- Enantioselective [3 + 2] annulation of 4-isothiocyanato pyrazolones and alkynyl ketones under organocatalysis
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An asymmetric [3 + 2] annulation reaction of 4-isothiocyanato pyrazolones with alkynyl ketones in the presence of an organic catalyst derived from a cinchona alkaloid under mild conditions is realized. This protocol provides unprecedented expeditious access to a wide range of optically active spiro[pyrroline-pyrazolones] with various electronic properties in high yields with good to excellent enantioselectivities.
- Wang, Wenyao,Wei, Shiqiang,Bao, Xiaoze,Nawaz, Shah,Qu, Jingping,Wang, Baomin
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p. 1145 - 1154
(2021/02/16)
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- Mono-Gold(I)-Catalyzed Enantioselective Intermolecular Reaction of Ynones with Styrenes: Tandem Diels–Alder and Ene Sequence
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Gold-catalyzed intermolecular reaction leading to dihydronaphthalene derivatives in one pot from two equivalents of ynones with respect to styrene is uncovered. The [4+2] Diels–Alder cycloaddition of ynones and styrenes is catalyzed by a mono-gold(I) complex and the conjugated acid to provide an unstable 3,8a-dihydronaphthalene to subsequently undergo an intermolecular ene-type reaction with the π-activated ynone to afford multi-component coupling dihydronaphthalene products. Linear relationships between chiral ligand-gold complexes and chiral dihydronaphthalene products proves mono-gold catalysis that triggers an asymmetric tandem Diels–Alder and ene reaction sequence.
- Nanko, Masaki,Inaba, Yuya,Sekine, Keisuke,Mikami, Koichi
-
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- Allenylidene Induced 1,2-Metalate Rearrangement of Indole-Boronates: Diastereoselective Access to Highly Substituted Indolines
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A process to achieve 1,2-metalate rearrangements of indole boronate as a way to access substituted indolines in high diastereoselectivities is presented. The reaction involves the generation of a Cu–allenylidene, which is sufficiently electrophilic to induce the 1,2-metalate rearrangement. The scope of the reaction is evaluated as well as further transformations of the product.
- Simlandy, Amit Kumar,Brown, M. Kevin
-
supporting information
p. 12366 - 12370
(2021/05/03)
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- Gold-Catalyzed Iminations of Terminal Propargyl Alcohols with Anthranils with Atypical Chemoselectivity for C(1)-Additions and 1,2-Carbon Migration
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This work reports gold-catalyzed iminations of terminal propargyl alcohols with anthranils or isoxazoles to yield E-configured α-amino-2-en-1-ones and -1-als with complete chemoselectivity. These catalytic iminations occur exclusively with C(1)-nucleophilic additions on terminal alkynes, in contrast to a typical C(2)-route. For 3,3-dialkylprop-1-yn-3-ols, a methyl substituent is superior to long alkyl chains as the 1,2-migration groups toward α-imino gold carbenes. For secondary prop-1-yn-3-ols, phenyl, vinyl, and cyclopropyl substituents are better than hydrogen as the migrating groups, obviating typical gold carbene reactions. DFT calculations have been performed to rationalize the observed C(1)-regioselectivity and the preferable cyclopropyl migration based on gold carbene pathways.
- Skaria, Manisha,More, Sayaji Arjun,Kuo, Tung-Chun,Cheng, Mu-Jeng,Liu, Rai-Shung
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supporting information
p. 3600 - 3608
(2020/03/04)
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- Allylic and Allenylic Dearomatization of Indoles Promoted by Graphene Oxide by Covalent Grafting Activation Mode
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The site-selective allylative and allenylative dearomatization of indoles with alcohols was performed under carbocatalytic regime in the presence of graphene oxide (GO, 10 wt percent loading) as the promoter. Metal-free conditions, absence of stoichiometric additive, environmentally friendly conditions (H2O/CH3CN, 55 °C, 6 h), broad substrate scope (33 examples, yield up to 92 percent) and excellent site- and stereoselectivity characterize the present methodology. Moreover, a covalent activation model exerted by GO functionalities was corroborated by spectroscopic, experimental and computational evidences. Recovering and regeneration of the GO catalyst through simple acidic treatment was also documented.
- Lombardi, Lorenzo,Bellini, Daniele,Bottoni, Andrea,Calvaresi, Matteo,Monari, Magda,Kovtun, Alessandro,Palermo, Vincenzo,Melucci, Manuela,Bandini, Marco
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supporting information
p. 10427 - 10432
(2020/07/24)
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- Cracking under internal pressure: Photodynamic behavior of vinyl azide crystals through N2release
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When exposed to UV light, single crystals of the vinyl azides 3- azido-1-phenylpropenone (1a), 3-azido-1-(4-methoxyphenyl)propenone (1b), and 3-azido-1-(4-chlorophenyl)propenone (1c) exhibit dramatic mechanical effects by cracking or bending with the release of N2. Mechanistic studies using laser flash photolysis, supported by quantum mechanical calculations, show that each of the vinyl azides degrades through a vinylnitrene intermediate. However, despite having very similar crystal packing motifs, the three compounds exhibit distinct photomechanical responses in bulk crystals. While the crystals of 1a delaminate and release gaseous N2 indiscriminately under paraffin oil, the crystals of 1b and 1c visibly expand, bend, and fracture, mainly along specific crystallographic faces, before releasing N2. The photochemical analysis suggests that the observed expansion is due to internal pressure exerted by the gaseous product in the crystal lattices of these materials. Lattice energy calculations, supported by nanoindentation experiments, show significant differences in the respective lattice energies. The calculations identify critical features in the crystal structures of 1b and 1c where elastic energy accumulates during gas release, which correspond to the direction of the observed cracks. This study highlights the hitherto untapped potential of photochemical gas release to elicit a photomechanical response and motility of photoreactive molecular crystals.
- Shields, Dylan J.,Karothu, Durga Prasad,Sambath, Karthik,Ranaweera, Ranaweera A. A. Upul,Schramm, Stefan,Duncan, Alexander,Duncan, Benjamin,Krause, Jeanette A.,Gudmundsdottir, Anna D.,Naumov, Pan?e
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p. 18565 - 18575
(2020/12/01)
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- Laccase-mediated Oxidations of Propargylic Alcohols. Application in the Deracemization of 1-arylprop-2-yn-1-ols in Combination with Alcohol Dehydrogenases
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The catalytic system composed by the laccase from Trametes versicolor and the oxy-radical TEMPO has been successfully applied in the sustainable oxidation of fourteen propargylic alcohols. The corresponding propargylic ketones were obtained in most cases in quantitative conversions (87–>99 % yield), demonstrating the efficiency of the chemoenzymatic methodology in comparison with traditional chemical oxidants, which usually lead to problems associated with the formation of by-products. Also, the stereoselective reduction of propargylic ketones was studied using alcohol dehydrogenases such as the one from Ralstonia species overexpressed in E. coli or the commercially available evo-1.1.200, allowing the access to both alcohol enantiomers mostly with complete conversions and variable selectivities depending on the aromatic pattern substitution (97–>99 % ee). To demonstrate the compatibility of the laccase-mediated oxidation and the alcohol dehydrogenase-catalyzed bioreduction, a deracemization strategy starting from the racemic compounds was developed through a sequential one-pot two-step process, obtaining a selection of (S)- or (R)-1-arylprop-2-yn-1-ols with excellent yields (>98 %) and selectivities (>98 % ee) depending on the alcohol dehydrogenase employed.
- González-Granda, Sergio,Méndez-Sánchez, Daniel,Lavandera, Iván,Gotor-Fernández, Vicente
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p. 520 - 527
(2019/11/16)
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- Relay Catalysis to Synthesize β-Substituted Enones: Organocatalytic Substitution of Vinylogous Esters and Amides with Organoboronates
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Organocatalysis was shown to facilitate conjugate additions to vinylogous esters and amides for the first time. Subsequent elimination of a β-alcohol or amine provided π-conjugated β-substituted enones. Remarkably, nucleophile addition to the electron-rich vinylogous substrates is more rapid than classical enones, forming monosubstituted products. A doubly organocatalytic (organic diol and methyl aniline) conjugate addition synthesized the products directly from alkynyl ketones. Both of these catalytic transformations are orthogonal to transition metal catalysis, allowing for good yields, easily accessible or commercially available reagents, high selectivity, reagent recovery and recyclability, facile scalability, and exceptional functional group tolerance.
- Sundstrom, Sasha,Nguyen, Thien S.,May, Jeremy A.
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supporting information
p. 1355 - 1359
(2020/02/13)
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- Arylboronic Acid Catalyzed C-Alkylation and Allylation Reactions Using Benzylic Alcohols
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The arylboronic acid catalyzed dehydrative C-alkylation of 1,3-diketones and 1,3-ketoesters using secondary benzylic alcohols as the electrophile is reported, forming new C-C bonds (19 examples, up to 98% yield) with the release of water as the only byproduct. The process is also applicable to the allylation of benzylic alcohols using allyltrimethylsilane as the nucleophile (12 examples, up to 96% yield).
- Estopi?á-Durán, Susana,McLean, Euan B.,Donnelly, Liam J.,Hockin, Bryony M.,Taylor, James E.
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supporting information
p. 7547 - 7551
(2020/10/09)
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- A sustainable access to ynones through laccase/TEMPO-catalyzed metal- and halogen-free aerobic oxidation of propargylic alcohols in aqueous medium
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Tuning laccase/TEMPO-catalyzed aerobic oxidation of secondary propargylic alcohols in aqueous media was accomplished in order to efficiently synthesize ynones. This study led to the formulation of an effective and sustainable catalytic method for the preparation of mono- and bis-substituted ynones compared with traditional oxidative methods.
- Silva, Alana B.V.,Silva, Emmanuel D.,dos Santos, Alcindo A.,Princival, Jefferson L.
-
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- Synthesis of (Z)-alkene-containing linear conjugated dienyl homoallylic alcohols by a palladium-catalyzed three-component reaction
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A synthesis of (Z)-alkene-containing linear conjugated dienyl homoallylic alcohols by using a palladium-catalyzed three-component reaction has been developed. This method shows good functional-group compatibility and generality, with high diastereoselectivity. Additionally, in many cases, the present method controls the alkene stereochemistry of the newly formed C-C bond and overcomes the inherent preference for (E)-alkene formation, giving (Z, E)- and (Z, Z)-products.
- Horino, Yoshikazu,Sakamoto, Juri,Murakami, Miki,Sugata, Miki
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supporting information
p. 1323 - 1327
(2020/08/21)
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- Covalent Adaptable Networks with Tunable Exchange Rates Based on Reversible Thiol–yne Cross-Linking
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The design of covalent adaptable networks (CANs) relies on the ability to trigger the rearrangement of bonds within a polymer network. Simple activated alkynes are now used as versatile reversible cross-linkers for thiols. The click-like thiol–yne cross-linking reaction readily enables network synthesis from polythiols through a double Michael addition with a reversible and tunable second addition step. The resulting thioacetal cross-linking moieties are robust but dynamic linkages. A series of different activated alkynes have been synthesized and systematically probed for their ability to produce dynamic thioacetal linkages, both in kinetic studies of small molecule models, as well as in stress relaxation and creep measurements on thiol–yne-based CANs. The results are further rationalized by DFT calculations, showing that the bond exchange rates can be significantly influenced by the choice of the activated alkyne cross-linker.
- Du Prez, Filip E.,Guerre, Marc,Maes, Diederick,Unal, Kamil,Van Herck, Niels,Winne, Johan M.
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supporting information
p. 3609 - 3617
(2020/02/04)
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- Iron (III)-Promoted Synthesis of Substituted 4H-Chalcogenochromenes and Chemoselective Functionalization
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The iron(III)-promoted synthesis of densely-substituted 4H-chalcogenchromene from organochalcogen propargylamines in the presence of diaryl dichalcogenides is reported. Subsequent C2-functionalization with electrophiles and potassium trifluoroborate salts
- de Oliveira, Isadora M.,Esteves, C. Henrique A.,Darbem, Mariana P.,Pimenta, Daniel C.,Zukerman-Schpector, Julio,Ferreira, Antonio G.,Stefani, Hélio A.,Manarin, Flavia
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supporting information
p. 3163 - 3172
(2019/05/10)
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- Neighboring Carbonyl Group Assisted Oxyacetoxylation of Propargylic Carboxylates with Retention of Chirality under Metal Free Condition
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A metal-free oxyacetoxylation method of primary, secondary and tertiary propargylic carboxylates with retention of chirality was presented. The reaction proceeds through the intramolecular nucleophilic attack of the neighboring carbonyl group on an alkynyliodonium intermediate. The process is general with broad substrate scope and is amenable for application to a variety of propargyl carboxylates including those obtained from natural products. Insight into the mechanistic pathway by isotopic labelling (using H2O18 and D2O) and controlled experiments confirmed. (Figure presented.).
- Pradhan, Tapas R.,Mohapatra, Debendra K.
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supporting information
p. 3605 - 3611
(2019/07/04)
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- Palladium-catalyzed [3+2] annulation of allenyl carbinol acetates with C,N-cyclic azomethine imines
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In this paper, a palladium-catalyzed [3+2] annulation of allenyl carbinol acetates with azomethine imines has successfully been developed under mild reaction conditions, affording biologically interesting tetrahydropyrazoloisoquinoline derivatives in high to excellent yields and with excellent stereoselectivity. The reaction follows a tandem [3+2] cycloaddition/allylation/elimination of AcOH pathway. Allenyl carbinol acetates also reacted well with in situ generated azomethine imine under cocatalysis of Ag(i)/Pd(0) catalysts in a similar reaction pathway.
- Mao, Biming,Zhang, Junya,Xu, Yi,Yan, Zhengyang,Wang, Wei,Wu, Yongjun,Sun, Changqing,Zheng, Bing,Guo, Hongchao
-
supporting information
p. 12841 - 12844
(2019/11/05)
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- Lipase/Oxovanadium Co-Catalyzed Dynamic Kinetic Resolution of Propargyl Alcohols: Competition between Racemization and Rearrangement
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Quantitative conversion of racemic propargyl alcohols into optically active propargyl esters with up to 99% ee has been achieved by lipase/oxovanadium co-catalyzed dynamic kinetic resolution, which combines the lipase-catalyzed enantioselective esterification of the racemic substrates and the in situ racemization of the remaining enantiomers. The success is owed to our discovery of a magic solvent, (trifluoromethyl)benzene, that accelerated the racemization while sufficiently suppressing the common oxovanadium-catalyzed rearrangement of propargyl alcohols to irreversibly produce enals.
- Kawanishi, Shinji,Oki, Shinya,Kundu, Dhiman,Akai, Shuji
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p. 2978 - 2982
(2019/03/26)
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- Trialkylborane-Mediated Multicomponent Reaction for the Diastereoselective Synthesis of Anti-δ,δ-Disubstituted Homoallylic Alcohols
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The trialkylborane/O2-mediated reaction of propargyl acetates having a tributylstannyl group at an alkyne terminus with aldehydes in a THF-H2O solvent system gave anti-δ,δ-disubstituted homoallylic alcohols with good to high diastereoselectivity. Intriguingly, two alkyl groups derived from trialkylborane were embedded into the reaction product. The trialkylborane plays a key role not only as a radical initiator but also as a source of alkyl radicals.
- Horino, Yoshikazu,Murakami, Miki,Aimono, Ataru,Lee, Jun Hee,Abe, Hitoshi
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supporting information
p. 476 - 480
(2019/01/14)
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- Trialkylborane-Mediated Propargylation of Aldehydes Using γ-Stannylated Propargyl Acetates
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A transition-metal-free three-component process that combines aldehydes, 3-(tributylstannyl)propargyl acetates formed in situ from readily available propargyl acetates, and trialkylboranes provides access to a range of 1,2,4-trisubstituted homopropargylic alcohols. The addition of diisopropylamine plays a crucial role in the selective formation of homopropargylic alcohols. Importantly, this methodology can be extended to a single-flask reaction sequence starting from propargyl acetates.
- Horino, Yoshikazu,Murakami, Miki,Ishibashi, Mayo,Lee, Jun Hee,Watanabe, Airi,Matsumoto, Rio,Abe, Hitoshi
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supporting information
p. 9564 - 9568
(2019/12/24)
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- Phosphorous acid promoted isomerization of propargyl alcohols to α,β-unsaturated carbonyl compounds
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A metal-free and two-phase protocol for the Meyer-Schuster isomerization of propargyl alcohols to the corresponding α,β-unsaturated carbonyl compounds has been achieved in the presence of stoichiometric phosphorous acid aqueous solution, which produces the desired products in high yields with excellent stereoselectivity. Compared with the traditional methods, the procedure features broad scope of the substrates, mild conditions, and easy separation, providing an appealing alternative to the Meyer-Schuster reaction.
- Gan, Xiaotang,Fu, Zuqi,Liu,Yan, Yani,Chen, Chao,Zhou, Yongbo,Dong, Jianyu
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supporting information
(2019/07/12)
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- A novel synthesis of N-hydroxy-3-aroylindoles and 3-aroylindoles
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A straightforward indole synthesis via annulation of C-nitrosoaromatics with conjugated terminal alkynones was realised achieving a simple, highly regioselective, atom- and step economical access to 3-aroylindoles in moderate to good yields. Further functionalizations of indole scaffolds were investigated and an easy way to JWH-018, a synthetic cannabinoid, was achieved.
- Ieronimo, Gabriella,Palmisano, Giovanni,Maspero, Angelo,Marzorati, Alessandro,Scapinello, Luca,Masciocchi, Norberto,Cravotto, Giancarlo,Barge, Alessandro,Simonetti, Marco,Ameta, Keshav Lalit,Nicholas, Kenneth M.,Penoni, Andrea
-
supporting information
p. 6853 - 6859
(2018/10/20)
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- Copper- and borinic acid-catalyzed propargylic etherification of propargylic carbonates with benzyl alcohols
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Propargylic substitution reactions have offered useful synthetic methods because further transformations based onthe alkyne moiety in the propargylic substituted products are readily achieved to construct more complex organic compounds. A large number of studies have been devoted to enantioselective propargylic substitution reactions with a variety of nucleophiles. However, successful examples of the use of alcohols as nucleophiles have been quite limited until now. To achieve utilization of aliphatic alcohols, herein we report the use of combined catalysis of a copper-pybox complex and a borinic acid. In this catalytic system, aliphatic alcohols such as benzyl alcohol derivatives were successfully applied to afford the corresponding propargylic etherified products in good yields with high enantioselectivities.
- Tsuchida, Kohei,Yuki, Masahiro,Nakajima, Kazunari,Nishibayashi, Yoshiaki
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supporting information
p. 671 - 673
(2018/04/30)
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- One-pot synthesis of polyfunctionalized quinolines: Via a copper-catalyzed tandem cyclization
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An efficient one-pot approach for the synthesis of polyfunctionalized quinolines was developed via a sequence of copper-catalyzed coupling reaction/propargyl-allenyl isomerization/aza-electrocyclization. Easily available starting materials, mild conditions, and a wide substrate scope make this approach potentially useful.
- Chen, Dianpeng,Sun, Xuejun,Shan, Yingying,You, Jinmao
-
supporting information
p. 7657 - 7662
(2018/11/02)
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- Gem-Digold Acetylide Complexes for Catalytic Intermolecular [4 + 2] Cycloaddition: Having Two Gold Centers Is Better for Asymmetric Catalysis
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Gold(I)-catalyzed highly enantioselective intermolecular [4 + 2] cycloaddition is shown with ynones and cyclohexadiene. Various bicyclo[2.2.2]octadiene derivatives are produced in high yields (up to 99%) with good enantioselectivity (up to 96% ee). Key to the success is generation of the gem-digold terminal alkyne as a catalytic on-cycle species. As proof of the gem-digold catalysis, a positive nonlinear effect is clarified between the ee's of the ligand and the cycloadduct.
- Nanko, Masaki,Shibuya, Satoru,Inaba, Yuya,Ono, Soichiro,Ito, Shigekazu,Mikami, Koichi
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supporting information
p. 7353 - 7357
(2018/10/15)
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- One-Pot, Three-Step Synthesis of Cyclopropylboronic Acid Pinacol Esters from Synthetically Tractable Propargylic Silyl Ethers
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Simple propargylic silyl ethers can be converted to complex cyclopropylboronic acid pinacol esters in an efficient one-pot procedure. Terminal acetylenes undergo a Schwartz's reagent catalyzed hydroboration; subsequent addition of further Schwartz's reage
- Spencer, Jonathan A.,Jamieson, Craig,Talbot, Eric P. A.
-
supporting information
p. 3891 - 3894
(2017/07/26)
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- Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols
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An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)2 or Cu(acac)2 and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as the reaction intermediate suggests that an insertion-elimination-type reaction, followed by borylcupration, is involved in the borylation of propargylic alcohols.
- Mao, Lujia,Bertermann, Rüdiger,Emmert, Katharina,Szabó, Kálmán J.,Marder, Todd B.
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supporting information
p. 6586 - 6589
(2017/12/26)
-
- 2,4,6-TRIALKOXYSTRYL ARYL SULFONES, SULFONAMIDES AND CARBOXAMIDES, AND METHODS OF PREPARATION AND USE
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Compounds according to Formula (I) are provided and salts thereof, wherein R1, R2, R33, R4, R5, R6, R13, A, X and Y are as defined herein. Methods for preparing compounds of Form
- -
-
Page/Page column 55; 56; 57
(2017/02/28)
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- Well-Defined Chiral Gold(III) Complex Catalyzed Direct Enantioconvergent Kinetic Resolution of 1,5-Enynes
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The development of a gold(III) catalyzed direct enantioconvergent 1,5-enyne cycloisomerization and kinetic resolution reaction is described. The transformation results in highly enantioenriched bicyclo[3.1.0]hexenes at all levels of conversion, with no racemization or symmetrization taking place during the course of the reaction, and simultaneously affords optically enriched 1,5-enynes. This report marks the first highly enantioselective transformation catalyzed by a well-defined cationic gold(III) catalyst and demonstrates the unique potential of gold(III) complexes in enantioselective catalysis.
- Bohan, Patrick T.,Dean Toste
-
supporting information
p. 11016 - 11019
(2017/08/22)
-
- Synthesis and cytotoxicity evaluation of aryl triazolic derivatives and their hydroxymethine homologues against B16 melanoma cell line
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In this manuscript we describe synthesis and cytotoxicity evaluation of some triazolic derivatives against B16 melanoma cell line. For this purpose, we transformed a set of aromatic aldehydes into terminal alkynes, using Besthmann-Ohira reagent, and we made the corresponding hydroxymethyl homologated alkynes by an acetylene Grignard reagent. These generated two sets of alkynes were then subjected to a copper(I)-catalyzed alkyne-azide cycloaddition reaction (CuAAC) using a solid-supported catalyst (Amberlyst A-21?CuI), with a third set composed of organic azides. Synthesized triazoles were then tested in?vitro against B16 melanoma cell line. Amongst them, compounds a1b1 (R1?=?p-nitrophenyl, R2?=?benzyl), a4b1 (R1?=?naphthyl, R2?=?benzyl) and a4b5 (R1?=?naphthyl, R2?=?(R/S)- dioxolane) showed the best activity against B16 melanoma cells, with IC50of 5.12, 3.89 and 6.60?μM respectively.
- Kalhor-Monfared, Shiva,Beauvineau, Claire,Scherman, Daniel,Girard, Christian
-
supporting information
p. 436 - 441
(2016/07/15)
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- Highly stereoselective kinetic resolution of α-allenic alcohols: An enzymatic approach
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A highly efficient lipase AK-catalyzed direct kinetic resolution of a variety of α-allenic alcohols was developed. With the complementary to previous studies, the current reaction system is effective on a broad range of substituents (R1) at C(1), such as alkyl, aryl, alkenyl, and alkynyl groups. The Jones-Burgess empirical model was modified to interpret the reversed selectivity during the acetylation of secondary alcohol. The methyl group at C(2) of allenic alcohols implied a small structural adjustment in the catalytic triad of lipase AK, representing a potential direction for future site-directed mutagenesis.
- Li, Wenhua,Lin, Zuming,Chen, Long,Tian, Xuechao,Wang, Yan,Huang, Sha-Hua,Hong, Ran
-
supporting information
p. 603 - 606
(2016/01/20)
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- Cu-Pybox catalyzed synthesis of 2,3-disubstituted imidazo[1,2-a]pyridines from 2-aminopyridines and propargyl alcohol derivatives
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A highly efficient cascade sequence for syntheses of 2,3-disubstituted imidazo[1,2-a]pyridines with exclusive regioselectivity in moderate to excellent yields has been developed. This cascade was initiated through propargylation of 2-aminopyridines at pyridine-nitrogen with propargyl alcohol derivatives using Cu(II)-Pybox as catalyst and followed by an intramolecular cyclization and isomerization. Besides 2-aminopyridine, less reactive 2-aminopyrimidine, 2-aminopyrazine and 3-aminopyridazine were also suitable in this cascade.
- Cheng, Cang,Ge, Luo,Lu, Xuehe,Huang, Jianping,Huang, Haocheng,Chen, Jie,Cao, Weiguo,Wu, Xiaoyu
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p. 6866 - 6874
(2016/10/04)
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- Styrene as 4π-Component in Zn(II)-Catalyzed Intermolecular Diels-Alder/Ene Tandem Reaction
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A mild Zn-catalyzed intermolecular Diels-Alder/ene tandem reaction with styrene as a 4π-component is reported. A variety of dihydronaphthalene products could be prepared in moderate to good yields. Moreover, a combination of DFT calculations and experiments was performed to further understand the mechanism of this unique tandem reaction.
- Zheng, Min,Wu, Feng,Chen, Kai,Zhu, Shifa
-
supporting information
p. 3554 - 3557
(2016/08/16)
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- Flash chemistry using trichlorovinyllithium: Switching the reaction pathways by high-resolution reaction time control
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High-resolution reaction time control in flow microreactors enables the reaction-pathway switching of trichlorovinyllithium generated by the H/Li exchange of trichloroethene. The method was successfully app lied to the synthesis of 1,1,2-trichloroalkenes,
- Nagaki, Aiichiro,Takahashi, Yusuke,Henseler, Andrea,Matsuo, Chika,Yoshida, Jun-Ichi
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supporting information
p. 214 - 216
(2015/03/05)
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- Trialkyl Methanetricarboxylate as Dialkyl Malonate Surrogate in Copper-Catalyzed Enantioselective Propargylic Substitution
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The first copper-catalyzed enantioselective propargylation of trialkyl methantricarboxylate with propargylic alcohol derivatives was developed. The tricarboxylate unit in the obtained adducts could be easily transformed into a malonate moiety by treating with in situ generated NaOEt in excellent yield without racemization.
- Huang, Guanxin,Cheng, Cang,Ge, Luo,Guo, Beibei,Zhao, Long,Wu, Xiaoyu
-
supporting information
p. 4894 - 4897
(2015/10/12)
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- HBF4-Catalysed Nucleophilic Substitutions of Propargylic Alcohols
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The activity of HBF4 (aqueous solution) as a catalyst in propargylation reactions is presented. Diverse types of nucleophiles were employed in order to form new C-O, C-N and C-C bonds in technical acetone and in air. Good to excellent yields and good chemoselectivities were obtained using low acid loading (typically 1 mol-%) under simple reaction conditions. The activity of HBF4 (aq. solution) as a catalyst in propargylation reactions is presented. C-O, C-N and C-C bonds were formed in technical acetone and in air. Good to excellent yields were obtained using low acid loading (typically 1 mol-%) under mild reaction conditions.
- Barreiro, Elena,Sanz-Vidal, Alvaro,Tan, Eric,Lau, Shing-Hing,Sheppard, Tom D.,Dez-Gonzlez, Silvia
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supporting information
p. 7544 - 7549
(2016/01/26)
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- Synthesis of highly substituted γ-butyrolactones by a gold-catalyzed cascade reaction of benzyl esters
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Easily accessible benzylic esters of 3-butynoic acids in a gold-catalyzed cyclization/rearrangement cascade reaction provided 3-propargyl γ-butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new C-C bond is an intermolecular process. Initially propargylic-benzylic esters were used, but alkyl-substituted benzylic esters worked equally well. In the case of the propargylic- benzylic products, a simple treatment of the products with aluminum oxide initiated a twofold tautomerization to the allenyl-substituted g-butyrolactones with conjugation of the carbonyl group, the olefin, and the allene. The synthetic sequence can be conducted stepwise or as a one-pot cascade reaction with similar yields. Even in the presence of the gold catalyst the new allene remains intact.
- Jaimes, Maria Camila Blanco,Ahrens, Alexander,Pfl?sterer, Daniel,Rudolph, Matthias,Hashmi, A. Stephen K.
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supporting information
p. 427 - 433
(2015/02/18)
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- Silver-Catalyzed Cyclization of Propargylic Amides to Oxazolines
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A ligand-accelerated effect is observed in the cyclization of propargylic amides catalyzed by bis(pyridyl)silver(I) complexes, with an unexpected reversal of electronic demand to the analogous NH addition reaction. The catalyst was found to be effective for internal alkyne substrates, offering exclusive selectivity for the 5-exo-dig product. Differences in selectivity profile between gold- and silver-catalyzed processes are highlighted and discussed.
- Wong, Valerie H. L.,White, Andrew J. P.,Hor,Hii
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supporting information
p. 3943 - 3948
(2016/01/25)
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- Convenient and highly efficient routes to 2 H-chromene and 4-chromanone derivatives: Iodine-promoted and p-toluenesulfonic acid catalyzed cascade cyclizations of propynols
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A convenient strategy is presented for the easy preparation of a series of 2 H-chromenes under mild conditions through iodocyclization of readily accessible propynols. In addition, various 4-chromanones can be synthesized through a p-toluenesulfonic acid catalyzed cascade cyclization with high efficiency (yields up to 99%). Our developed reaction systems are proven to have good functional-group applicability and can be scaled up to gram quantities in satisfactory yields. These systems also provide a new synthetic strategy for two types of important flavonoid skeleton without using costly and toxic metal catalysts. Additionally, the resulting halides could be further exploited in subsequent palladium-catalyzed coupling reactions, so these compounds could act as potential intermediates for the construction of some valuable drug molecules.
- Qiu, Yi-Feng,Ye, Yu-Ying,Song, Xian-Rong,Zhu, Xin-Yu,Yang, Fang,Song, Bo,Wang, Jia,Hua, Hui-Liang,He, Yu-Tao,Han, Ya-Ping,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 3480 - 3487
(2015/03/04)
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- Cooperative catalysis: Enantioselective propargylic alkylation of propargylic alcohols with enecarbamates using ruthenium/Phosphoramide hybrid catalysts
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The diastereo- and enantioselective propargylic alkylation of propargylic alcohols with E-enecarbamates in the presence of a catalytic amount of thiolate-bridged diruthenium complexes bearing an optically active phosphoramide moiety gives the corresponding propargylic alkylated products (up to 97 % ee).
- Senda, Yasushi,Nakajima, Kazunari,Nishibayashi, Yoshiaki
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supporting information
p. 4060 - 4064
(2015/03/30)
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- Synthesis and evaluation of novel fluorinated pyrazolo-1,2,3-triazole hybrids as antimycobacterial agents
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A library of novel 3-trifluoromethyl pyrazolo-1,2,3-triazole hybrids (5-7) were accomplished starting from 5-phenyl-3-(trifluoromethyl)-1H-pyrazol-4-amine (1) via key intermediate 2-azido-N-(5-phenyl-3-(trifluoromethyl)-1H-pyrazol-4-yl)acetamide (3) throu
- Emmadi, Narender Reddy,Bingi, Chiranjeevi,Kotapalli, Sudha Sravanti,Ummanni, Ramesh,Nanubolu, Jagadeesh Babu,Atmakur, Krishnaiah
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supporting information
p. 2918 - 2922
(2015/06/22)
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- Synthesis of β-Trifluoromethylated Ketones from Propargylic Alcohols by Visible Light Photoredox Catalysis
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Regioselective trifluoromethylation at a remote position represents an important challenge in the development of biologically active molecules and functional materials. A practical method to access β-trifluoromethyl ketones from readily available propargylic alcohols by visible light photocatalysis has been developed. Trifluoromethylation of propargylic alcohols with CF3I in the presence of Ru(bpy)3Cl2 as the photocatalyst followed by double-bond migration/keto-enol tautomerization provides β-trifluoromethyl ketones as the final product. β-Trifluoromethyl ketones are synthesized from readily available propargylic alcohols by visible light photocatalysis. Trifluoromethylation followed by double-bond migration/keto-enol tautomerization provides β-trifluoromethyl ketones as the final product.
- Park, Sehyun,Joo, Jung Min,Cho, Eun Jin
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supporting information
p. 4093 - 4097
(2015/07/01)
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- Gold-catalyzed reactions of propargylic esters with vinylazides for the synthesis of Z- or E-configured buta-1,3-dien-2-yl esters
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Gold-catalyzed synthesis of buta-1,3-dien-2-yl esters by the reaction of propargyl esters with vinylazides is described; the reaction mechanism is postulated to involve a vinyl attack of vinylazides at alkenyl gold carbenes.
- Wagh, Sachin Bhausaheb,Liu, Rai-Shung
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supporting information
p. 15462 - 15464
(2015/10/20)
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- Stereoselective, Cascade Synthesis of trans-Enynones through Coupling-Isomerization Reaction
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A mild, cascade methodology based on the modified Cadiot-Chodkiewicz reaction was developed for the stereoselective synthesis of trans-enynones. By this methodology, structurally divergent trans-enynones, which are embedded with sensitive functional groups, were synthesized. Control experiments suggested that the CuCl alone does not have a role in the isomerization step, whereas the CuCl-piperidine complex (formed during the cross coupling) may have a rate enhancing effect. Furthermore, additional sets of control experiments favor the involvement of unimolecular [1,2]-H shift rather than a homobimolecular proton abstraction during the isomerization step.
- Chinta, Bhavani Shankar,Baire, Beeraiah
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p. 10208 - 10217
(2015/11/03)
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- Intramolecular halogen bonding supported by an aryldiyne linker
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Intramolecular halogen bonds between aryl halide donors and suitable acceptors, such as carbonyl or quinolinyl groups, held in proximity by 1,2-aryldiyne linkers, provide triangular structures in the solid state. Aryldiyne linkers provide a nearly ideal t
- Widner, Danielle L.,Knauf, Qianwei R.,Merucci, Mark T.,Fritz, Thomas R.,Sauer, Jon S.,Speetzen, Erin D.,Bosch, Eric,Bowling, Nathan P.
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p. 6269 - 6278
(2014/07/21)
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- Br?nsted acid-catalyzed meyer-schuster rearrangement for the synthesis of α, β -unsaturated carbonyl compounds
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An efficient and simple protocol for the Meyer-Schuster rearrangement of propargyl alcohols into α,β-unsaturated carbonyl compounds has been developed using catalytic amounts of p-toluenesulfonic acid in 1,2-dichloroethane.
- Park, Jungmin,Yun, Jihee,Kim, Jaehyun,Jang, Dong-Jin,Park, Cheol Ho,Lee, Kooyeon
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supporting information
p. 1924 - 1929
(2014/07/07)
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- Gold(I)-catalysed tandem cyclisation of propargyl acetals and vinyl esters
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The results of our previous comparative study of chemoselective gold(I)-catalysed alkene cycloadditions of propargyl substrates demonstrated that propargyl acetals react by different cyclisation pathways from the corresponding esters, and that they also have significantly higher reactivities. To increase understanding of the chemistry of propargyl acetals and to explore the possibilities of generating new compounds through gold(I)-catalysed reactions, a range of reactions of propargyl acetals with vinyl esters have been carried out. A new type of cyclopropyl-cyclopentenyl products, (1,3-dimethoxy-4,5-diphenylcyclopent-2-en-1-yl)-cyclopropyl ester derivatives, was obtained. A plausible mechanism, including sequential [1+2] and [2+3] cycloadditions, is proposed for these highly regio- and stereoselective gold(I)-catalysed reactions. The cyclopentenylation took place stereoselectively, whereas cis/trans mixtures of diastereoisomers were formed in the cyclopropanation step, with the selectivity being controlled by the bulkier vinylic substituent. The tandem reaction allows the construction of polysubstituted and highly functionalised bicyclic compounds. Copyright
- Siah, Huey-San Melanie,Kaur, Maya,Iqbal, Naseem,Fiksdahl, Anne
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p. 1727 - 1740
(2014/03/21)
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- Gold(I)-Catalysed Tandem Cyclisation of Propargyl Acetals and Vinyl Esters
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The results of our previous comparative study of chemoselective gold(I)-catalysed alkene cycloadditions of propargyl substrates demonstrated that propargyl acetals react by different cyclisation pathways from the corresponding esters, and that they also have significantly higher reactivities. To increase understanding of the chemistry of propargyl acetals and to explore the possibilities of generating new compounds through gold(I)-catalysed reactions, a range of reactions of propargyl acetals with vinyl esters have been carried out. A new type of cyclopropyl-cyclopentenyl products, (1,3-dimethoxy-4,5-diphenylcyclopent-2-en-1-yl)-cyclopropyl ester derivatives, was obtained. A plausible mechanism, including sequential [1+2] and [2+3] cycloadditions, is proposed for these highly regio- and stereoselective gold(I)-catalysed reactions. The cyclopentenylation took place stereoselectively, whereas cis/trans mixtures of diastereoisomers were formed in the cyclopropanation step, with the selectivity being controlled by the bulkier vinylic substituent. The tandem reaction allows the construction of polysubstituted and highly functionalised bicyclic compounds.
- Siah, Huey-San Melanie,Kaur, Maya,Iqbal, Naseem,Fiksdahl, Anne
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p. 1727 - 1740
(2015/10/05)
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- Bronsted acid mediated nitrogenation of propargylic alcohols: An efficient approach to alkenyl nitriles
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A novel and efficient approach to alkenyl nitriles from readily available propargylic alcohols has been developed. This nitrogenation reaction is transition-metal-free and could be conducted under air at ambient temperature, which makes this protocol promising and practical. Moreover, NH4Br is disclosed as an efficient additive to promote the stereoselectivity of this reaction. the Partner Organisations 2014.
- Huang, Xiaoqiang,Jiao, Ning
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supporting information
p. 4324 - 4328
(2014/06/23)
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- Diastereo- and enantioselective propargylation of benzofuranones catalyzed by pybox-copper complex
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Diastereo- and enantioselective preparation of 2,2-disubstituted benzofuran-3(2H)-one has been realized by a pybox-copper catalyzed reaction between 2-substituted benzofuran-3(2H)-one and propargyl acetate. The utility of this method was demonstrated by further transformation of the terminal alkyne into a methyl ketone without loss of enantiomeric purity.
- Zhao, Long,Huang, Guanxin,Guo, Beibei,Xu, Lijun,Chen, Jie,Cao, Weiguo,Zhao, Gang,Wu, Xiaoyu
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supporting information
p. 5584 - 5587
(2015/02/19)
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- Direct synthesis of pyrroles via 1,3-dipolar cycloaddition of azomethine ylides with ynones
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A direct and facile synthesis of multi-substituted pyrroles via AgOAc-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with ynones is developed, providing the corresponding adducts in moderate to high yields (up to 89%).
- Wang, Zheng,Shi, Ying,Luo, Xiaoyan,Han, De-Man,Deng, Wei-Ping
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supporting information
p. 1742 - 1745
(2013/06/27)
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- Parallel synthesis of "Click" chalcones as antitubulin agents
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It has been shown that some chalcones are able to inhibit tubulin polymerization, giving cytotoxicity and destruction of tumoral vasculature. A library of 180 novel chalcone analogs has been synthesized via click chemistry and screened for their cytotoxic
- Utsintong, Maleeruk,Massarotti, Alberto,Caldarelli, Antonio,Theeramunkong, Sewan
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p. 510 - 516
(2013/07/28)
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