- Molecular Solar Thermal Batteries through Combination of Magnetic Nanoparticle Catalysts and Tailored Norbornadiene Photoswitches
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Cobalt catalysts are immobilized on the surface of iron oxide nanoparticles for the preparation of highly active quasi-homogeneous catalysts toward an efficient release of photochemically stored energy in norbornadiene-based photoswitches. The facile sepa
- Lorenz, Patrick,Luchs, Tobias,Hirsch, Andreas
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supporting information
p. 4993 - 5002
(2021/02/26)
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- Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
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The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
- Liu, En-Chih,Topczewski, Joseph J.
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supporting information
p. 5308 - 5313
(2021/05/04)
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- Selective synthesis of trisubstituted pyrroles through the reactions of alkynyl Fischer carbene complexes with oxazolones
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An efficient and simple synthesis of novel trisubstituted 1H-pyrroles 4a-qvia 1,3-dipolar cycloaddition of Δ3-trifluoromethyloxazolones 2a-d with both chromium and tungsten alkynyl Fischer carbene complexes (1a-h) is described. An unexpected and unreported -CF3 group elimination process was observed in the pyrrole structure. Our experimental and theoretical data suggested that the metal fragment may be responsible for this phenomenon. The dipolar cycloaddition proceeded efficiently to produce a single regioisomer, which was unambiguously established through NMR and single-crystal X-ray diffraction studies. Nevertheless, the reaction of alkynyl carbenes bearing an α,β,γ,δ-unsaturated moiety with excess oxazolone 2a produced a polycyclic compound 6 speculatively formed through a cascade reaction involving 1,6-, 1,4- and 1,2-nucleophilic addition steps.
- López, Julio,Velazco-Cabral, Iván,Rodríguez-DeLeón, Eloy,Villegas Gómez, Clarisa,Delgado, Francisco,Tamariz, Joaquín,Arrieta, Ana,Cossío, Fernando P.,Vázquez, Miguel A.
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supporting information
p. 538 - 550
(2020/01/30)
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- Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands
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A chiral phenol–NHC ligand enabled the copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters. The phenol moiety of the chiral NHC ligand played a critical role in producing the enantiomerically enriched products. The catalyst worked well for various (Z)-isomer substrates. Opposite enantiomers were obtained from (Z)- and (E)-isomers, with a higher enantiomeric excess from the (Z)-isomer.
- Mimura, Shohei,Mizushima, Sho,Sawamura, Masaya,Shimizu, Yohei
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p. 537 - 543
(2020/05/14)
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- Gold-catalyzed partial hydrogenation of activated alkynes mediated by triphenylphosphine
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Gold(I) can exhibit a cooperative effect with triphenylphosphine, accelerating the triphenylphosphine-mediated partial hydrogenation of activated alkynes. In this protocol, 3-arylpropiolates are selectively reduced to the Z -isomer when the aryl ring bears an electron-donor substituent, whereas 3-arylpropynones are reduced to the E-isomers.
- Cocoletzi-Xochitiotzi, Ana Patricia,Hernández-Hernández, Miguel,Medina-Mercado, Ignacio,Jiménez-Martínez, Williams De Jesús,Mastranzo, Virginia Maricela,Porcel, Susana
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supporting information
p. 2379 - 2386
(2020/08/19)
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- Consecutive Three-Component Coupling-Addition Synthesis of β-Amino Enoates and 3-Hydroxypyrazoles via Ethyl 3-Arylpropiolates
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Two consecutive three-component syntheses furnishing β-amino enoates or 3-hydroxypyrazoles based upon the Sonogashira alkynylation of aryl iodides and ethyl propiolate were established in mostly excellent yields. The ethyl 3-arylpropiolate intermediates are Michael systems which are suited for concatenation with conjugate addition or cyclocondensation giving access to libraries of 21 different β-amino enoates and 17 different 3-hydroxypyrazoles. The rotational barrier of β-pyrrolidino enoates was assessed by studying the coalescence of pyrrolidinyl protons in VT-NMR spectra of electronically different substituted derivatives showing that the electronic substituent effect on the aryl group does not affect the height of the rotational barrier. This indicates that the substituents are essentially oriented orthogonally to the plane of the β-pyrrolidino enoates.
- Niedballa, Jonas,Reiss, Guido J.,Müller, Thomas J. J.
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supporting information
p. 5019 - 5024
(2020/07/24)
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- A Parallel Approach to 7-(Hetero)arylpyrazolo[1,5- a]pyrimidin-5-ones
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A modular, two-pot assembly of 7-arylpyrazolo[1,5-a]pyrimidones from aryl/heteroaryl halides and aminopyrazoles in library format was developed. Sonogashira coupling of aryl bromides with triethyl orthopropiolate, followed by in situ orthoester hydrolysis
- Schmitt, Daniel C.,Niljianskul, Nootaree,Sach, Neal W.,Trujillo, John I.
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p. 256 - 260
(2018/05/24)
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- Rhodium-catalyzed enantioselective decarboxylative alkynylation of allenes with arylpropiolic acids
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A rhodium-catalyzed chemo-, regio-, and enantioselective intermolecular decarboxylative alkynylation of terminal allenes with arylpropiolic acids is reported. Employing a Rh(I)/(R)-Tol-BINAP catalytic system, branched allylic 1,4-enynes were obtained under mild conditions. The overall utility of this protocol is exemplified by a broad functional group compatibility.
- Grugel, Christian P.,Breit, Bernhard
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p. 1066 - 1069
(2018/02/23)
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- Phosphine-mediated partial reduction of alkynes to form both (E)- and (Z)-alkenes
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A mild, phosphine-mediated partial reduction of alkynyl carbonyls to the corresponding alkenes was developed. Tuning of the reaction conditions led to either the (E)- or (Z)-diastereomer with high selectivity. A range of alkynyl esters, amides, and ketones were reduced to form alkenes in good to high yields and with excellent functional group tolerance.
- Pierce, Brett M.,Simpson, Brittany F.,Ferguson, Kane H.,Whittaker, Rachel E.
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supporting information
p. 6659 - 6662
(2018/09/29)
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- Understanding the mechanism of transition metal-free: Anti addition to alkynes: The selenoboration case
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The stereoselective anti-addition of selenoboranes to α,β-acetylenic esters and amides was achieved in a transition metal-free context using catalytic amounts of PCy3. The reaction provides anti-3,4-selenoboration with concomitant delivery of α-vinyl selenides by protodeboronation with MeOH. Interestingly, in the absence of phosphine the selenoboration switches towards the formation of β-vinyl selenides. Theoretical calculations rationalize the regio- and stereoselectivity of the reaction by discovering a new mechanism for the anti-3,4-selenoboration. While the selenoborane is activated via the "push-pull" effect of B, the phosphine interacts with the β position of the alkynoate switching the polarity of the triple bond and favoring 1,3-selenoboration which provides the α-addition of the selenyl group. Then, the autocatalytic action of a second selenoborane reagent, which coordinates to the phosphorus ylide intermediate, determines the stereoselectivity and completes the catalytic process. Finally, the comparison of selenoborane reagents with diboranes and silaboranes, which have exhibited analogous reactivity, shows that the selenium moiety has a larger nucleophilic character favoring the performance of the reaction under mild conditions.
- García-López, Diego,Civit, Marc G.,Vogels, Christopher M.,Ricart, Josep M.,Westcott, Stephen A.,Fernández, Elena,Carbó, Jorge J.
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p. 3617 - 3628
(2018/07/29)
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- Triazole-imidazole (TA-IM) derivatives as ultrafast fluorescent probes for selective Ag+ detection
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1,2,3-Triazole-imidazole derivatives (TA-IM) were prepared as fluorescent probes for silver ion detection. The design principle is the incorporation of an intramolecular H-bond between the imidazole and triazole moiety that enables a co-planar conformation to achieve fluorescence emission in the UV-blue range. Screening of different metal ions revealed excellent binding affinity of this new class of compounds toward silver ions in aqueous solution. The novel probe provided ultrafast detection (30 s) even for a very low concentration of silver ions (in the nM range) with good linear correlation, making it a practical sensor for detection of silver ions.
- Lai, Qi,Liu, Qing,He, Ying,Zhao, Kai,Wei, Chiyu,Wojtas, Lukasz,Shi, Xiaodong,Song, Zhiguang
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supporting information
p. 7801 - 7805
(2018/11/21)
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- Rhodium(III)-Catalyzed Redox-Neutral Cascade [3 + 2] Annulation of N-Phenoxyacetamides with Propiolates via C-H Functionalization/Isomerization/Lactonization
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A Rh(III)-catalyzed cascade [3 + 2] annulation of N-phenoxyacetamides with propiolates under mild conditions using the internal oxidative O-N bond as the directing group has been achieved. This catalytic system provides a regio- and stereoselective access to benzofuran-2(3H)-ones bearing exocyclic enamino motifs with exclusive Z configuration selectivity, acceptable to good yields and good functional group compatibility. Mechanistic investigations by experimental and density functional theory studies suggest that a consecutive process of C-H functionalization/isomerization/lactonization is likely to be involved in the reaction.
- Pan, Jin-Long,Chen, Chao,Hao, Yu,Liu, Chang,Bai, He-Yuan,Ding, Jun,Zhang, Shu-Yu,Wang, Li-Ren,Xie, Peipei,Xia, Yuanzhi
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supporting information
p. 7131 - 7136
(2018/12/14)
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- A Robust and Broadly Applicable Cobalt-Catalyzed Cross-Coupling of Functionalized Bench-Stable Organozinc Pivalates with Unsaturated Halides
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We report a robust and broadly applicable CoCl2-catalyzed cross-coupling between functionalized aryl and heteroaryl zinc pivalates and various electron-poor aryl and heteroaryl halides (X=Cl, Br, I). Couplings with (E)- or (Z)-bromo- or iodo-alkenes proceed with retention of configuration. Also, alkynyl bromides react with arylzinc pivalates providing arylated alkynes.
- Hammann, Jeffrey M.,Lutter, Ferdinand H.,Haas, Diana,Knochel, Paul
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supporting information
p. 1082 - 1086
(2017/01/18)
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- Development of Gold-catalyzed [4+1] and [2+2+1]/[4+2] Annulations between Propiolate Derivatives and Isoxazoles
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Two new gold-catalyzed annulations of isoxazoles with propiolates have been developed. Most isoxazoles follow an initial O attack on the alkyne to afford a [4+1] annulation product. This process results in a remarkable alkyne cleavage of initial propiolates. Unsubstituted isoxazoles proceed through an N attack step to yield formal [2+2+1]/[4+2] annulation products. These two annulation products arise initially from two seven-membered heterocyclic intermediates, which then lead to products.
- Sahani, Rajkumar Lalji,Liu, Rai-Shung
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supporting information
p. 1026 - 1030
(2017/01/18)
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- 3-Phenothiazinyl propiolates – Fluorescent electrophores by Sonogashira coupling of ethyl propiolate
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Fluorescent ethyl 3-phenothiazinyl propiolates with reversible Nernstian oxidation potentials were efficiently synthesized by an improved Sonogashira coupling of aryl iodides and ethyl propiolate. The versatility of this modified alkynylation was illustrated by 13 ethyl 3-arylpropiolates in mostly excellent yields with a broad substrate scope. In addition to reversible one-electron oxidations, the title compounds reveal large Stokes shifts, high fluorescence quantum yields, and solvatochromic emission. The photophysical characteristics were corroborated and rationalized by DFT and TD-DFT calculations.
- G?tzinger, Alissa C.,Michaelis, Carina S.,Müller, Thomas J.J.
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p. 308 - 316
(2017/05/04)
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- Rhodium-catalyzed C(sp2)-H addition of arylboronic acids to alkynes using a boron-based, convertible ortho-directing group
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Temporary modification of a boronyl group with pyrazoryl-aniline allowed insertion of arylpropiolates and diphenylacet-ylenes into the o-C-H bond of arylboronic acids in the presence of rhodium catalysts, giving 3,3-diarylacrylates and triarylethene conta
- Yamamoto, Takeshi,Ishibashi, Aoi,Suginome, Michinori
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supporting information
p. 1169 - 1172
(2017/08/07)
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- Enantioselective synthesis of β-fluoro-β-aryl-α-aminopentenamides by organocatalytic [2,3]-sigmatropic rearrangement
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The tetramisole-promoted catalytic enantioselective [2,3]-sigmatropic rearrangement of quaternary ammonium salts bearing a (Z)-3-fluoro-3-arylprop-2-ene group generates, after addition of benzylamine, a range of β-fluoro-β-aryl-α-aminopentenamides containing a stereogenic tertiary fluorine substituent. Cyclic and acyclic nitrogen substituents as well as various aromatic substituents are tolerated, giving the β-fluoro-β-aryl-α-aminopentenamide products in up to 76% yield, 96:4 dr, and 98:2 er.
- Kasten, Kevin,Slawin, Alexandra M. Z.,Smith, Andrew D.
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supporting information
p. 5182 - 5185
(2017/11/06)
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- Gold(I)/Chiral N,N′-Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement
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A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π-acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′-dioxide–nickel(II) complex. A range of acyclic α-allyl β-keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee) under mild reaction conditions. These products can be easily transformed into optically active β-hydroxy esters, β-hydroxy acids, or 1,3-diols.
- Li, Jun,Lin, Lili,Hu, Bowen,Zhou, Pengfei,Huang, Tianyu,Liu, Xiaohua,Feng, Xiaoming
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supporting information
p. 885 - 888
(2017/01/13)
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- Copper(i)/phosphine-catalyzed tandem carboxylation/annulation of terminal alkynes under ambient pressure of CO2: One-pot access to 3a-hydroxyisoxazolo[3,2-a]isoindol-8(3aH)-ones
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An efficient method for the synthesis of 3a-hydroxyisoxazolo[3,2-a]isoindol-8(3aH)-ones from CO2, terminal alkynes, EtBr, and NHPI (N-hydroxyphthalimide) was developed through a tandem carboxylation/annulation strategy catalyzed by a copper(i)/phosphine system. This one-pot multicomponent reaction was conducted at atmospheric CO2 pressure to afford the target products in good to excellent yields under mild conditions. Notably, a wide range of functional groups were tolerated in this procedure. This protocol with simultaneous formation of four novel bonds i.e. two C-C bonds and two C-O bonds represents an efficient methodology for upgrading CO2 into heterocycles.
- Xie, Jia-Ning,Yu, Bing,Guo, Chun-Xiang,He, Liang-Nian
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p. 4061 - 4067
(2015/07/15)
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- Three-component domino process for the pyrrolizine skeleton via [3 + 2]-cycloaddition-enamine cyclization triggered by a gold catalyst
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Pyrrolizines are bicyclic fused azaheterocycles with a bridgehead nitrogen contained in a core skeleton and are often found in biologically active compounds. Despite their importance, there have been few reports on concise and flexible syntheses of pyrrolizines. A novel one-pot, convergent method is described for pyrrolizines by simple mixing of iminoesters, acetylenes, and dipolarophiles in the presence of a cationic gold catalyst and an acid additive. This domino process affords multisubstituted pyrrolizines without handling unstable intermediates.
- Sugimoto, Kenji,Yamamoto, Nozomi,Tominaga, Daisuke,Matsuya, Yuji
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p. 1320 - 1323
(2015/03/14)
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- Copper(II)-Catalyzed β-Borylation of Acetylenic Esters in Water
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A method for the β-borylation of alkynoates has been developed. In the presence of bis(pinacolato)diboron and catalytic amounts of both copper(II) and 4-picoline, substituted alkynoates undergo borylation in a regio-, stereo-, and chemoselective fashion. The reaction is performed under mild conditions using water as solvent and open to the atmosphere to exclusively afford (Z)-β-boryl-α,β-unsaturated esters.
- Peck, Cheryl L.,Calderone, Joseph A.,Santos, Webster L.
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supporting information
p. 2242 - 2248
(2015/08/03)
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- Gold-catalyzed formal [4π+2π]-cycloadditions of tert-butyl propiolates with aldehydes and ketones to form 4H-1,3-dioxine derivatives
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Gold-catalyzed formal hetero-[4π+2π] cycloadditions of tert-butyl propiolates with carbonyl compounds proceeded efficiently to yield 4H-1,3-dioxine derivatives over a wide scope of substrates. With acetone as a promoter, gold-catalyzed cycloadditions of these propiolate derivatives with enol ethers led to the formation of atypical [4+2]-cycloadducts with skeletal rearrangement.
- Karad, Somnath Narayan,Chung, Wei-Kang,Liu, Rai-Shung
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supporting information
p. 13004 - 13007
(2015/08/06)
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- Minimizing Aryloxy Elimination in RhI-Catalyzed Asymmetric Hydrogenation of β-Aryloxyacrylic Acids using a Mixed-Ligand Strategy
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The first example of efficient asymmetric hydrogenation of challenging β-aryloxyacrylic acids was realized using a RhI-complex based on the heterocombination of a readily available chiral monodentate secondary phosphine oxide (SPO) and an achiral monodentate phosphine ligand as the catalyst. Excellent enantioselectivities (92->99% ee) were achieved for a wide variety of chiral β-aryloxypropionic acids with minor aryloxy elimination in most cases. The resultant products were readily transformed into biologically active compounds through simple synthetic manipulations.
- Li, Yang,Wang, Zheng,Ding, Kuiling
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supporting information
p. 16387 - 16390
(2015/11/09)
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- Visible-Light-Promoted Vinylation of Tetrahydrofuran with Alkynes through Direct C-H Bond Functionalization
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(Chemical Equation Presented) Mild and direct C-H bond functionalizations and vinylations of tetrahydrofuran with alkynes have been accomplished through visible light photocatalysis, yielding a range of vinyl tetrahydrofurans under the synergistic actions of organic dye-type photocatalyst eosin Y, tert-butyl hydroperoxide (t-BuOOH), and a 45 W household lightbulb. A significant kinetic isotope effect (KIE) was recorded, which helps shed light on the mechanistic course.
- Li, Jing,Zhang, Jing,Tan, Haibo,Wang, David Zhigang
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supporting information
p. 2522 - 2525
(2015/05/27)
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- Investigation of quantitative structure-reactivity relationships in the aliphatic Claisen rearrangement of bis-vinyl ethers reveals a dipolar, dissociative mechanism
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Kinetic investigations of substituent effects in the thermal rearrangement of bis-vinyl ether substrates are reported. Findings indicate that the influence of the various substituent patterns on the rate of rearrangement in these compounds differs from that documented in the literature for the analogous [3,3]-sigmatropic rearrangement of allyl vinyl ethers. In addition, the thermochemical data collected suggests the existence of a dissociative transition state with significant dipolar character. These findings provide a unique contribution to the already extensive body of literature dedicated to mechanistic investigation of the Claisen rearrangement of aliphatic allyl vinyl ethers.
- O'Rourke, Natasha F.,Wulff, Jeremy E.
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p. 1292 - 1308
(2014/03/21)
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- Gold-catalyzed 1,2-iminonitronation of electron-deficient alkynes with nitrosoarenes to afford α-imidoyl nitrones
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Gold-catalyzed 1,2-iminonitronation of propiolate derivatives with nitrosoarenes to give α-imidoyl nitrones is described; this new reaction is applicable to diverse propiolate derivatives and nitrosoarenes.
- Singh, Rahulkumar Rajmani,Liu, Rai-Shung
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p. 15864 - 15866
(2015/01/08)
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- Synthesis of ethyl arylpropiolates through palladium-catalyzed cross-coupling reactions of aryl iodides with in situ generated lithium tetrakis(ethoxycarbonylethynyl)indates
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An efficient synthetic method to access ethyl arylpropiolates has been developed; it involves a palladium-catalyzed cross-coupling reaction between a wide range of aryl iodides and lithium tetrakis(ethoxycarbonylethynyl)indates (0.35 equiv) generated in situ from indium trichloride and alkynides obtained from ethyl propiolate and n-butyllithium. Georg Thieme Verlag Stuttgart. New York.
- Park, Youngchul,Kang, Dongjin,Jeon, Woo Hyung,Ryu, Taekyu,Lee, Phil Ho
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p. 2305 - 2311
(2014/11/08)
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- Copper(II)-catalyzed silylation of activated alkynes in water: Diastereodivergent access to E- or Z-β-silyl-α,β-unsaturated carbonyl and carboxyl compounds
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Copper(II)-catalyzed silylation of substituted alkynylcarbonyl compounds was investigated. Through the activation of Me2PhSiBpin in water at room temperature and open atmosphere, vinylsilanes conjugated to carbonyl groups are synthesized in high yield. A surprising diastereodivergent access to olefin geometry was discovered using a silyl conjugate addition strategy: aldehydes and ketones were Z selective while esters and amides were exclusively transformed into the E products. Dial a diastereomer: The title reaction proceeds through the activation of Me2PhSiBpin in water at room temperature and open atmosphere to produce high yields of vinylsilanes conjugated to carbonyl groups. A surprising diastereodivergent access to olefin geometry was discovered using this silyl conjugate addition strategy: aldehydes were Z selective while esters and amides exclusively delivered the E-configured products.
- Calderone, Joseph A.,Santos, Webster L.
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supporting information
p. 4154 - 4158
(2014/05/06)
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- Ruthenium-catalyzed asymmetric [2 + 2] cycloadditions between chiral acyl camphorsultam-substituted alkynes and bicyclic alkenes
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Ruthenium-catalyzed asymmetric [2 + 2] cycloadditions between chiral acyl camphorsultam-functionalized alkynes and bicyclic alkenes were examined, providing adducts with complete exo stereoselectivity in good overall yield and enantioselectivity (up to 99% and 166:1, respectively), as well as appreciable diastereoselectivity (up to 163:1). The diastereoselectivity showed dependence on the solvent and temperature, as well as on the substitution pattern of the reacting alkyne and bicyclic alkene components. In general, higher diastereoselectivities were observed for reactions conducted in ethereal solvents and at lower temperatures between N-propynoyl camphorsultams and bicyclic alkenes.
- Goodreid, Jordan,Villeneuve, Karine,Carlson, Emily,Tam, William
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p. 10002 - 10012
(2015/02/19)
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- A convenient regioselective synthesis of cyclopentadienones via palladium-catalyzed [2+2+1] cyclocarbonylation of alkynes
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A simple and efficient synthesis of cyclopentadienones via palladium-catalyzed cyclocarbonylation of alkynes under atmospheric pressure of carbon monoxide has been developed. The transformation was carried out under mild and ligand-free conditions, a wide range of substrates and exceptional functional group tolerance.
- Xu, Yanli,Zhao, Jinwu,Chen, Huoji,Wu, Wanqing,Jiang, Huanfeng
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supporting information
p. 2488 - 2490
(2014/03/21)
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- Gold catalysis coupled with visible light stimulation: Syntheses of functionalized indoles
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A judicious combination of Au-catalysis and synergistic visible-light stimulation formulates an exceptionally simple and mild reaction system capable of directly coupling anilines and alkynes to form multifunctionalized indoles.
- Cai, Shunyou,Yang, Kai,Wang, David Zhigang
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supporting information
p. 2606 - 2609
(2014/06/09)
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- Synthesis of α,β-alkynyl esters and unsymmetrical maleate esters catalyzed by pd/c; An efficient phosphine-free catalytic system for oxidative alkoxycarbonylation of terminal alkynes
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Pd/C-catalyzed oxidative alkoxycarbonylation of terminal alkynes using alcohols in the presence of tetrabutylammonium iodide under CO/O2 (5:1 atm) has been investigated. The desired α,β-alkynyl esters and unsymmetrical maleate esters are formed in good to excellent yields under different reaction conditions. The present protocol eliminates the use of phosphine ligands and has straightforward catalyst recovery. The catalyst was recycled up to six times without significant loss of catalytic activity. Georg Thieme Verlag Stuttgart . New York.
- Gadge, Sandip T.,Bhanage, Bhalchandra M.
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supporting information
p. 981 - 986
(2013/06/27)
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- The reaction of substituted ethyl α-bromocinnamates with tetrabutyl ammonium fluoride
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The reaction of ethyl α-bromocinnamates with tetrabutyl ammonium fluoride (TBAF) was influenced largely by the position of the substituent at the phenyl ring. While the substrates without an ortho substituent at the phenyl ring were transformed to the cor
- Liang, Yan,Zhang, Ying Peng,Yu, Wei
-
experimental part
p. 777 - 780
(2012/08/27)
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- Ruthenium-catalyzed [2+2] cycloaddition reactions of a 2-oxa-3- azabicyclo[2.2.1]hept-5-ene with unsymmetrical alkynes
-
Ruthenium-catalyzed [2+2] cycloaddition reactions of a 2-oxa-3- azabicyclo[2.2.1]hept-5-ene with unsymmetrical alkynes were investigated. Yields of up to 90% were obtained though regioselectivity was modest. Select cycloadducts could be separated and used to access a highly functionalized [3.2.0] bicyclic structure through reductive cleavage of the N-O bond. These ring-opened products displayed a chemical exchange phenomenon in 1D carbon NMR and required characterization by 2D NMR techniques.
- Durham, Robin,Mandel, Jeremie,Blanchard, Nicolas,Tam, William
-
scheme or table
p. 1494 - 1505
(2012/01/12)
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- Highly effective copper-catalyzed decarboxylative coupling of aryl halides with alkynyl carboxylic acids
-
We have developed a highly effective copper-catalyzed decarboxylative coupling of alkynylcarboxylic acids with various aryl and alkyl halides at 2 mol% loading of copper. This method is simple, economical and practical for the synthesis of disubstituted alkyne compounds.
- Qu, Xiaoming,Li, Tingyi,Sun, Peng,Zhu, Yan,Yang, Hailong,Mao, Jincheng
-
scheme or table
p. 6938 - 6942
(2011/10/31)
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- Ligand-free copper(Ι)-catalyzed Sonogashira-type coupling of arylboronic acids with terminal alkynes
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An efficient ligand-free CuI-catalyzed Sonogashira-type coupling reaction of arylboronic acids with terminal alkynes under air is described. The electron-deficient alkynes gave the desired cross-coupling products in good yields. Thus, it represents a simple and alternative method for the traditional Sonogashira reaction.
- Pan, Changduo,Luo, Fang,Wang, Wenhui,Ye, Zhishi,Cheng, Jiang
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supporting information; scheme or table
p. 5044 - 5046
(2009/12/05)
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- New synthesis of t-butyl arylpropiolates using diazo(trimethylsilyl)methylmagnesium bromide
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Diazo(trimethylsilyl)methylmagnesium bromide smoothly reacted with t-butyl aryl(oxo)acetates to afford the corresponding arylpropiolates via alkylidenecarbene intermediates. In this reaction system, the magnesium bromide salt of trimethylsilyldiazomethane was significantly efficient compared to the lithium one, commonly known as a reagent for the conversion of aldehydes and aryl ketones into acetylenes.
- Hari, Yoshiyuki,Date, Koji,Kondo, Ryosuke,Aoyama, Toyohiko
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p. 4965 - 4967
(2008/09/21)
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- Preparation of α-bromoacrylates: One-pot procedure for the synthesis of conjugated acetylenic carboxylates from aldehydes with Ph3P/ Br3CCO2Et
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We have established the optimal conditions for the Wittig reaction for synthesizing α-bromoacrylates with a high selectivity, and developed a simple and efficient one-pot procedure for preparing various conjugated acetylenic carboxylates in moderate to high yields. Georg Thieme Verlag Stuttgart.
- Kim, Joong-Gon,Dong, Ho Kang,Doo, Ok Jang
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p. 443 - 447
(2008/04/01)
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- Facile one-pot synthesis of functionalized acetylenes from aryl and heteroaryl aldehydes using lithium trimethylsilyldiazomethane
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The reaction of aryl and heteroaryl aldehydes with lithium trimethylsilyldiazomethane followed by treatment with n-BuLi and then electrophiles in one-pot efficiently afforded functionalized acetylenes.
- Hari, Yoshiyuki,Date, Koji,Aoyama, Toyohiko
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p. 545 - 552
(2008/09/18)
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- Straightforward synthesis of 2-aryl-1-alkynylphosphonates and arylpropiolates
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A protocol for the direct cross coupling of trialkylsilyl-alkynes bearing electron-withdrawing groups and aryl halides using a Pd/Ag catalytic system is described. The procedure allows the straightforward synthesis of a variety of alkynylphosphonates and aryl propiolates derivatives in good yields. Copyright Taylor & Francis Group, LLC.
- Lecercle, Delphine,Mothes, Celine,Taran, Frederic
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p. 1301 - 1311
(2008/02/01)
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- TACHYKININ RECEPTOR ANTAGONISTS
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The present invention relates to selective NK-1 receptor antagonists of Formula (I) or a pharmaceutically acceptable salt thereof, for the treatment of disorders associated with an excess of tachykinins.
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- Oxidation of aromatic compounds: XII. Regio- and stereoselective oxidative dimerization of alkyl 3-arylpropynoates in the system CF3CO 2H-CH2Cl2-PbO2
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Regio- and stereoselective oxidative dimerization of alkyl 3-arylpropynoates in the system CF3CO2H-CH 2Cl2-PbO2 (1-30 h, 0-20°C) leads to dialkyl (E)-2,3-bis(arylcarbonyl)-2-butene-1,4-dioates with trans arrangement of the substituents at the double bond.
- Savechenkov,Vasil'ev,Rudenko
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p. 1279 - 1283
(2007/10/03)
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- The syntheses of cyclic spermine alkaloids: Analogues of buchnerine and budmunchiamine C
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The syntheses of two macrocyclic spermine alkaloids, analogues 1 and 2 of budmunchiamine C and buchnerine, in which N,N′-bis(2-aminoethyl)hexane-1,6-diamine (PA 262; 4) replaces spermine as polyamine backbone, were accomplished by two different methods. The first synthetic approach was based on a metal-template intramolecular amidation of tetraamino esters prepared from a Michael addition of protected PA 262 10 to ethyl hexadec-2-ynoate (12) and ethyl prop-2-ynoate 17. respectively (see Schemes 4 and 5. resp.). The consecutive Michael addition of ethane-1,2-diamine to unsaturated esters and aminolysis was employed in the second synthetic approach to prepare the precursors 23 and 24 (Scheme 6). The macrocyclic lactams were then constructed by macrocyclization of sulfonamido derivatives 25 and 26 in DMF with Cs2CO3 as catalyst.
- Li, Yi,Hesse, Manfred
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p. 310 - 323
(2007/10/03)
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- Substituted indoles and their use as integrin antagonists
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The present invention relates to novel substituted indole compounds that are antagonists of alpha V (αv) integrins, for example αvβ3 and αvβ5 integrins, their pharmaceutically acceptable salts, and pharmaceutical compositions thereof. The compounds may be used in the treatment of pathological conditions mediated by αvβ3 and αvβ5 integrins, including such conditions as tumor growth, metastasis, restenosis, osteoporosis, inflammation, macular degeneration, diabetic retinopathy, and rheumatoid arthritis. The compounds have the general formula: where R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R14, D, X, W, a, m, n, i, j, k and v are defined herein.
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- Diaryl-enynes
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Provided, among other things, is a compound of Formula I: wherein: Ar1and Ar2are independently selected aryl groups, optionally substituted with up to five substituents independently selected from the group consisting of alkyl, alkox
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- Metal-Templated Macrolactamization of Triamino and Tetramino Esters. Facile Synthesis of Macrocyclic Spermidine and Spermine Alkaloids, (S)-(+)-Dihydroperiphylline, (±)-Buchnerine, (±)-Verbacine, (±)-Verbaskine, and (±)-Verbascenine
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The total synthesis of spermidine and spermine alkaloids. (S)-(+)-dihydroperiphylline (1), (±)-buchnerine (2), (±)-verbacine (3), (±)-verbaskine (4), and (±)-verbascenine (5), is described. The construction of macrocyclic lactams has been efficiently accomplished by the metal-templated cyclization of triamino esters and tetraamino esters. It was also found that the antimony(III) ethoxide is useful as an intermolecular amidation catalyst.
- Kuroki, Yoshichika,Ishihara, Kazuaki,Hanaki, Naoyuki,Ohara, Suguru,Yamamoto, Hisashi
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p. 1221 - 1230
(2007/10/03)
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- Enantioselective Catalytic Epoxidation of Cinnamate Esters
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A broad study of the (salen)Mn(III)-catalyzed asymmetric epoxidation of cis-cinnamate esters reveals that the steric properties of the ester group have a profound influence on enantioselectivity in the epoxidation reaction, with bulkier esters affording highest ee's.The sensitivity of the reaction selectivity to the steric properties of the cis-alkene are consistent with a "skewed" side-on approach of olefin to the metal -oxo.The electronic properties of the substrate arene ring substituents do not correlate with epoxidation ee, but instead with the cis/trans partitioning of product formation.Evidence is provided for a non-polar inter mediate in a stepwise oxygen-atom-transfer mechanism.The presence of pyridine N-oxide derivatives has a significant effect on catalysts rates and total turnovers, but negligible influence on the stereoselectivity of epoxidation.A mechanistic basis for the role of these additives is proposed.The synthetic applicability of the cinnamate epoxidation methodology is illustrated in the highly enantioslective synthesis of diltiazem.
- Jacobsen, Eric N.,Deng, Li,Furukawa, Yoshiro,Martinez, Luis E.
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p. 4323 - 4334
(2007/10/02)
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- Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 2. Two-step Conversion of Acid Chlorides into Acetylenic Esters and Terminal Alkynes
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The known thermal extrusion of Ph3PO from α-acyl-α-ethoxycarbonyl ylides 1 to give acetylenic esters 2 can be accomplished in excellent yield by using flash vacuum (FVP) at 500 deg C.Upon rasing the furnace temperature to 750 deg C, this reaction is accompanied by unexpected loss of the ethoxycarbonyl group to give the terminal alkynes 7 in moderate yield.A mechanism is proposed for this reaction based on isotopic labelling studies.Ten new examples of ylides 1 have been prepared for the first time.
- Aitken, R. Alan,Horsburg, Caroline E. R.,McCreadie, J. Graeme,Seth, Shirley
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p. 1727 - 1732
(2007/10/02)
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- Preparation of ethyl arylpropiolates from aryl iodides by palladium-catalyzed cross-coupling reaction
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The palladium-catalyzed cross-coupling reaction of aryl iodides with 3,3,3-triethoxy-1-propyne gave 1-aryl-3,3,3-triethoxy-1-propynes which were converted to the corresponding ethyl arylpropiolates. The arylpropiolates were also synthesized from the cross-coupling reactions of aryl iodides with 2-ethoxycarbonyl-1-ethynylzinc chloride or ethyl (tributylstannyl)propiolate, but the reactions were not generally applicable.
- Sakamoto,Shiga,Yasuhara,Uchiyama,Kondo,Yamanaka
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p. 746 - 748
(2007/10/02)
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- Mild Palladium-catalysed Carbonylation of Alkynylphenyliodonium Toluene-p-sulphonates under Carbon Monoxide at Atmospheric Pressure
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Alkoxycarbonylation of alkynylphenyliodonium toluene-p-sulphonates catalysed by a palladium catalyst proceeded under carbon monoxide at atmospheric pressure at room temperature to give alkyne carboxylates in high yields.
- Kitamura, Tsugio,Mihara, Ichiro,Taniguchi, Hiroshi,Stang, Peter J.
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p. 614 - 615
(2007/10/02)
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