- Water-Soluble Phospholo[3,2-b]phosphole-P,P′-Dioxide-Based Fluorescent Dyes with High Photostability
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We recently reported that fluorescent dye PB430, which consisted of a 2-phenyl-substituted benzophosphole P-oxide skeleton that was reinforced by a methylene bridge, showed pronounced photostability and, thus, high utility for applications in super-resolution stimulated emission depletion (STED) microscopy. Herein, we replaced the methylene bridge with another P=O group to 1) investigate the role of the bridging moieties; and 2) further modulate the fluorescence properties of this skeleton. We synthesized a series of phospholo[3,2-b]phosphole-based dyes—trans-PO-PB430, cis-PO-PB430, and trans-PO-PB460—all of which showed sufficient water solubility. Moreover, trans-PO-PB430 and trans-PO-PB460 exhibited intense green and orange fluorescence, respectively, and a high photostability that was comparable to that of PB430. In contrast, cis-PO-PB430 underwent rapid photobleaching upon continuous photoirradiation, which demonstrated the importance of steric shielding of the polycyclic skeleton by the substituents on the bridging moieties. The fluorescence properties of these dyes were insensitive to concentration, pH value, and polarity changes of the environment in solution. In addition, even in the solid state, these dyes showed strong green to orange emissions. These results demonstrate the potential utility of trans-PO-PB430 and trans-PO-PB460 as highly photostable fluorescent dyes.
- Wang, Chenguang,Fukazawa, Aiko,Tanabe, Yoshiyuki,Inai, Naoto,Yokogawa, Daisuke,Yamaguchi, Shigehiro
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- Ni-Catalyzed Synthesis of Thiocarboxylic Acid Derivatives
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A Ni-catalyzed cross-coupling of readily accessible O-alkyl xanthate esters or thiocarbonyl imidazolides and organozinc reagents for the synthesis of thiocarboxylic acid derivatives has been developed. This method benefits from a fast reaction time, mild reaction conditions, and ease of starting material synthesis. The use of transition-metal catalysis to access a diverse range of thiocarbonyl-containing compounds provides a useful complementary approach when compared with previously established methodologies.
- Monteith, John J.,Scotchburn, Katerina,Mills, L. Reginald,Rousseaux, Sophie A. L.
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supporting information
p. 619 - 624
(2022/01/20)
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- Enantiomerically Enriched α-Borylzinc Reagents by Nickel-Catalyzed Carbozincation of Vinylboronic Esters
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In this paper is described a synthesis of enantiomerically enriched, configurationally stable organozinc reagents by catalytic enantioselective carbozincation of a vinylboronic ester. This process furnishes enantiomerically enriched α-borylzinc intermediates that are shown to undergo stereospecific reactions, producing enantioenriched secondary boronic ester products. The properties of the intermediate α-borylzinc reagent are probed and the synthetic utility of the products is demonstrated by application to the synthesis of (-)-aphanorphine and (-)-enterolactone.
- Chen, Jingjia,Hu, Weipeng,Jin, Jing,Lovinger, Gabriel J.,Morken, James P.,Zhang, Chenlong
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supporting information
p. 14189 - 14195
(2021/09/11)
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- The Formation of P-C Bonds Utilizing Organozinc Reagents for the Synthesis of Aryl- A nd Heteroaryl-Dichlorophosphines
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Aryl- A nd heteroaryl-dichlorophosphines are mildly and selectively made in a one-pot synthesis in moderate to good yields starting from the respective aryl bromides or five-membered heterocycles, following lithiation with nBuLi, transmetalation with ZnCl
- Kirst, Christin,Tietze, Jonathan,Ebeling, Marian,Horndasch, Lukas,Karaghiosoff, Konstantin
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p. 17337 - 17343
(2021/11/18)
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- Ni-Catalyzed C(sp3)–O Arylation of α-Hydroxy Esters
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A Negishi cross-coupling of α-hydroxy ester derivatives and arylzinc reagents has been developed. This reaction tolerates both primary and secondary C(sp3)–O alcohol precursors and achieves efficient cross-coupling under Ni catalysis without the need for added external metal reductant, photocatalyst, or additives. The arylation of readily accessible C(sp3)–O electrophiles in this operationally simple, rapid, and mild reaction provides a complementary way of accessing desirable α-aryl ester products.
- Monteith, John J.,Rousseaux, Sophie A. L.
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supporting information
p. 9485 - 9489
(2021/12/09)
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- Direct Umpolung Morita–Baylis–Hillman like α-Functionalization of Enones via Enolonium Species
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Herein we report on the umpolung of Morita–Baylis–Hillman type intermediates and application to the α-functionalization of enone C?H bonds. This reaction gives direct access to α-chloro-enones, 1,2-diketones and α-tosyloxy-enones. The latter are important intermediates for cross-coupling reaction and, to the best of our knowledge, cannot be made in a single step from enones in any other way. The proposed mechanism is supported by spectroscopic studies. The key initial step involves conjugate attack of an amine (DABCO or pyridine), likely assisted by hypervalent iodine acting as a Lewis acid leading to formation of an electrophilic β-ammonium-enolonium species. Nucleophilic attack by acetate, tosylate, or chloride anion is followed by base induced elimination of the ammonium species to give the noted products. Hydrolysis of α-acetoxy-enones lead to formation of 1,2-diketones. The α-tosyl-enones participate in Negishi coupling reactions under standard conditions.
- Arava, Shlomy,Kapanaiah, Raja,Pathe, Gulab K.,Santra, Sourav K.,Szpilman, Alex M.
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supporting information
p. 15171 - 15175
(2020/07/04)
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- Palladium-catalyzed secondary benzylic imidoylative reactions
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Reported herein is a palladium-catalyzed secondary benzylic imidoylative Negishi reaction leveraging the sterically bulky aromatic isocyanides as the imine source. This method allows the facile access of alkyl-, (hetero)aryl-, and alkynylzinc reagents to afford various α-substituted phenylacetone products under mild acidic hydrolysis, which are ubiquitous motifs in many pharmaceuticals and biologically active compounds. The diastereoselective reduction of imine can be accomplished to provide the expedient conversion of secondary benzylic halide into α-substituted phenethylamine derivatives with high atom economy.
- Wang, Chenglong,Wu, Licheng,Xu, Wentao,He, Feng,Qu, Jingping,Chen, Yifeng
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supporting information
p. 6954 - 6959
(2020/09/15)
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- Asymmetric Synthesis of Alkylzincs by Rhodium-Catalyzed Enantioselective Arylative Cyclization of 1,6-Enynes with Arylzincs
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A chiral diene-rhodium complex was found to catalyze the reaction of 1,6-enynes with ArZnCl to give high yields of 2-(alkylidene)cyclopentylmethylzincs with high enantioselectivity (95–99 % ee). The enantioenriched alkylzincs were readily converted in a one-pot approach into a wide variety of functionalized products by taking advantage of their unique reactivity. The catalytic cylcle involves arylrhodation of alkyne, intramolecular alkenylrhodation of alkene, and transmetalation of the alkyl-rhodium intermediate into alkylzinc.
- Chen, Jiahua,Hayashi, Tamio
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supporting information
p. 18510 - 18514
(2020/08/21)
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- Copper-Catalyzed Electrophilic Thiolation of Organozinc Halides by Using N-Thiophthalimides Leading to Polyfunctional Thioethers
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(Hetero)aryl, benzylic, and alkyl zinc halides were thiolated with N-thiophthalimides at 25 °C within 1 h in the presence of 5–10 % Cu(OAc)2?H2O to furnish the corresponding polyfunctionalized thioethers in good yields. This electrop
- Gra?l, Simon,Hamze, Clémence,Koller, Thadd?us J.,Knochel, Paul
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supporting information
p. 3752 - 3755
(2019/02/13)
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- Modular Functionalization of Arenes in a Triply Selective Sequence: Rapid C(sp2) and C(sp3) Coupling of C?Br, C?OTf, and C?Cl Bonds Enabled by a Single Palladium(I) Dimer
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Full control over multiple competing coupling sites would enable straightforward access to densely functionalized compound libraries. Historically, the site selection in Pd0-catalyzed functionalizations of poly(pseudo)halogenated arenes has been unpredictable, being dependent on the employed catalyst, the reaction conditions, and the substrate itself. Building on our previous report of C?Br-selective functionalization in the presence of C?OTf and C?Cl bonds, we herein complete the sequence and demonstrate the first general arylations and alkylations of C?OTf bonds (in I dimer. This allowed the realization of the first general and triply selective sequential C?C coupling (in 2D and 3D space) of C?Br followed by C?OTf and then C?Cl bonds.
- Keaveney, Sinead T.,Kundu, Gourab,Schoenebeck, Franziska
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supporting information
p. 12573 - 12577
(2018/09/18)
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- Nickel-catalyzed cross-coupling of β-carbonyl alkenyl pivalates with arylzinc chlorides
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The nickel-catalyzed cross-coupling reaction of β-carbonyl alkenyl pivalates with arylzinc reagents generates 3-aryl-substituted α,β-unsaturated carbonyl compounds via C-O bond cleavage. The reaction features mild reaction conditions, a wide scope of substrates, and good functional group tolerance.
- Pan, Wen-Jing,Wang, Zhong-Xia
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p. 1029 - 1036
(2018/02/19)
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- Synthesis of some ketones via nano-nickel oxide catalyzed acylation of arylzinc reagents; strategy involving the use of mixed (methyl)(aryl)zincs
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Nano-NiO catalyzed acylation of mixed (methyl)(aryl)zincs with aromatic acyl halides in THF at room temperature provides a new facile route for aryl–aroyl coupling. Among NiCl2 .L2 and NiCl2 .L (L = monodentate and bidentate phosphine ligand) catalysts, the lower catalyst loading of NiCl2 (dppf) may seem attractive; however, nano-NiO, being the lowest cost catalyst, is more favorable for aroylation of (methyl)(aryl)zincs. This procedure also provides a supplement to Cu and Pd catalyzed acylation of diorganozincs.
- Pekel, ?zgen ?MüR,Erdik, Ender,Kalkan, Melike
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p. 759 - 767
(2018/06/07)
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- Rhodium-Catalyzed Arylzincation of Alkynes: Ligand Control of 1,4-Migration Selectivity
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The addition of arylzinc reagents ArZnCl 1 to alkynes 2 was found to be catalyzed by rhodium complexes in the presence of a catalytic amount of zinc chloride. The selectivity in giving 2-arylalkenylzinc species 3 or ortho-alkenylarylzinc species 4, the la
- Ming, Jialin,Hayashi, Tamio
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p. 6188 - 6192
(2018/10/02)
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- Divergent Synthetic Access to E- and Z-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens
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A highly substrate-general synthesis of all-carbon-substituted E- and Z-stereodefined olefins is performed. The method comprises two sets of parallel and stereocomplementary preparations of (E)- and (Z)-α,β-unsaturated esters involving two robust and distinctive reactions: 1) stereocomplementary enol tosylations using readily available TsCl/diamine/(LiCl) base reagents, and 2) stereoretentive Negishi cross-coupling using the catalysts [Pd(dppe)Cl2] (for E) and [Pd(dppb)Cl2] (for Z). The present parallel approach is categorized as both type I (convergent approach: 16 examples, 56–87 % yield) and type II (divergent approach: 18 examples, 70–95 % yield). The obtained (E)- and (Z)-α,β-unsaturated ester scaffolds are successfully transformed into various E- and Z-stereodefined known and novel olefins (8×2 derivatization arrays). As a demonstration, application to the parallel synthesis of both (E)- and (Z)-tamoxifens, a representative motif of all-carbon-substituted olefins, is accomplished in a total of eight steps with an overall yield of 58 % (average 93 %) and 57 % (average 93 %), respectively.
- Ashida, Yuichiro,Honda, Atsushi,Sato, Yuka,Nakatsuji, Hidefumi,Tanabe, Yoo
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- Dehydration-type Ti-Claisen Condensation (Carbonhomologation) of α-Heteroatom-substituted Acetates with Alkyl Formates: Utilization as (Z)-Stereodefined Cross-coupling Partners and Application to Concise Synthesis of Strobilurin A
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TiCl4?Et3N or ?Bu3N reagent conducted a highly (Z)-stereoselective carbon homologation (dehydration type Ti-Claisen condensation) of alkyl α-heteroatom (halo and sulfonyloxy)-substituted acetates (XCH2CO2R) with alkyl formates (HCO2R) to afford various alkyl β-alkoxy-α-halo or sulfonyloxy-substituted acrylates (24 examples; 51%–91% yield). Stereoretentive Suzuki-Miyaura, Negishi, and Sonogashira cross-couplings using the obtained methyl β-methoxy-α-halo or sulfonyloxy-substituted acrylates proceeded smoothly to produce a variety of β-alkoxy-α-substituted acrylates in moderate to high yield (35 examples; 29%–99% yield). As a successful application, a 3-step straightforward synthesis of strobilurin A was performed utilizing the present reaction sequence (dehydration type Ti-Claisen condensation and Suzuki-Miyaura cross-coupling), wherein the geometry of the three consecutive olefins (2E,3Z,5E) was completely maintained. (Figure presented.).
- Nakatsuji, Hidefumi,Kamada, Risa,Kitaguchi, Hideya,Tanabe, Yoo
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p. 3865 - 3879
(2017/11/15)
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- Nickel-Catalyzed Negishi Cross-Coupling of N -Acylsuccinimides: Stable, Amide-Based, Twist-Controlled Acyl-Transfer Reagents via N-C Activation
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This paper reports a room temperature, nickel-catalyzed Negishi cross-coupling of N -acylsuccinimides with arylzinc reagents via selective N-C bond cleavage enabled by amide bond twist. The reaction proceeds using a commercially available, air-stable Ni(II) precatalyst in the absence of additives under exceedingly mild conditions. Of broad interest, this report introduces N -acylsuccinimides as stable, crystalline, electrophilic, cost-effective, benign, amide-based acyl transfer reagents via acyl metal intermediates. The reaction selectivity is governed by half-twist of the amide bond in N -acylsuccinimides, thus opening the door for applications in metal-catalyzed manifolds via redox-neutral reaction pathways tuneable by amide bond distortion.
- Shi, Shicheng,Szostak, Michal
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supporting information
p. 3602 - 3608
(2017/08/15)
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- Directed Zincation or Magnesiation of the 2-Pyridone and 2,7-Naphthyridone Scaffold Using TMP Bases
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A regioselective zincation of the 2-pyridone and 2,7-naphthyridone scaffolds has been developed. Zincations of the methoxyethoxymethyl (MEM)-protected compounds using TMP2Zn·2MgCl2·2LiCl (TMP = 2,2,6,6-tetramethylpiperidyl) followed
- Ziegler, Dorothée S.,Greiner, Robert,Lumpe, Henning,Kqiku, Laura,Karaghiosoff, Konstantin,Knochel, Paul
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supporting information
p. 5760 - 5763
(2017/11/10)
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- Transition-Metal-Free Cross-Coupling of Aryl and Heteroaryl Thiols with Arylzinc Reagents
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Cross-coupling of (hetero)arylthiols with arylzinc reagents via C-S cleavage was performed under transition-metal-free conditions. The reaction displays a wide scope of substrates and high functional-group tolerance. Electron-rich and -deficient (hetero)arylthiols and arylzinc reagents can be employed in this transformation. Mg2+ and Li+ ions were demonstrated to facilitate the reaction.
- Yang, Bo,Wang, Zhong-Xia
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supporting information
p. 6220 - 6223
(2017/11/24)
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- Preparation of Polyfunctional Naphthyridines by Cobalt-Catalyzed Cross-Couplings of Halogenated Naphthyridines with Magnesium and Zinc Organometallics
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CoCl2 (5%) catalyzes cross-couplings of various halogenated naphthyridines with alkyl- and arylmagnesium halides. Also, arylzinc halides undergo smooth cross-couplings with various naphthyridines in the presence of CoCl2·2LiCl (5%) a
- Greiner, Robert,Ziegler, Dorothée S.,Cibu, Denise,Jakowetz, Andreas C.,Auras, Florian,Bein, Thomas,Knochel, Paul
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supporting information
p. 6384 - 6387
(2017/12/08)
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- Investigation of a Late-Stage Derivatization Approach to Isatogens: Discovery of New Reaction Pathways
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We have developed a new strategy for preparing 2-substituted indolone N-oxides (isatogens) by substitution reactions with aryl- and alkyl-organometallic reagents. This approach allows a range of substituents to be incorporated at a late stage and complements existing methods that necessitate their early stage incorporation during substrate preparation. Further chemistry has been found to take place at the nitrone moiety; intramolecular dipolar cycloaddition provides access to angularly fused tricyclic heterocycles. More unusually however, these compounds are prone to further addition by organozinc reagents leading to 2,2-disubstituted 3-oxindole products.
- Edeson, Steven J.,Maduli, Elvis J. M.,Swanson, Stephen,Procopiou, Panayiotis A.,Harrity, Joseph P. A.
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supporting information
p. 83 - 86
(2016/01/26)
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- Mild Cobalt-Catalyzed Negishi Cross-Couplings of (Hetero)arylzinc Reagents with (Hetero)aryl Halides
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A catalytic system consisting of CoCl2?2 LiCl (5 mol %) and HCO2Na (50 mol %) enables the cross-coupling of various N-heterocyclic chlorides and bromides as well as aromatic halogenated ketones with various electron-rich and -poor ar
- Haas, Diana,Hammann, Jeffrey M.,Lutter, Ferdinand H.,Knochel, Paul
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p. 3809 - 3812
(2016/03/23)
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- Efficient Synthesis of Diaryl Ketones by Nickel-Catalyzed Negishi Cross-Coupling of Amides by Carbon–Nitrogen Bond Cleavage at Room Temperature Accelerated by a Solvent Effect
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The first Negishi cross-coupling of amides for the synthesis of versatile diaryl ketones by selective C?N bond activation under exceedingly mild conditions is reported. The cross-coupling was accomplished with bench-stable, inexpensive precatalyst [Ni(PPh3)2Cl2] that shows high functional-group tolerance and enables the synthesis of highly functionalized diaryl ketone motifs. The coupling occurred with excellent chemoselectivity favoring the ketone (cf. biaryl) products. Notably, this process represents the mildest conditions for amide N?C bond activation accomplished to date (room temperature, 10 min). Considering the versatile role of polyfunctional biaryl ketone linchpins in modern organic synthesis, availability, and excellent functional-group tolerance of organozinc reagents, this strategy provides a new platform for amide N?C bond/organozinc cross-coupling under mild conditions.
- Shi, Shicheng,Szostak, Michal
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supporting information
p. 10420 - 10424
(2016/07/21)
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- Rh-Catalyzed Conjugate Addition of Arylzinc Chlorides to Thiochromones: A Highly Enantioselective Pathway for Accessing Chiral Thioflavanones
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A highly efficient asymmetric synthesis of chiral thioflavanones is developed via conjugate addition of arylzinc reagents to thiochromones using Rh(COD)Cl2/(R)-3,4,5-MeO-MeOBIPHEP catalyst. This method overcomes catalyst poisoning and substrate inertness and affords a series of chiral thioflavanones (2-arylthiochroman-4-ones) in good yields (up to 91% yield) with excellent ee values (up to 97% ee). The established asymmetric synthesis paves the way for further pharmaceutical studies.
- Meng, Ling,Jin, Ming Yu,Wang, Jun
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supporting information
p. 4986 - 4989
(2016/10/14)
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- Nickel-catalyzed diaryl ketone synthesis by N-C cleavage: Direct negishi cross-coupling of primary amides by site-selective N,N-Di-boc activation
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A general Negishi acylation of primary amides enabled by a combination of site-selective N,N-di-Boc activation and nickel catalysis is reported for the first time. The reaction is promoted by a bench-stable, inexpensive Ni catalyst. The reaction shows excellent functional group compatibility, affording functionalized diaryl ketones by selective N-C cleavage. Most notably, this protocol represents the first amide cross-coupling by direct metal insertion of simple and readily available primary amides. The overall strategy by N,N-di-Boc activation/metal insertion is suitable for a broad range of coupling protocols via acylmetals. Mechanistic experiments suggest high reactivity of N,N-di-Boc activated 1° amides in direct amide C-N cross-couplings.
- Shi, Shicheng,Szostak, Michal
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supporting information
p. 5872 - 5875
(2016/11/29)
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- Pincer-Nickel-Catalyzed Allyl-Aryl Coupling between Allyl Methyl Ethers and Arylzinc Chlorides
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The P,N,N-pincer nickel complex [Ni(Cl){N(2-Ph2PC6H4)(2′-Me2NC6H4)}]-catalyzed allyl-aryl coupling was studied. The reaction of allyl methyl ethers, including (1-methoxyallyl)arenes and (3-methoxyprop-1-en-1-yl)arenes, with arylzinc chlorides afforded linear (E)-alkenes in high yields, whereas the reaction of (E)-1-methoxytridec-2-ene with p-Me2NC6H4ZnCl generated a mixture of linear and branched alkenes.
- Tao, Jian-Long,Yang, Bo,Wang, Zhong-Xia
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p. 12627 - 12634
(2016/01/09)
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- Ligand-Free Copper-Catalyzed Negishi Coupling of Alkyl-, Aryl-, and Alkynylzinc Reagents with Heteroaryl Iodides
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Reported herein is an unprecedented ligand-free copper-catalyzed cross-coupling of alkyl-, aryl-, and alkynylzinc reagents with heteroaryl iodides. The reaction proceeds at room temperature for the coupling of primary, secondary, and tertiary alkylzinc reagents with heteroaryl iodides without rearrangement. An elevated temperature (100 C) is required for aryl-heteroaryl and alkynyl-heteroaryl couplings.
- Thapa, Surendra,Kafle, Arjun,Gurung, Santosh K.,Montoya, Adam,Riedel, Patrick,Giri, Ramesh
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supporting information
p. 8236 - 8240
(2015/07/07)
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- Pincer-Nickel-Catalyzed Cross-Coupling of Aryl Sulfamates with Arylzinc Chlorides
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The nickel N,N,N-pincer complex 2 was demonstrated to effectively catalyze the cross-coupling of aryl sulfamates with arylzinc chlorides under mild conditions. The reaction is suitable for a wide range of substrates, and tolerates various functional groups. A nickel N,N,N-pincer complex effectively catalyzes the cross-coupling of aryl sulfamates with arylzinc chlorides under mild conditions. The reaction is suitable for a wide range of substrates, and tolerates various functional groups.
- Tao, Jian-Long,Wang, Zhong-Xia
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p. 6534 - 6540
(2015/10/19)
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- Expedient Preparation of Aryllithium and Arylzinc Reagents from Aryl Chlorides Using Lithium 4,4′-Di- tert -Butylbiphenylide and Zinc(II) Chloride
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We report an efficient method for the preparation of aryllithium and zinc reagents from inexpensive and readily available aryl chlorides by using lithium 4,4′-di-tert-butylbiphenylide (LiDBB) as a lithiation reagent. The resulting organometallic reagents underwent subsequent reactions with a variety of electrophiles, such as an aldehydes, DMF, PhSSO2Ph, TsCN, an aryl halide, or an acid chloride (through Pd-catalyzed cross-coupling). Aryl chlorides bearing substituents, including methoxy, 3,4-methylenedioxy, fluoride, TMS, OTMS, NMe2, acetal, and ketal, were shown to be appropriate substrates. Interestingly, aryl chlorides containing a formyl group could also be used, provided that the formyl group was temporarily converted into an α-amino alkoxide by using the lithium amide of N,N,N′-trimethylethylenediamine (LiTMDA). The presence of a hydroxyl group was also tolerated when it was deprotonated with n-BuLi prior to the addition of LiDBB.
- Shen, Zhi-Liang,Sommer, Korbinian,Knochel, Paul
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p. 2617 - 2630
(2015/09/01)
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- Stereoconvergent negishi arylations of racemic secondary alkyl electrophiles: Differentiating between a CF3 and an alkyl group
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In this report, we establish that a readily available nickel/bis(oxazoline) catalyst accomplishes a wide array of enantioconvergent cross-couplings of arylzinc reagents with CF3-substituted racemic secondary alkyl halides, a process that necessitates that the chiral catalyst be able to effectively distinguish between a CF3 and an alkyl group in order to provide good ee. We further demonstrate that this method can be applied without modification to the catalytic asymmetric synthesis of other families of fluorinated organic compounds.
- Liang, Yufan,Fu, Gregory C.
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supporting information
p. 9523 - 9526
(2015/08/18)
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- Reactivity of mixed organozinc and mixed organocopper reagents: 11. Nickel-catalyzed atom-economic aryl-allyl coupling of mixed (n-alkyl)(aryl)zincs
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Group selectivity in the allylation of mixed (n-butyl)(phenyl)zinc reagent can be controlled by changing reaction parameters. CuCN-catalyzed allylation in tetrahydrofuran (THF)-hexamethylphosphoric triamide is n-butyl selective and also γ-selective in the presence of MgCl2, whereas CuI-catalyzed allylation in THF in the presence of n-Bu3P takes place with a n-butyl transfer:phenyl transfer ratio of 23:77 and an α:γ transfer ratio of phenyl of 76:24. NiCl2(Ph3P) 2-catalyzed allylation in the presence of LiCl is phenyl selective with an α:γ ratio of 65:35. The reaction of methyl- or n-butyl(aryl)zinc reagents with an allylic electrophile in THF at room temperature in the presence of NiCl2(Ph3P)2 catalyst and LiCl as an additive provides an atom-economic alternative to aryl-allyl coupling using diarylzincs. Copyright
- Kalkan, Melike
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p. 725 - 732
(2014/11/08)
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- Mono- and dinuclear pincer nickel catalyzed activation and transformation of C-Cl, C-N, and C-O bonds
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Condensation of 2-NH2C6H4P(Et)Ph (2) with pyrrole-2-carboxaldehyde generated 2-(C4H4N-2′-CH - N)C6H4P(Et)Ph (3). Treatment of 3 with NaH and followed by (DME)NiX2 (X = Cl, Br) afforded mononuclear pincer nickel complexes [Ni{2-(C4H3N-2′-CH - N)C6H4P(Et)Ph}X] (4a, X = Cl; 4b, X = Br). Reaction of [2-NH2C6H4P(Ph)]2(CH2)n (5a, n = 3; 5b, n = 4) with pyrrole-2-carboxaldehyde or 5-tert-butyl-1H-pyrrole-2-carbaldehyde formed [2-(C4H4N-2′-CH - N)C6H4P(Ph)]2(CH2)n (6a, n = 3; 6b, n = 4) and [2-(5′-tBuC4H3N-2′-CH - N)C6H4P(Ph)]2(CH2)4 (6c). Respective treatment of 6a-c with NaH followed by (DME)NiX2 (X = Cl, Br) gave the dinuclear nickel complexes [Ni{2-(5′-RC4H2N-2′-CH - N)C6H4P(Ph)}X]2(CH2)n (7a, R = H, X = Cl, n = 3; 7b, R = H, X = Cl, n = 4; 7c, R = H, X = Br, n = 4; 7d, R = tBu, X = Cl, n = 4). Catalysis of the complexes for the activation and transformation of C-Cl, C-N, and C-O bonds was evaluated. Complex 7c exhibited excellent catalytic activity in the cross-coupling of aryl chlorides or aryltrimethylammonium iodides with arylzinc reagents as well as of aryl sulfamates with aryl Grignard reagents. The dinuclear nickel complexes 7b-d showed higher catalytic activity than the mononuclear complexes in each type of reaction.
- Yang, Xia,Wang, Zhong-Xia
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p. 5863 - 5873
(2015/01/09)
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- Efficient access to 3-substituted-γ-hydroxylactams: The uncatalyzed addition of diorganozinc reagents to cyclic imides with heterocyclic substitution
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A range of 3-substituted-γ-hydroxylactams have been prepared via the uncatalyzed addition of organozinc nucleophiles to cyclic imides. This reactivity is primarily limited to imides containing heterocyclic N-substitution, but proceeds efficiently with a variety of diorganozinc reagents, including those prepared and utilized without purification, as well as organozinc halides. It is hypothesized that the presence of a Lewis basic directing group is required for optimum reactivity.
- Deglopper, Kimberly S.,Dennis, Joseph M.,Johnson, Jeffrey B.
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supporting information
p. 1843 - 1845
(2014/03/21)
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- Coordination networks based on nitrile-functionalized borate anions
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Salts of cyano borates bear potential of forming coordination polymers with solvent-filled voids as a source for porous materials. Herein we describe the synthesis and properties of novel cyano borates Na[H-B(O-C12H 8-CN)3], Na[B(O-C12H8-CN) 4] (C12H8 = biphenyl) and Na[B{O-C 6H3-(CN)2}4], as well as a new modification of Na[B(O-C6H4-CN)4]. Crystal structures of the sodium borates and the starting materials HO-C 6H3-(CN)2 and HO-C12H8-CN (new modification) are discussed as well. Data of nitrogen sorption experiments revealed a notable surface area in solvent-free Na[H-B(O-C12H 8-CN)3]. Copyright
- Harloff, Joerg,Karsch, Markus,Lund, Henrik,Schulz, Axel,Villinger, Alexander
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supporting information
p. 1330 - 1341
(2014/07/07)
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- Quantitative kinetic investigation on transmetalation of ArZnX in a Pd-catalysed oxidative coupling
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Transmetalation is the rate-limiting step. [R-Pd-Ar] was suggested to be the resting species from the kinetic studies. Quantitative measurement of the transmetalation of ArZnCl with [R-Pd-Ar] from a live Pd-catalysed oxidative coupling reaction was conducted and the corresponding activation enthalpy was determined as 12.3 kcal mol-1. The Royal Society of Chemistry 2013.
- Li, Jing,Jin, Liqun,Liu, Chao,Lei, Aiwen
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p. 9615 - 9617
(2013/10/08)
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- Synthesis of α-amino amides via N,O-acetals derived from Weinreb amides
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(Chemical Equation Presented) An easy and straightforward synthesis of α-amino amides via a base-mediated rearrangement of modified Weinreb amides into N,O-acetals is presented. Subsequent arylation, alkylation, alkenylation, or alkynylation of this intermediate affords the corresponding R-amino amides in excellent yields. Furthermore, a more generalized protocol for the α-arylation of Weinreb amides lacking an R-amino moiety is also discussed.
- Hirner, Sebastian,Somfai, Peter
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experimental part
p. 7798 - 7803
(2009/12/29)
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- COMPOUNDS AND METHODS FOR TREATING PROTEIN FOLDING DISORDERS
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The invention is directed to compounds and methods for treating protein folder disorders. In certain embodiments the invention provides compounds and methods for treating neurodegenerative diseases such as Alzheimer's disease, tauopathy, cerebral amyloid angiopathy, Lewy body disease, dementia, Huntington's disease and prion-based spongiform encelopathy. The invention further provides compounds, methods and pharmaceutical compositions for inhibiting tau protein, Aβ protein or α-synuclein protein aggregation.
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Page/Page column 105-106
(2008/12/05)
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- Efficient palladium-catalyzed synthesis of unsymmetrical donor-acceptor biaryls and polyaryls
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4,4'-Unsymmetrically substituted biphenyls can be synthesized by cross-coupling reactions of substituted aromatic organometallic reagents and aromatic halides catalyzed by palladium complexes.This two-step method from commercially available aromatic halides has been used for the synthesis of a series of donor/acceptor para-substituted biphenyls, D-C6H4-C6H4-A, where D is an electron donor group and A an electron acceptor group, which are of interst as liquid crystal precursors and as having potential in non-linear optics.Biaryls in which the donor-phenyl moiety is replaced by a 2-furyl or 2-thienyl can be synthesized similarly.The method can also be used for the convergent synthesis of previously unreported unsymmetrically substituted polyparaphenylenes D-(C6H4)n-A (n = 3, 4).
- Amatore, Christian,Jutand, Anny,Negri, Serge,Fauvarque, Jean-Francois
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p. 389 - 398
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF 5-ARYLTROPONES
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2-methoxy-5-oxy>tropone was coupled to a variety of arylzinc chlorides in the presence of a palladium catalyst to furnish 5-aryltropones in good to excelent yields.
- Keenan, Richard M.,Kruse, Lawrence I.
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p. 793 - 798
(2007/10/02)
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- Conversion of Stilbene to trisubstituted Olefins
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Determination of stereochemistry of bromination-dehydrobromination of both cis and trans-stilbene has been achieved.Coupling of the resulting vinyl bromides with alkyl or aryl groups have been done.The coupling products could serve as intermediates for the synthesis of biologically active tetrasubstituted olefins.
- Al-Hassan, Mohammed I.
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p. 463 - 472
(2007/10/02)
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