- Gold-Catalyzed C(sp2)?C(sp) Coupling by Alkynylation through Oxidative Addition of Bromoalkynes
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A gold(I)-catalyzed cascade cyclization–alkynylation of allenoates using alkynyl bromide to generate β-alkynyl-γ-butenolides was investigated. Whereas alkynyl iodides afforded significant amounts of the homo-coupling of two lactone units, alkynyl bromides led to a selective reaction, and a broad functional group tolerance was observed. Under the optimized reaction conditions, it was possible to directly synthesize a large range of β-alkynyl-γ-butenolides in moderate to good yields without the need for any external oxidant.
- Yang, Yangyang,Schie?l, Jasmin,Zallouz, Sirine,G?ker, Verena,Gross, Jürgen,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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- Regio- and Stereoselective N-addition to an Open Bromo Vinyl Cation
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A protocol for the synthesis of thus far inaccessible bromo vinyl triflimides is presented. Our previously reported concept of assisted vinyl cation formation was engaged to achieve both a protonation of relatively electron poor bromo alkynes and a reaction with high regio- and stereoselectivity. To the best of our knowledge, this is the first stereoselective addition of an N-nucleophile to an open β-halovinyl cation.
- Chuchmareva, Marina,Collong, Arndt,Niggemann, Meike,Schr?der, Sebastian,Strauch, Christina
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- Facile and efficient synthesis of 1-haloalkynes via DBU-mediated reaction of terminal alkynes and N-haloimides under mild conditions
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Directly from terminal alkynes and with N-halosuccinimides (halo = Br and I) or N-cholorophthalimide as the halogen sources, DBU as the activator, 1-haloalkynes were prepared in good to excellent yields at room temperature. Bis(bromoalkyne) and bis(iodoal
- Li, Mengru,Li, Yueju,Zhao, Baozhong,Liang, Fushun,Jin, Long-Yi
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- Catalytic Synthesis of Dibenzazepines and Dibenzazocines by 7-Exo- and 8-Endo-Dig-Selective Cycloisomerization
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The 7-exo- and 8-endo-dig-selective gold-catalyzed cycloisomerizations of 2-propargylamino biphenyl derivatives were developed. The reaction of terminal alkynes gave dibenzo[b,d]azepines by 7-exo-dig cycloisomerization. In contrast, when internal alkynes were subjected to the reaction, 8-endo-dig cycloisomerization proceeded to provide dibenzo[b,d]azocines. The nucleophilicity at the reaction site and the electron-withdrawing effect of a tosyl group were important for the present selective transformation. This protocol could be used for ynamide substrates and a silver-catalyzed reaction gave 7-exo-dig products selectively.
- Ito, Mamoru,Takaki, Asahi,Okamura, Moeka,Kanyiva, Kyalo Stephen,Shibata, Takanori
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- Visible-Light-Promoted Formation of C—C and C—P Bonds Derived from Evolution of Bromoalkynes under Additive-Free Conditions: Synthesis of 1,1-Dibromo-1-en-3-ynes and Alkynylphosphine Oxides
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The controllable achievement of C—C and C—P bond formations is developed via visible-light-promoted bromoalkyne dimerization or its further transformation with secondary phosphine oxides. The 1,1-dibromo-1-en-3-ynes are formed when bromoalkyne is exposed to visible-light. While alkynylphosphine oxides are generated when bromoalkynes are mixed with secondary phosphine oxides.
- Xu, Hailong,Chen, Rui,Ruan, Hongjie,Ye, Ruyi,Meng, Ling-Guo
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supporting information
p. 873 - 878
(2021/03/04)
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- Nickel-Catalyzed Difunctionalization of Alkynyl Bromides with Thiosulfonates and N -Arylthio Succinimides: A Convenient Synthesis of 1,2-Thiosulfonylethenes and 1,1-Dithioethenes
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An efficient nickel-catalyzed vicinal thiosulfonylation of 1-bromoalkynes with thiosulfonates in the presence of cesium carbonate is described. An operationally simple and highly regioselective atom transfer radical addition (ATRA) of alkynyl bromides provides a wide range of (E)-1,2-thiosulfonylethenes (α-aryl-β-thioarylvinyl sulfones) in moderate to high yields. The extensive substrate scope of both alkynyl bromides and thiosulfonates is explored with a broad range of functional groups. Indole-derived 1,1-bromoalkenes were also successfully explored in this 1,2-thiosulfonylation process. Moreover, the nickel-catalyzed geminal -dithiolation of alkynyl bromides with N -arylthio succinimides provides 1,1-dithioalkenes in high yields. The present protocol is reliable on gram scale, and a sequential one-pot bromination and thiosulfonylation of phenylacetylene is achieved in a scale-up synthesis. Following control experiments, a plausible mechanism is proposed to rationalize the experimental outcome and the vicinal thio-sulfonylation.
- Kumari, Arram Haritha,Kumar, Jangam Jagadesh,Krishna, Gamidi Rama,Reddy, Raju Jannapu
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supporting information
p. 2850 - 2864
(2021/05/18)
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- Tertiary Enamide-Triggered SEAr: Domino Allylation and Enamine-Type Addition
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Two unprecedented domino reactions are described, starting from ketospiro-enesulfonamides. By treatment with ZrCl4 and allylsilane, an intramolecular electrophilic aromatic substitution and subsequent allylation is observed. By treatment with TiCl4 and allylsilane, a double enamine-type reaction takes place, thus creating simultaneously four contiguous stereogenic centers diastereoselectively.
- Beltran, Frédéric,Miesch, Laurence
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supporting information
p. 1569 - 1573
(2019/03/12)
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- Gold Catalyzed Photoredox C1-Alkynylation of N-Alkyl-1,2,3,4- tetrahydroisoquinolines by 1-Bromoalkynes with UVA LED Light
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A synthetic method that combines [Au2(m-dppm)2]Cl2 (dppm=bis(diphenylphosphanyl)methane) and UVA LED (LED=light emitting diode) light (365 nm) to catalyze the regioselective C1-alkynylation of N-alkyl-1,2,3,4-tetrahydroisoquinolines (THIQs) with alkynyl bromides is described. The reaction mechanism was delineated to involve a reductive quench pathway to generate the two posited radical species of the nitrogen-containing heterocycle and organic halide. In contrast, radical formation via an oxidative quench pathway was suggested to be operative in analogous control experiments with a 1-iodoalkyne. The usefulness of this carbon-carbon bond forming strategy was also exemplified by its application to the formal synthesis of the opioid analgesic drug methopholine and synthesis of a protoberberine alkaloid derivative.
- Zhao, Yichao,Jin, Jianwen,Chan, Philip Wai Hong
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supporting information
p. 1313 - 1321
(2019/06/03)
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- Nickel-Catalyzed Reductive 1,2-Dialkynylation of Alkenes Bearing an 8-Aminoquinoline Directing Group
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An unprecedented nickel-catalyzed reductive 1,2-dialkynylation of alkenes bearing an 8-aminoquinoline directing group has been developed. This method proceeded through a migratory insertion/reductive-coupling process under mild conditions with a wide substrate scope and good functional group tolerance, providing direct access to the synthetically flexible 1,5-diynes. Moreover, the 1,2-dialkynylation products could be further converted to borate-ester- or azide-functionalized 1,5-dienes, ditriazole, β-diyne primary amide, and trisubstituted benzene.
- Pan, Rui,Shi, Cong,Zhang, Dongquan,Tian, Yang,Guo, Songjin,Yao, Hequan,Lin, Aijun
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supporting information
p. 8915 - 8920
(2019/11/14)
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- A Highly Regio- and Stereoselective Syntheses of α-Halo Enamides, Vinyl Thioethers, and Vinyl Ethers with Aqueous Hydrogen Halide in Two-Phase Systems
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A metal-free regio- and stereoselective method is achieved for the preparation of (E)-configured α-halo enamides, vinyl thioethers, and vinyl ethers using aqueous HX (X = F, Cl, Br, I), which features high functional group compatibility and regio- and stereoselectivity, mild conditions, high efficiency, and rapid transformation. Additionally, the isomers could be yielded readily from the (E)-configured α-halo enamides via photocatalysis or under Sonogashira coupling conditions.
- Cao, Wei,Chen, Ping,Wang, Liang,Wen, Hao,Liu, Yu,Wang, Wanshu,Tang, Yu
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supporting information
p. 4507 - 4511
(2018/08/09)
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- Dual Gold-Catalyzed Formal Tetradehydro-Diels–Alder Reactions for the Synthesis of Carbazoles and Indolines
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This work reports a dual gold-catalyzed tetradehydro-Diels–Alder reaction for the synthesis of nitrogen-containing aromatic heterocycles. Under the catalytic system (IPrAuNTf2/DIPEA), indolines and carbazoles as well as other N-containing aromatic heterocycles were prepared in high yields with good functional group tolerance. Unlike the traditional thermal tetradehydro-Diels–Alder reactions, diluted reaction concentration and radical prohibitors are not required for this protocol. Experimental data support a mechanism involving gold vinylidene species, which undergoes a 6 π electrocyclization, followed with 1,2-hydrogen shift.
- Wang, Hong-Fa,Wang, Shi-Yue,Qin, Tian-Zhu,Zi, Weiwei
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supporting information
p. 17911 - 17914
(2018/11/23)
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- α-Imino Gold Carbenes from 1,2,4-Oxadiazoles: Atom-Economical Access to Fully Substituted 4-Aminoimidazoles
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A novel and atom-economical synthesis of fully substituted 4-aminoimidazoles via gold-catalyzed selective [3 + 2] annulation of 1,2,4-oxadiazoles with ynamides is reported. This protocol represents a new strategy to access α-imino gold carbenes, which corresponds to an unprecedented intermolecular transfer of N-acylimino nitrenes to ynamides. Moreover, the reaction proceeds with 100% atom economy, exhibits good functional group tolerance, and can be conducted in gram scale.
- Zeng, Zhongyi,Jin, Hongming,Xie, Jin,Tian, Bing,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 1020 - 1023
(2017/03/15)
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- Csp-Csp3 Bond Formation via Iron(III)-Promoted Hydroalkynylation of Unactivated Alkenes
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An iron(III)-promoted hydroalkynylation of unactivated alkenes toward Csp-Csp3 bond formation has been developed. Various alkenes, including mono-, di-, and trisubstituted alkenes, could all smoothly convert to structural diversified alkynes in this chemoselective protocol. Additionally, the scalability was unraveled and the further divergent transformations of products were conducted to demonstrate the synthetic utility.
- Shen, Yangyong,Huang, Bo,Zheng, Jing,Lin, Chen,Liu, Yu,Cui, Sunliang
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supporting information
p. 1744 - 1747
(2017/04/11)
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- Regioselective TfOH-mediated hydroamidation of ynamides with nitriles
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A new TfOH-mediated reaction of ynamides with nitriles as nucleophiles has been developed. The reaction works efficiently under mild reaction conditions to afford a new class of α-acylaminoenamides readily via the intermediacy of keteniminium ion. The reaction displays generality and a broad substrates scope. Additionally, the α-acylaminoenamides could be transformed to highly substituted pyridine, 4-aminopyrimidine or isoquinoline cores.
- Wang, Wan-Shu,Chen, Ping,Tang, Yu
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p. 2731 - 2739
(2017/04/14)
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- Borane-catalyzed selective hydrosilylation of internal ynamides leading to β-silyl (Z)-enamides
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We have developed a borane-catalyzed regioand stereoselective hydrosilylation of internal ynamides for the first time. The scope of ynamide substrates and silane reactants was broad under mild reaction conditions, affording synthetically versatile β-silyl (Z)-enamide products. The observed stereoselectivity was reasoned to be due to the β-silicon effect on a postulated ketene iminium intermediate.
- Kim, Youngchan,Dateer, Ramesh B.,Chang, Sukbok
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supporting information
p. 190 - 193
(2017/11/27)
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- Gold-Catalyzed Intermolecular Nitrene Transfer from 2H-Azirines to Ynamides: A Direct Approach to Polysubstituted Pyrroles
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(Chemical Equation Presented). An effective gold-catalyzed intermolecular nitrene transfer by the reaction of 2H-azirines and ynamides is reported, which provides highly substituted pyrroles in a straightforward manner. This transformation proceeds under mild conditions and gives the polysubstituted pyrroles in good-to-excellent yields. Preliminary results indicate that a nongold carbenoid pathway is preferred for current pyrrole synthesis.
- Zhu, Lei,Yu, Yinghua,Mao, Zhifeng,Huang, Xueliang
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supporting information
p. 30 - 33
(2015/07/28)
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- Rapid access to unsymmetrical 1,3-diynes and 2,5-disubstituted thiophenes under ligand and Pd/Ni-free Cu-catalysis
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A Pd/Ni-free copper-catalysed tandem synthesis was realized for rapid access to unsymmetrical 1,3-diynes from 1,1-dibromoalkenes and terminal alkynes. This method was extended to the straightforward synthesis of unsymmetrical 2,5-disubstituted thiophenes
- Rao, Maddali L. N.,Islam, Sk Shamim,Dasgupta, Priyabrata
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p. 78090 - 78098
(2015/09/28)
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- Copper-catalyzed N-alkynylations of sulfoximines with bromoacetylenes
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N-Alkynylated sulfoximines have been obtained by copper-catalyzed cross-coupling reactions starting from NH-sulfoximines and bromoacetylenes in moderate to good yields. The reaction conditions are mild, and the substrate scope is wide.
- Chen, Xiao Yun,Wang, Long,Frings, Marcus,Bolm, Carsten
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supporting information
p. 3796 - 3799
(2014/08/05)
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- Palladium-catalyzed alkynylative lactonization of unsaturated bicyclic carboxylic acids: Synthesis of fused polycyclic γ-lactone compounds
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Unsaturated bicyclic carboxylic acids undergo palladium-catalyzed coupling with bromoalkynes to produce γ-alkynyl lactones in moderate to good yields with excellent chemo- and regioselectivity. The reaction conditions were extremely mild, and functional groups such as methyl, methoxy, chloro, and bromo were tolerated under the optimized reaction conditions. Moreover, γ-chloroalkenyl lactones were facilely synthesized through chloropalladation/carboesterification of electron-deficient C≡C bonds by using molecular oxygen as the sole oxidant. Facile and tandem Pd-catalyzed synthesis of γ-alkynyl lactone and γ-chloroalkenyl lactone derivatives by using readily accessible bromoalkynes and unsaturated bicyclic carboxylic acids is reported. Two subsequent steps, namely, C(sp or sp 2)-C(sp3) bond formation and C-O bond formation, are catalyzed by a single Pd catalyst. The reactions proceed with good yields of the products. Copyright
- Sun, Ning,Li, Yibiao,Yin, Gengming,Jiang, Shaohua
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supporting information
p. 2541 - 2544
(2013/06/04)
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- Synthesis of N-alkyl-substituted 4-quinolones via tandem alkenyl and aryl C-N bond formation
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N-Alkyl-substituted 4-quinolones are present as the key structural motif in many marketed drugs. An efficient one-step tandem amination approach was developed to afford N-alkyl-substituted 4-quinolones in high yields from easily accessible o-chloroaryl acetylenic ketones and functionalized alkyl amines. The approach complements and extends our previous work. Compared with other reported methods, the current method provides a very simple and convenient route. Georg Thieme Verlag Stuttgart · New York.
- Shao, Jun,Huang, Xiaomei,Hong, Xiaohu,Liu, Bingxin,Xu, Bin
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experimental part
p. 1798 - 1808
(2012/08/08)
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- Palladium-catalyzed bromoalkynylation of C-C double bonds: Ring-structure-dependent synthesis of 7-alkynyl norbornanes and cyclobutenyl halides
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Strain versus flexibility: The palladium-catalyzed reaction of haloalkynes with norbornene derivatives leads to 7-alkynyl norbornane products (see scheme). Key to the success of this reaction is the formation of a "bridging" palladium species, which can rearrange to result in a C-7 functionalization. The ring-structure-dependent [2+2] cycloaddition of haloalkynes with cyclooctene has been achieved in moderate to good yields under similar conditions. Copyright
- Li, Yibiao,Liu, Xiaohang,Jiang, Huanfeng,Liu, Bifu,Chen, Zhengwang,Zhou, Peng
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supporting information; experimental part
p. 6341 - 6345
(2011/09/13)
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- A sequential metal-catalyzed C-N bond formation in the synthesis of 2-amido-indoles
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(Chemical Equation Presented) A sequential metal-catalyzed C-N bond formation employing ortho-haloaryl acetylenic bromides is described. The initial amidation is highly selective for C8P-N bond formation, leading to o-haloaryl-substiluted ynami
- Yao, Pei-Yuan,Zhang, Yu,Hsung, Richard P.,Zhao, Kang
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supporting information; experimental part
p. 4275 - 4278
(2009/05/30)
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