. Consequently, an electron-poor ferrocenyl-PHOX ligand was developed to enable efficient and enantioselective enyne hydroamination.
- Adamson, Nathan J.,Jeddi, Haleh,Malcolmson, Steven J.
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supporting information
p. 8574 - 8583
(2019/06/04)
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- Triple-Bond Insertion Triggers Highly Regioselective 1,4-Aminomethylamination of 1,3-Enynes with Aminals Enabled by Pd-Catalyzed C-N Bond Activation
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A highly chemo- and regioselective 1,4-aminomethylamination of simple enynes with aminals to allenic 1,5-diamines by taking advantage of C-N bond activation has been reported. The reaction proceeds under mild reaction conditions and can be performed under
- Zhang, Yanchen,Yu, Bangkui,Gao, Binjian,Zhang, Tianze,Huang, Hanmin
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supporting information
(2019/01/21)
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- Triple-Bond Insertion Triggers Highly Regioselective 1,4-Aminomethylamination of 1,3-Enynes with Aminals Enabled by Pd-Catalyzed C-N Bond Activation
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A highly chemo- and regioselective 1,4-aminomethylamination of simple enynes with aminals to allenic 1,5-diamines by taking advantage of C-N bond activation has been reported. The reaction proceeds under mild reaction conditions and can be performed under
- Zhang, Yanchen,Yu, Bangkui,Gao, Binjian,Zhang, Tianze,Huang, Hanmin
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supporting information
p. 535 - 539
(2019/01/24)
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- Allenoates in Enantioselective [2+2] Cycloadditions: From a Mechanistic Curiosity to a Stereospecific Transformation
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Identification of a novel catalyst-allenoate pair allows enantioselective [2+2] cycloaddition of α-methylstyrene. To understand the origin of selectivity, a detailed mechanistic investigation was conducted. Herein, two competing reaction pathways are proposed, which operate simultaneously and funnel the alkenes to the same axially chiral cyclobutanes. In agreement with the Woodward-Hoffmann rules, this mechanistic curiosity can be rationalized through a unique symmetry operation that was elucidated by deuteration experiments. In the case of 1,1-diarylalkenes, distal communication between the catalyst and alkene is achieved through subtle alteration of electronic properties and conformation. In this context, a Hammett study lends further credibility to a concerted mechanism. Thus, extended scope exploration, including β-substitution on the alkene to generate two adjacent stereocenters within the cyclobutane ring, is achieved in a highly stereospecific and enantioselective fashion (33 examples, up to >99:1 er).
- Wiest, Johannes. M.,Conner, Michael L.,Brown, M. Kevin
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supporting information
p. 15943 - 15949
(2018/11/23)
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- Asymmetric Intermolecular Heck Reaction of Propargylic Acetates and Cycloalkenes to Access Fused Cyclobutenes
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An asymmetric Heck annulation of propargylic acetates with several types of cyclic olefins affords highly strained cyclobutenes in high enantioselectivity.
- Jiao, Zhiwei,Shi, Qi,Zhou, Jianrong Steve
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supporting information
p. 14567 - 14571
(2017/10/23)
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- Radical Cyclizations for the Synthesis of Pyrroloindoles: Progress toward the Flinderoles
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Under the influence of Lewis acid catalysis, donor/acceptor cyclopropanes underwent nucleophilic ring opening by indolines. The resulting N-alkyl indolines bearing a pendant malonyl moiety oxidatively cyclized to 1,2-pyrroloindoles. This method was showcased by the preparation of the skeletal structure of the flinderoles.
- Tejeda, Joanne E. Curiel,Landschoot, Bryan K.,Kerr, Michael A.
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supporting information
p. 2142 - 2145
(2016/06/01)
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- SilverCatalyzed Cascade Carboxylation and Cyclization of Trimethyl(2-methylenebut-3-yn-1-yl)silane Derivatives
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C-C bond-forming carboxylation and cyclization of trimethyl(2-methylenebut-3-yn-1-yl)silane derivatives and carbon dioxide was developed. Silver catalysts and CsF promoted the reaction to afford the corresponding 2-furanone and 2-pyrone derivatives in goo
- Sekine, Kohei,Sadamitsu, Yuta,Yamada, Tohru
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p. 5706 - 5709
(2015/12/01)
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- Mn-Catalyzed Highly Efficient Aerobic Oxidative Hydroxyazidation of Olefins: A Direct Approach to β-Azido Alcohols
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(Chemical Equation Presented). An efficient Mn-catalyzed aerobic oxidative hydroxyazidation of olefins for synthesis of β-azido alcohols has been developed. The aerobic oxidative generation of azido radical employing air as the terminal oxidant is disclosed as the key process for this transformation. The reaction is appreciated by its broad substrate scope, inexpensive Mn-catalyst, high efficiency, easy operation under air, and mild conditions at room temperature. This chemistry provides a novel approach to high value-added β-azido alcohols, which are useful precursors of aziridines, β-amino alcohols, and other important N- and O-containing heterocyclic compounds. This chemistry also provides an unexpected approach to azido substituted cyclic peroxy alcohol esters. A DFT calculation indicates that Mn catalyst plays key dual roles as an efficient catalyst for the generation of azido radical and a stabilizer for peroxyl radical intermediate. Further calculation reasonably explains the proposed mechanism for the control of C-C bond cleavage or for the formation of β-azido alcohols.
- Sun, Xiang,Li, Xinyao,Song, Song,Zhu, Yuchao,Liang, Yu-Feng,Jiao, Ning
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supporting information
p. 6059 - 6066
(2015/05/27)
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- Templated carbene metathesis reactions from the modular assembly of enol-diazo compounds and propargyl acetates
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A Lewis acid mediated coupling reaction of enol-diazo nucleophiles and propargyl acetates has provided rapid and diverse access to complex alkynyl-tethered diazocarbonyl compounds. The ability of the coupling reaction to vary critical functionality flanking the diazo group was explored as a way to direct the outcome of a series of metal-catalyzed carbene metathesis cascade reactions. These cascade reactions provided diverse, biologically interesting carbocyclic and heterocyclic compounds in only a few steps from readily available materials. A general coupling strategy for the formation of alkynyl-substituted diazocarbonyl templates for catalytic cascade reactions is described. With the synthetic flexibility imparted to the coupling process and the facile cyclization of the first-formed metal carbene to secondary vinyl carbene templates, selective ylide, C-H insertion, and atom-transfer processes provide directed functionalization in cyclic compounds.
- Qian, Yu,Shanahan, Charles S.,Doyle, Michael P.
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p. 6032 - 6037
(2013/09/24)
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- The alkynyl moiety as a donor for donor-acceptor cyclopropanes
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The first trans-selective [3 + 2]-cycloaddition of a new type of donor-acceptor cyclopropane with aldehydes is presented. 2,2-Disubstituted cyclopropanes, bearing an alkyne moiety as the sole donor entity, were transformed to highly substituted tetrahydro
- Haubenreisser, Stefan,Hensenne, Peter,Schroeder, Sebastian,Niggemann, Meike
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supporting information
p. 2262 - 2265
(2013/06/27)
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- Copper-catalyzed regioselective reaction of internal alkynes and diaryliodonium salts
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The copper-catalyzed highly regioselective reaction of internal alkynes with diaryliodonium salts was achieved for the first time. α-Arylketones were obtained in moderate to good yields from arylpropargylic alcohols or aryl alkyl alkynes under mild condit
- Xu, Ze-Feng,Cai, Chen-Xin,Liu, Jin-Tao
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supporting information
p. 2096 - 2099
(2013/06/05)
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- Efficient and stereoselective nitration of mono- and disubstituted olefins with AgNO2 and TEMPO
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Nitroolefin is a common and versatile reagent. Its synthesis from olefin is generally limited by the formation of mixture of cis and trans compounds. Here we report that silver nitrite (AgNO2) along with TEMPO can promote the regio- and stereoselective nitration of a broad range of olefins. This work discloses a new and efficient approach wherein starting from olefin, nitroalkane radical formation and subsequent transformations lead to the desired nitroolefin in a stereoselective manner.
- Maity, Soham,Manna, Srimanta,Rana, Sujoy,Naveen, Togati,Mallick, Arijit,Maiti, Debabrata
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supporting information
p. 3355 - 3358
(2013/04/10)
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- Stereoselective synthesis of 1,3-dienes from propargylic alcohols by LiAlH4/AlCl3
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Herein we report that LiAlH4/AlCl3 is a very efficient reagent for the reductive dehydration of aryl propargylic alcohols in tetrahydrofuran solvent at reflux to give 1,3-dienes with good yields and high E selection. The reaction con
- Cui, Dong-Mei,Zhu, Kai,Chen, Li,Qi, Lang-Jun,Zhang, Cheng-Zhu,Zheng, Chen
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p. 2380 - 2384
(2013/07/26)
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- Multimetallic Ir-Sn3-catalyzed substitution reaction of π-activated alcohols with carbon and heteroatom nucleophiles
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An atom economic and catalytic substitution reaction of π-activated alcohols by a multimetallic IreSn3 complex has been demonstrated. The multimetallic IreSn3 complex can be easily synthesized from the reaction between [Cp*IrCl2]2 and SnCl2. In presence of as little as 1 mol % of the catalyst three different types of π-activated alcohols, namely benzyl, allyl, and propargyl alcohols, have been successfully transformed into alkylated products using carbon (arenes, heteroarenes, allyltrimethylsilane, and 1,3-dicarbonyls), nitrogen (sulfonamides), oxygen (alcohols), and sulfur (thiols) nucleophiles in very high yields. An electrophilic mechanism is proposed from the Hammett correlation study.
- Maity, Arnab Kumar,Chatterjee, Paresh Nath,Roy, Sujit
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p. 942 - 956
(2013/07/25)
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- Iron-catalyzed direct synthesis of densely Substituted benzofurans and naphthopyrans from phenolic compounds and propargylic alcohols
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A one-pot cascade reaction for the synthesis of polysubstituted benzofurans and naphthopyrans from simple phenols and propargylic alcohols catalyzed by iron(III) is presented. The results demonstrate that the structural specificity for the formation of fu
- Yuan, Feng-Quan,Han, Fu-She
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p. 537 - 547
(2013/05/08)
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- Expanding the scope of arylsulfonylacetylenes as alkynylating reagents and mechanistic insights in the formation of Csp2-Csp and Csp 3-Csp bonds from organolithiums
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We describe the unexpected behavior of the arylsulfonylacetylenes, which suffer an "anti-Michael" addition of organolithiums producing their alkynylation under very mild conditions. The broad scope, excellent yields, and simplicity of the experimental procedure are the main features of this methodology. A rational explanation of all these results can be achieved by theoretical calculations, which suggest that the association of the organolithiums to the electrophile is a previous step of their intramolecular attack and is responsible for the unexpected "anti-Michael" reactions observed for substituted sulfonylacetylenes. A calculated conclusion: A new transition-metal-free strategy for the synthesis of any kind of alkynyl derivatives in high yields in the reaction of organolithium species with arylsulfonylacetylenes is presented (see scheme). Theoretical calculations provide a rational explanation and suggest that association of the organolithium to the electrophile is a previous step of their intramolecular attack and is responsible for the "anti-Michael" reaction. Copyright
- Garcia Ruano, Jose Luis,Aleman, Jose,Marzo, Leyre,Alvarado, Cuauhtemoc,Tortosa, Mariola,Diaz-Tendero, Sergio,Fraile, Alberto
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supporting information; experimental part
p. 8414 - 8422
(2012/07/27)
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- Synthesis of 2,3-diiodoindenes and their applications in construction of 13H-indeno[1,2-l]phenanthrenes
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A series of 2,3-diiodoindene were synthesized at first, and 13H-indeno[1,2-l]phenanthrenes were then constructed via a Suzuki coupling reaction and subsequently a Scholl reaction. Structures of synthesized compounds were fully characterized by 1H NMR, 13C NMR, and HRMS. Their photophysical properties, such as UV-vis and FL spectra were investigated, and electronic properties were theoretically calculated by the software of Gaussian 03. The results suggested that these modified indene and indenophenanthrene compounds might have potential applications as light emitting materials.
- Zhou, Chao,Chen, Xiaopeng,Lu, Ping,Wang, Yanguang
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p. 2844 - 2850
(2012/05/05)
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- Highly chemoselective calcium-catalyzed propargylic deoxygenation
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A calcium-catalyzed direct reduction of propargylic alcohols and ethers has been accomplished by using triethylsilane as a nucleophilic hydride source. At room temperature a variety of secondary propargylic alcohols was deoxygenated to the corresponding h
- Meyer, Vera J.,Niggemann, Meike
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supporting information; experimental part
p. 4687 - 4691
(2012/05/04)
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- Heteropolyacid-catalyzed direct deoxygenation of propargyl and allyl alcohols
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The combination of H3[PW12O40] ?nH2O (1 mol %) and Et3SiH led to the direct catalytic deoxygenation of propargyl alcohols, in which proper solvent selection Cl(CH2)2Cl vs CF3CH2OH was the key to obtaining better product yields. Under similar conditions, the deoxygenation of allyl alcohols proceeded to give thermodynamically stable alkenes with migration of the double bonds in good yields.
- Egi, Masahiro,Kawai, Takuya,Umemura, Megumi,Akai, Shuji
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scheme or table
p. 7092 - 7097
(2012/10/07)
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- Beyond the limits: Palladium-N-heterocyclic carbene-based catalytic system enables highly efficient [4+2] benzannulation reactions
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A highly efficient catalytic system for the palladium-catalyzed [4+2] benzannulation reaction of enynes and enynophiles has been developed. The use of an N-heterocyclic carbene-based palladium precursor allowed us to achieve turnover numbers up to 1800. T
- Zatolochnaya, Olga V.,Galenko, Alexey V.,Gevorgyan, Vladimir
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supporting information; experimental part
p. 1149 - 1155
(2012/06/16)
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- Alkylation of 1,3-dicarbonyl compounds with benzylic and propargylic alcohols using Ir-Sn bimetallic catalyst: Synthesis of fully decorated furans and pyrroles
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The heterobimetallic complex [Ir(COD)(SnCl3)Cl(μ-Cl)] 2 catalyzes the direct substitution of hydroxyl groups in benzylic and propargylic alcohols by 1,3-dicarbonyl moiety. In 4-hydroxycoumarin, benzylation and propargylation occurs at the 3-position. Selective propargylation or allenylation takes place depending on the nature of propargylic alcohol. By applying the methodology, multi-substituted furans and pyrroles have been synthesized in good yields.
- Chatterjee, Paresh Nath,Roy, Sujit
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experimental part
p. 4569 - 4577
(2011/07/08)
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- First total synthesis of antrocamphin A and its analogs as anti-inflammatory and anti-platelet aggregation agents
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Naturally occurring antrocamphin A (1) is a potent anti-inflammatory compound from the edible fungus Antrodia camphorata (Taiwanofungus camphoratus), whose wild fruiting body is used as a valuable folk medicine in Taiwan. This study is the first total syn
- Lee, Chia-Lin,Huang, Chi-Huan,Wang, Hui-Chun,Chuang, Da-Wei,Wu, Ming-Jung,Wang, Sheng-Yang,Hwang, Tsong-Long,Wu, Chin-Chung,Chen, Yeh-Long,Chang, Fang-Rong,Wu, Yang-Chang
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supporting information; experimental part
p. 70 - 73
(2011/02/23)
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- Molecular sieves 5A as an acidic reagent: The discovery and applications
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The first use of molecular sieves (MS) 5A as an acidic reagent is described. We observed the acidic property during a dehydration reaction of 2-methyl-4-phenyl-3-butyn-2-ol. The acidity was sufficient to introduce ethoxyethyl and methoxyisopropyl protecting groups into alcohols. Additionally, the employment of MS 5A improved the synthesis of 1,2,4-orthoacetyl-α-d- glucopyranose at the intramolecular transorthoesterification step. In the other step of the synthesis, MS 4A was also applied to demonstrate that the manipulation of MS simplified the total operations.
- Asakura, Noriaki,Hirokane, Tsukasa,Hoshida, Hayato,Yamada, Hidetoshi
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scheme or table
p. 534 - 537
(2011/02/28)
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- Iron-catalyzed enyne cross-coupling reaction
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(Chemical Equation Presented) In the presence of 0.5-1 mol % of FeCl 3 with lithium bromide as a crucial additive, alkynyl Grignard reagents, prepared from the corresponding alkynes and methylmagnesium bromide, react with alkenyl bromides or triflates to give the corresponding conjugated enynes in high to excellent yields. The reaction shows wide applicability to various terminal alkynes and alkenyl electrophiles.
- Hatakeyama, Takuji,Yoshimoto, Yuya,Gabriel, Toma,Nakamura, Masaharu
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supporting information; experimental part
p. 5341 - 5344
(2009/06/06)
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- Efficient synthesis of enynes by tetraphosphine-palladium-catalysed reaction of vinyl bromides with terminal alkynes
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Through the use of [PdCl(C3H5)]2/cis,cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as catalyst, a range of vinyl bromides undergoes Sonogashira cross-coupling reaction with a variety of alkynes, leading to
- Feuerstein, Marie,Chahen, Ludovic,Doucet, Henri,Santelli, Maurice
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p. 112 - 120
(2007/10/03)
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- Ruthenium-catalyzed propargylic reduction of propargylic alcohols with silanes
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Ru2 can do it! Substitution of the OH moiety in propargylic alcohols by hydride proceeds smoothly with triethylsilane by catalysis with the thiolate-bridged diruthenium complex 1 (see scheme; Cp* = η5-C5Me5). Th
- Nishibayashi, Yoshiaki,Shinoda, Akira,Miyake, Yoshihiro,Matsuzawa, Hiroshi,Sato, Mitsunobu
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p. 4835 - 4839
(2007/10/03)
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- Propargylation of aromatic compounds with propargylic alcohols catalyzed by a cationic diruthenium complex
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Two metals are better than one: The cationic methanethiolate-bridged diruthenium complex 1 (Cp* = C5Me5, OTf = CF3SO3) promotes the catalytic propargylation of aromatic compounds with propargylic alcohols bearing not only terminal alkyne but also internal alkyne units, reactions that can not be carried out with some mononuclear catalysts. This reaction provides a general and environmentally friendly (atom economical, only H2O as byproduct) method for the synthesis of a variety of propargylated aromatic compounds.
- Nishibayashi, Yoshiaki,Inada, Youichi,Yoshikawa, Masato,Hidai, Masanobu,Uemura, Sakae
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p. 1495 - 1498
(2007/10/03)
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- Selective synthesis of conjugated enynes from α-arylalkynols using LiCl-Acidic Al2O3 under solvent-free conditions
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α-Arylalkynols were converted into conjugated enynes (in a selective manner under solvent-free conditions) using the LiCl-acidic Al2O3 couple as catalyst and support.
- Pourjavadi, Ali,Marandi, Gholam Bagheri
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p. 378 - 380
(2007/10/03)
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- Preparation of conjugated enynes and arylacetylenic compounds from arylalkynols using alumina in dry media
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Arylalkynols were converted into both conjugated enynes and arylacetylenic compounds using p-TsCl/Al2O3 and KOH/Al2O3 respectively in classical heating or microwave irradiation methods in good yields.
- Pourjavadi, Ali,Bagheri Marandi, Gholam
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p. 552 - 555
(2007/10/03)
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- Palladium-catalyzed arylation of enynes and electron-deficient alkynes using diaryliodonium salts
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matrix presentedA new single-pot procedure for the synthesis of aryl alkynes is described. Palladium catalyzes the coupling reaction of diaryliodonium compounds with enynes and electron-deficient alkynes to give aryl alkynes in good yields.
- Radhakrishnan, Ukkiramapandian,Stang, Peter J.
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p. 859 - 860
(2007/10/03)
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- Silacyclobutane compounds
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A silacyclobutane compound is disclosed having the formula: wherein R1and R2are independently chloro, triorganosiloxy, organooxy, triorganosilyl or a monovalent hydrocarbon group; R3is a monovalent hydrocarbon group free o
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- The palladium-catalyzed "vinylogous acetylenic Claisen rearrangement": a new vitamin A synthesis and a short path to allenic unsaturated carbonyls
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A new synthesis of retinal (vitamin A aldehyde) and various polyunsaturated carbonyls is proposed.Readily available mixed carbonates 1a-m are neatly transformed into 2a-m under the catalysis of palladium(0).In difficult cases (1a, 1b, 1m), ligand or catalyst tuning is effective for the regioisomeric control (2/3).Keywords: palladium / vinylogous Claisen rearrangement / retinal / vitamin A / allenes
- Bienayme, Hugues
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p. 696 - 708
(2007/10/02)
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- Electronic and Conformational Effects in the Photochemistry of α-Alkenyl-Substituted Vinyl Halides
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The photochemical reactions in methanol of the vinylic halides 2-halo-1-phenyl-1,3-butadienes 1-3Z-X (β-halo-β-alkenylstyrenes) and 1-halo-1,2-diphenylethenes 4Z-X (α-halostilbenes), with X = Cl or Br, have been studied quantitatively.E/Z isomerization, dehydrohalogenation, nucleophilic substitution, a -halogen shift, a -hydrogen shift, and oxidation are observed as the primary reactions.No reductive dehalogenation products are formed.The efficiencies of product formation are dependent on the halogen used, the electron-donating capacity of the α-substituent, the ground state conformation of the starting material, and the wavelength of excitation.Apart from the photoinduced E/Z isomerization and the oxidation reaction typical for alkenes, product formation occurs exclusively via vinyl-cationic intermediates, which are formed upon photolytic cleavage of the carbon-halogen bond.These ionic species, or part of them, are present as vinyl cation/halide anion-pairs.
- Krijnen, Erik S.,Zuilhof, Han,Lodder, Gerrit
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p. 8139 - 8150
(2007/10/02)
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- A new synthesis of polyunsaturated allenic carbonyls
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Palladium-catalysed transformation of readily available mixed carbonates 1a-l gives rise to a variety of allenic polyunsaturated aldehydes and ketones 2a-l. These carbonyls were sometimes contaminated with minor amounts of the undesired acetylenic regioisomers 3, and could be purified by silicagel chromatography.
- Bienayme, Hugues
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p. 7387 - 7390
(2007/10/02)
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- SYNTHESIS OF TRIFLUOROMETHYL- AND PENTAFLUOROPHENYLALKENYNES
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A four-stage method was developed for the production of conjugated trifluoromethyl- and pentafluorophenylalkenynes containing a perfluorinated substituent at the triple bond and also the structurally analogous hydrocarbons from the corresponding acetylenic compounds with protection of the triple bond by a dicobalt hexacarbonyl fragment.The method includes the production of trifluoromethyl- and pentafluorophenylalkynyl alcohols and their dicobalt hexacarbonyl complexes, dehydration of the latter, and oxidative demetallation of the obtained complexes of trifluoromethyl- and pentafluorophenylalkenynes by cerium ammonium nitrate.It was shown that trifluoromethylalkenynes can be synthesized by Pd(0)-catalyzed cross coupling of trifluoromethylethynylzinc and 2-iodopropene.
- Bobrovnikov, M. N.,Turbanova, E. S.,Petrov, A. A.
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p. 1445 - 1449
(2007/10/02)
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