- An Enzymatic Platform for Primary Amination of 1-Aryl-2-alkyl Alkynes
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Propargyl amines are versatile synthetic intermediates with numerous applications in the pharmaceutical industry. An attractive strategy for efficient preparation of these compounds is nitrene propargylic C(sp3)-H insertion. However, achieving this reacti
- Liu, Zhen,Qin, Zi-Yang,Zhu, Ledong,Athavale, Soumitra V.,Sengupta, Arkajyoti,Jia, Zhi-Jun,Garcia-Borràs, Marc,Houk,Arnold, Frances H.
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supporting information
p. 80 - 85
(2022/01/08)
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- Z-Selective Synthesis of α-Sulfanyl Carbonyl Compounds from Internal Alkynes and Thiols via Photoredox Catalysis
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A synthetically useful Z-selective cascade formal thiyl radical addition, 1,3-double bond isomerization, oxygen trapping reaction, can be promoted by Eosin B under visible light, leading to the construction of 2-aryl- and alkylthio enone derivatives in good yields. An accurate study on the reactivity of different thiols and the screening of the reaction conditions, allowed us to extend this reaction to a large number of substrates, showing a good functional groups tolerance while highlighting the limitations of this procedure. Background experiments and mechanistic studies were also. performed to rationalize this cascade process. The usefulness of this methodology was finally demonstrated via the transformation of a series of α-sulfanyl-enone adducts through selected oxidation reactions, stereoselective synthesis of cyclopropyl ketones, indanones, and pyrazole compounds. (Figure presented.).
- Luridiana, Alberto,Frongia, Angelo,Scorciapino, Mariano Andrea,Malloci, Giuliano,Manconi, Barbara,Serrao, Simone,Ricci, Pier Carlo,Secci, Francesco
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supporting information
p. 124 - 131
(2021/10/12)
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- Hydromagnesiation of 1,3-Enynes by Magnesium Hydride for Synthesis of Tri- and Tetra-substituted Allenes
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A protocol for regio-controlled hydromagnesiation of 1,3-enynes was developed using magnesium hydride that is generated in situ by solvothermal treatment of sodium hydride (NaH) and magnesium iodide (MgI2) in THF. The resulting allenylmagnesium species could be converted into tri- and tetra-substituted allenes by subsequent treatment with various carbon- and silicon-based electrophiles with the aid of CuCN as a catalyst.
- Chiba, Shunsuke,Li, Yihang,Pang, Jia Hao,Takita, Ryo,Wang, Bin,Watanabe, Kohei
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p. 217 - 221
(2020/11/30)
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- Engineering Cytochrome P450s for Enantioselective Cyclopropenation of Internal Alkynes
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We report a biocatalytic platform of engineered cytochrome P450 enzymes to carry out efficient cyclopropene synthesis via carbene transfer to internal alkynes. Directed evolution of a serine-ligated P450 variant, P411-C10, yielded a lineage of engineered
- Chen, Kai,Arnold, Frances H.
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supporting information
p. 6891 - 6895
(2020/05/14)
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- CsF-Mediated in Situ Desilylation of TMS-Alkynes for Sonogashira Reaction
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A practical and mild set of conditions for the Sonogashira reaction utilizing CsF-mediated in situ TMS-alkyne desilylation followed by Sonogashira coupling has been developed for the synthesis of a variety of alkynyl benzenes and heteroarenes in good to excellent yields. This methodology demonstrates excellent functional group tolerance and simple purification, which allows large-scale industrial applications. This one-pot protocol enables a high-yielding Sonogashira coupling with volatile alkynes by avoiding challenging isolation of free alkynes.
- Capani, Joseph S.,Cochran, John E.,Liang, Jianglin
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p. 9378 - 9384
(2019/07/08)
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- Facile Access to Diverse Libraries of Internal Alkynes via Sequential Iododediazoniation/Decarboxylative Sonogashira Reaction in Imidazolium ILs without Ligand or Additive
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Convenient access to diverse libraries of internal alkynes via decarboxylative Sonogashira reaction of alkynyl-carboxylic acids with iodoarenes, employing imidazolium-ILs as solvent, along with piperidine-appended imidazolium [PAIM][NTf2] as task-specific basic IL is demonstrated, without the need for any ligand or additive. The feasibility to perform these reactions by sequential one-pot iododediazoniation/decarboxylative Sonogashira reaction is also shown, and the scope of the methods is underscored by providing 29 examples. The potential for recycling and reuse of the IL solvent is also examined.
- Prabhala, Pavankumar,Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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p. 2061 - 2064
(2019/03/07)
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- Multi-Metal-Catalyzed Oxidative Radical Alkynylation with Terminal Alkynes: A New Strategy for C(sp3)-C(sp) Bond Formation
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A new way for C(sp3)-C(sp) cross-coupling with terminal alkynes has been developed by using a multi-metal-catalyzed reaction strategy. Alkyl radicals generated from different approaches are able to couple with terminal alkynes by judicious selection of the catalyst combination. This reaction protocol offers an efficient alternative approach for the synthesis of substituted alkynes from terminal alkynes besides traditional Sonogashira coupling. Mechanistic studies have also been carried out to clarify the role of each metal catalyst in the radical alkynylation processes. The reactions were found to go through radical reaction pathways. Synergistic cooperation of the metal catalysts is the key for controlling the reaction selectivity of alkyl radicals toward C(sp3)-C(sp) bond formation.
- Tang, Shan,Liu, Yichang,Gao, Xinlong,Wang, Pan,Huang, Pengfei,Lei, Aiwen
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supporting information
p. 6006 - 6013
(2018/05/14)
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- Decarboxylative/Sonogashira-type cross-coupling using PdCl2(Cy?Phine)2
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The PdCl2(Cy?Phine)2 precatalyst containing the meta-terarylphosphine ligand, Cy?Phine, can effectively mediate decarboxylative cross-coupling with a diverse range of (hetero-)aryl, aryl and alkyl chlorides including those with unprotected functionality. Using a facile and robust protocol, this process was extended to the first synthesis of symmetrical di(heteroaryl)alkynes via tandem Sonogashira/decarboxylative cross-coupling of heteroaryl chlorides and propiolic acid.
- Yang, Yong,Lim, Yee Hwee,Robins, Edward G.,Johannes, Charles W.
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p. 72810 - 72814
(2016/08/09)
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- Palladium and copper catalyzed Sonogashira decarboxylative coupling of aryl iodides and alkynyl carboxylic acids
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A mild procedure of palladium and copper catalyzed decarboxylative cross-coupling reaction of aryl halides and alkynyl carboxylic acids has been developed. Low molecular weight acids, to introduce small building blocks, were specifically used. This method
- Maaliki, Carine,Chevalier, Yoan,Thiery, Emilie,Thibonnet, Jér?me
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supporting information
p. 3358 - 3362
(2016/07/11)
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- Copper-catalyzed C(sp2)-C(sp) Sonogashira-type cross-coupling reactions accelerated by polycyclic aromatic hydrocarbons
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Copper-catalyzed Sonogashira-type reactions were dramatically accelerated by introducing a catalytic amount of polycyclic aromatic hydrocarbon additive. This novel catalytic system features low copper loading (0.5mol% Cu 5mol%), broad reaction scope a
- Xu, Wei,Yu, Bo,Sun, Huaming,Zhang, Guofang,Zhang, Weiqiang,Gao, Ziwei
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p. 353 - 356
(2015/06/02)
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- Synthetic, mechanistic, and computational investigations of nitrile-alkyne cross-metathesis
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The terminal nitride complexes NW(OC(CF3)2Me) 3(DME) (1-DME), [Li(DME)2][NW(OC(CF3) 2Me)4] (2), and [NW(OCMe2CF3) 3]3 (3) were prepared in good yield by salt elimination from [NWCl3]4. X-ray structures revealed that 1-DME and 2 are monomeric in the solid state. All three complexes catalyze the cross-metathesis of 3-hexyne with assorted nitriles to form propionitrile and the corresponding alkyne. Propylidyne and substituted benzylidyne complexes RCW(OC(CF3)2Me)3 were isolated in good yield upon reaction of 1-DME with 3-hexyne or 1-aryl-1-butyne. The corresponding reactions failed for 3. Instead, EtCW(OC(CF3)Me2) 3 (6) was prepared via the reaction of W2(OC(CF 3)Me2)6 with 3-hexyne at 95°C. Benzylidyne complexes of the form ArCW(OC(CF3)Me2)3 (Ar = aryl) then were prepared by treatment of 6 with the appropriate symmetrical alkyne ArCCAr. Three coupled cycles for the interconversion of 1-DME with the corresponding propylidyne and benzylidyne complexes via [2 + 2] cycloaddition-cycloreversion were examined for reversibility. Stoichiometric reactions revealed that both nitrile-alkyne cross-metathesis (NACM) cycles as well as the alkyne cross-metathesis (ACM) cycle operated reversibly in this system. With catalyst 3, depending on the aryl group used, at least one step in one of the NACM cycles was irreversible. In general, catalyst 1-DME afforded more rapid reaction than did 3 under comparable conditions. However, 3 displayed a slightly improved tolerance of polar functional groups than did 1-DME. For both 1-DME and 3, ACM is more rapid than NACM under typical conditions. Alkyne polymerization (AP) is a competing reaction with both 1-DME and 3. It can be suppressed but not entirely eliminated via manipulation of the catalyst concentration. As AP selectively removes 3-hexyne from the system, tandem NACM-ACM-AP can be used to prepare symmetrically substituted alkynes with good selectivity, including an arylene-ethynylene macrocycle. Alternatively, unsymmetrical alkynes of the form EtCCR (R variable) can be prepared with good selectivity via the reaction of RCN with excess 3-hexyne under conditions that suppress AP. DFT calculations support a [2 + 2] cycloaddition-cycloreversion mechanism analogous to that of alkyne metathesis. The barrier to azametalacyclobutadiene ring formation/breakup is greater than that for the corresponding metalacyclobutadiene. Two distinct high-energy azametalacyclobutadiene intermediates were found. These adopted a distorted square pyramidal geometry with significant bond localization.
- Geyer, Andrea M.,Wiedner, Eric S.,Gary, J. Brannon,Gdula, Robyn L.,Kuhlmann, Nicola C.,Johnson, Marc J. A.,Dunietz, Barry D.,Kampf, Jeff W.
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scheme or table
p. 8984 - 8999
(2009/02/03)
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- Catalytic nitrile-alkyne cross-metathesis
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The first catalytic cross-metathesis reaction of an alkyne with a nitrile is described. The nitride complex N≡W(OC(CF3)2CH3)3(DME) undergoes reversible triple-bond metathesis reactions with alkynes (RC≡CR; R = Et, 4-C6H4OMe), forming the alkylidyne complexes RC≡W(OC(CF3)2CH3)3(DME) (R = Et, 4-C6H4OMe) along with the corresponding nitrile RC≡N. This has been exploited to effect catalytic cross-metathesis of nitriles with alkynes, in which the organic CR fragments of two nitriles are coupled to yield an alkyne. A simple "sacrificial" alkyne (3-hexyne) acts as the N-atom acceptor, forming two equivalents of nitrile byproduct (propionitrile). Copyright
- Geyer, Andrea M.,Gdula, Robyn L.,Wiedner, Eric S.,Johnson, Marc J. A.
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p. 3800 - 3801
(2008/02/03)
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- Indium tribromide-catalyzed deacetoxylation of propargylic acetate with triethylsilane
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Indium(III) bromide catalyzed the deacetoxylation of propargylic acetates with Et3SiH to produce the corresponding internal alkynes containing a variety of functional groups in good yields.
- Sakai, Norio,Hirasawa, Maki,Konakahara, Takeo
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p. 6407 - 6409
(2007/10/03)
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- Highly Active Trialkoxymolybdenum(VI) Alkylidyne Catalysts Synthesized by A Reductive Recycle Strategy
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A systematic study of alkyne metathesis catalyzed by trialkoxymolybdenum(VI) alkylidyne complexes is reported, in which substrate functional groups, alkynyl substituents, and catalyst ligands are varied. Sterically hindered trisamidomolybdenum(VI) propylidyne complex 5 was prepared conveniently through a previously communicated reductive recycle strategy. Alcoholysis of 5 with various phenols/alcohols provides a set of active catalysts for alkyne metathesis at room temperature, among which the catalyst with p-nitrophenol as ligand shows the highest catalytic activity and is compatible with a variety of functional groups and solvents. A key finding that enabled the use of highly active molybdenum(VI) catalysts is replacement of the commonly used propynyl substituents on the starting alkyne substrates with butynyl groups. Under reduced pressure using 1,2,4-trichlorobenzene as an involatile solvent, the alkyne metathesis of butynyl substituted compounds proceeds well at 30 °C providing high yields (83%-97%) of dimers. Rationalization of the special role played by butynyl substrates is discussed.
- Zhang, Wei,Kraft, Stefan,Moore, Jeffrey S.
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p. 329 - 335
(2007/10/03)
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