- Formal total synthesis of selaginpulvilin D
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An efficient and mild synthetic strategy for the total synthesis of selaginpulvilin D has been reported. A highly chemoselective enyne-alkyne dehydro Diels-Alder reaction has been employed for the construction of the tricyclic fluorene framework present i
- Chinta, Bhavani Shankar,Baire, Beeraiah
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- Copper-catalyzed domino synthesis of ynamines
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The hitherto unexploredN-alkynylation of electron-withdrawing or protecting group free N-heteroarenes such as indole, carbazole and pyrrole was developed usinggem-dibromoalkenes to synthesize ynamines under ligand-free copper-catalyzed domino conditions. The development methodology of ynamines was also applied in the synthesis of enynamines, multi-coupled bis-ynamines, tris-ynamines, and the natural product peyonine, demonstrating its broad synthetic scope and applications.
- Dasgupta, Priyabrata,Islam, Sk Shamim,Rao, Maddali L. N.
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p. 7855 - 7860
(2021/09/28)
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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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p. 2850 - 2864
(2021/05/18)
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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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supporting information
(2021/06/07)
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- Catalytic Cyclotrimerization Pathway for Synthesis of Selaginpulvilins C and D: Scope and Limitations
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A facile and unified approach to the main selaginpulvilin's framework was achieved by catalytic [2 + 2 + 2]-cyclotrimerization of a triyne with monosubtituted alkynes. The reaction proceeded with high "ortho"selectivity by using Wilkinson's catalyst (RhCl
- Rycek, Lukas,Mateus, Miguel,Beytlerová, Nela,Kotora, Martin
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supporting information
p. 4511 - 4515
(2021/04/12)
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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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- Copper-Catalyzed Perfluoroalkylation of Alkynyl Bromides and Terminal Alkynes
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A copper-catalyzed one-pot perfluoroalkylation of alkynyl bromides and terminal alkynes has been disclosed, and the corresponding perfluoroalkylated alkynes could be attained in good to excellent yields. The new straightforward transformation shows high efficiency (0.01-0.5 mol % catalyst loading), broad substrate scope, and remarkable functional group tolerance and provides a facile approach for useful application in life and material sciences.
- Fan, Shilu,Zheng, Chenggong,Zheng, Kaiting,Li, Junlan,Liu, Yaomei,Yan, Fangpei,Xiao, Hua,Feng, Yi-Si,Zhu, Yuan-Yuan
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supporting information
p. 3190 - 3194
(2021/05/05)
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- Palladium-Catalyzed Carbonylation in the Synthesis of N-Ynonylsulfoximines
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Palladium-catalyzed carbonylation reactions with Cr(CO)6 as carbonyl source are key for the preparation of N-ynonylsulfoximines from NH-sulfoximines and bromoalkynes. The couplings proceed at room temperature with a wide range of substrate combinations affording the corresponding products in good yields. (Figure presented.).
- Ma, Ding,Wang, Chenyang,Kong, Deshen,Tu, Yongliang,Shi, Peng,Bolm, Carsten
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supporting information
p. 1330 - 1334
(2021/01/26)
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- A Unified Approach for Divergent Synthesis of Heterocycles via TMSOTf-Catalyzed Formal [3+2] Cycloaddition of Electron-Rich Alkynes
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We present a synthetic protocol for the construction of polysubstituted five-membered heterocycles via TMSOTf-catalyzed formal [3+2] cycloaddition of electron-rich alkynes, which features free from any metal, atom economy and water as the main by-product. Furthermore, alkenyl ether adduct has been verified as the key intermediate. Notably, by utilizing this approach, we can synthesize a broad range of polysubstituted furans, thiophenes and pyrroles, and extend this transformation to deliver fused-polyheterocycles. This reaction can be achieved on a gram scale and the corresponding products are intermediates for producing diverse potentially useful scaffolds. (Figure presented.).
- Chen, Ping,Cao, Wei,Li, Xiangqian,Shi, Dayong
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supporting information
p. 4789 - 4794
(2021/09/02)
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- A Radical-Initiated Fragmentary Rearrangement Cascade of Ene-Ynamides to [1,2]-Annulated Indoles via Site-Selective Cyclization
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Straightforward access to [1,2]-annulated indoles, key substructures in natural products, is highly desirable yet challenging. Herein, a radical triggered fragmentary cyclization cascade reaction of ene-ynamides is presented, providing a rapid access into [1,2]-annulated indoles by an intermolecular radical addition, intramolecular cyclization, desulfonylative aryl migration, and site-selective C(sp2)-N cyclization sequence. DFT calculations support oxidation of N-centered radical species to cations prior to the C-N bond formation, followed by an unusual aza-Nazarov cyclization.
- Li, Sifan,Wang, Yu,Wu, Zibo,Shi, Weiliang,Lei, Yibo,Davies, Paul W.,Shu, Wei
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p. 7209 - 7214
(2021/09/14)
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- Total Synthesis of Dictyodendrins A–F by the Gold-Catalyzed Cascade Cyclization of Conjugated Diyne with Pyrrole
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The total synthesis of dictyodendrins A–F was achieved by using the gold(I)-catalyzed annulation of a conjugated diyne with N-Boc-pyrrole for direct construction of the pyrrolo[2,3-c]carbazole scaffold. Late-stage functionalization of the resulting pyrrolo[2,3-c]carbazole to introduce various substituents provided divergent access to dictyodendrins. Some dictyodendrin analogues exhibited inhibitory activities toward CDK2/CycA2 and GSK3.
- Inuki, Shinsuke,Matsuda, Yuka,Matsuoka, Junpei,Miyamoto, Yoichi,Ohno, Hiroaki,Oishi, Shinya,Oka, Masahiro,Otani, Mayumi
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- Chemo- And regioselective click reactions through nickel-catalyzed azide-alkyne cycloaddition
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Metal-catalyzed cycloaddition is an expeditious synthetic route to functionalized heterocyclic frameworks. However, achieving reactivity-controlled metal-catalyzed azide-alkyne cycloadditions from competing internal alkynes has been challenging. Herein, we report a nickel-catalyzed [3 + 2] cycloaddition of unsymmetrical alkynes with organic azides to afford functionalized 1,2,3-triazoles with excellent regio- and chemoselectivity control. Terminal alkynes and cyanoalkynes afford 1,5-disubstituted triazoles and 1,4,5-trisubstituted triazoles bearing a 4-cyano substituent, respectively. Thioalkynes and ynamides exhibit inverse regioselectivity compared with terminal alkynes and cyanoalkynes, affording 1,4,5-trisubstituted triazoles with 5-thiol and 5-amide substituents, respectively. Density functional theory calculations are performed for the elucidation of the reaction mechanism. The computed mechanism suggests that a nickellacyclopropene intermediate is generated by the oxidative addition of the alkyne substrate to the Ni(0)-Xantphos catalyst, and the subsequent C-N coupling of this intermediate with an azide is responsible for the chemo- and regioselectivity.
- Baek, Seung-Yeol,Baik, Mu-Hyun,Choe, Wonyoung,Hong, Sung You,Jeon, Ji Hwan,Jeong, Seo Yeong,Kim, Woo Gyum,Nam, Dongsik
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supporting information
p. 3374 - 3381
(2020/05/14)
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- Visible-Light-Promoted Oxo-Sulfonylation of Ynamides with Sulfonic Acids
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A visible-light-promoted oxo-sulfonylation of ynamides with sulfonic acids is reported, giving rise to a collection of functionalized α-sulfonylated amides in a straightforward manner. The reaction proceeds sequentially through a cascade of electrophilic addition and photoinduced sulfonyl radical-sustained skeleton rearrangement. The high atom economy, mild reaction conditions, and wide substrate scope comprised the merits of this synthetic transformation.
- Wang, Lu,Lu, Chengrong,Yue, Yanni,Feng, Chao
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p. 3514 - 3517
(2019/05/16)
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- 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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supporting information
p. 9624 - 9628
(2019/07/05)
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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 Micellar Catalysis Strategy for Amidation of Alkynyl Bromides: Synthesis of Ynamides in Water
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Copper-catalyzed amidation of alkynyl bromides can be carried out in water for the first time, which is made possible by a micellar catalysis strategy using rosin-based surfactant APGS-550-M. The surfactant can be easily prepared from natural abundant biomass, resin acids. Studies as to substrate scope and reaction aqueous medium recycling showcase the ease and sustainability of this technology.
- Yang, Yunqin,Meng, Xiangtai,Zhu, Baolong,Jia, Ying,Cao, Xiaoji,Huang, Shenlin
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supporting information
p. 1166 - 1169
(2019/01/04)
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- Copper-catalyzed one-pot synthesis of alkynylphophonates
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Copper is found to be an effective catalyst for the preparation of alkynylphophonates. A novel copper-catalyzed one-pot synthesis of alkynylphophonates from terminal alkynes and dialkyl phosphites is developed which involves the haloalkynes intermediates. This method provides a unique and alternative approach to the well-documented oxidative coupling or arylpropiolic acid strategies.
- Song, Wang-Ze,Li, Jun-Hao,Li, Ming,He, Jun-Nan,Dong, Kun,Ullah, Karim,Zheng, Yu-Bin
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supporting information
p. 697 - 703
(2019/02/16)
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- Synthesis of fluoroalkylated alkynes: Via visible-light photocatalysis
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Fluoroalkylated alkynes, which are versatile building blocks for the synthesis of various biologically active organofluorine compounds, were synthesized from easily available alkynyl halides and fluoroalkyl halides by visible-light photocatalysis. Addition of fluoroalkyl radicals to alkynes and subsequent dehalogenation selectively yielded fluoroalkylated alkynes.
- Iqbal, Naila,Iqbal, Naeem,Han, Sung Su,Cho, Eun Jin
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supporting information
p. 1758 - 1762
(2019/02/20)
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- A convenient route to 1,3-diynes using ligand-free Cadiot–Chodkiewicz coupling reaction at room temperature under aerobic conditions
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In this study, we report a copper-catalyzed ligand-free Cadiot–Chodkiewicz coupling reaction. No additives or ligands are required for this Cu-catalyzed C(sp)–C(sp) coupling reaction of terminal alkynes with alkynyl halides. The low cost of copper catalyst, excellent yield of the products, suppression of side-products and mild reaction conditions are the major advantages of this protocol.
- Asha, Sujatha,Anjana, Sasidharan,Thomas, Anns Maria,Thomas, Minu Elizabeth,Rohit,Krishnan, K. Keerthi,Ujwaldev, Sankuviruthiyil M,Anilkumar, Gopinathan
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supporting information
p. 256 - 265
(2019/01/24)
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- Visible Light-Induced Difunctionalization of Alkynes: The Synthesis of Thiazoles and 1,1-Dibromo-1-en-3-ynes
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A visible light-induced cascade cyclization of thioamides with alkynes was developed to synthesize 1,3-thiozoles. The sulfur radical generated from thioamide via the single-electron transfer (SET) pathway was promoted by photocatalysis as a key intermediate in this reaction. When bromoalkynes were used as the substrate, the self-coupling products 1,1-dibromo-1-en-3-ynes were obtained in moderate yields, and an energy transfer pathway for this transformation promoted by visible-light photocatalysis was proposed.
- Huang, Xiaoying,Chen, Hui,Huang, Zhongzhi,Xu, Yanli,Li, Fangyao,Ma, Xianli,Chen, Yanyan
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p. 15283 - 15293
(2019/12/04)
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- TsNBr2 promoted decarboxylative bromination of α,β-unsaturated carboxylic acids
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A rapid process for decarboxylative bromination of α,β-unsaturated carboxylic acids have been developed using N,N-dibromo-p-toluenesulfonamide (TsNBr2). Treatment of cinnamic acids with TsNBr2 in presence of potassium carbonate in acetonitrile produces corresponding β-bromostyrenes at room temperature. Exclusive formation of (E)-β-bromostyrenes was observed in a stereoselective manner within a very short period of time (5–15 min). This method was further extended for obtaining 1-bromoalkynes from corresponding propiolic acids. Instantaneous formation of bromoalkynes was observed when the reaction was carried out in presence of DBU as a base in acetonitrile at room temperature. A wide variety of cinnamic acids and propiolic acids could be converted to corresponding β-bromostyrenes and 1-bromoalkynes respectively under mild reaction condition with high to excellent yield.
- Hazarika, Debojit,Phukan, Prodeep
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supporting information
p. 4593 - 4596
(2018/11/23)
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- Total synthesis of selaginpulvilins A and C
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An efficient formal total synthesis of two compounds from the selaginpulvilin family of natural products, selaginpulvilin A and C, has been successfully achieved. The tetradehydro Diels-Alder (TDDA) reaction between an enyne and alkyne has been utilized for the creation of the necessary fluorene skeleton. Attempts at the conversion of selaginpulvilin A to selaginpulvilin B, F and H were unsuccessful.
- Chinta, Bhavani Shankar,Baire, Beeraiah
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p. 262 - 265
(2018/01/12)
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- Chloramine Salt Mediated Oxidative Halogenation of Terminal Alkynes with KI or NaBr: Practical Synthesis of 1-Bromoalkynes and 1-Iodoalkynes
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A direct oxidative halogenation of terminal alkynes has been realized using chloramine-B as the oxidant and KI or NaBr as the halogen source. This reaction enables a general and practical access to synthetically valuable 1-bromoalkynes and 1-iodoalkynes i
- Liu, Xiaozu,Chen, Guojun,Li, Chenglong,Liu, Peijun
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p. 2051 - 2055
(2018/09/18)
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- Preparation method of 1-bromoalkyne and 1-iodoalkyne
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The invention discloses a preparation method of 1-bromoalkyne and 1-iodoalkyne. The preparation method comprises the following steps that terminal alkyne is adopted as a raw material, a chloramine salt and an iodine salt or a bromine salt is adopted as a
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Paragraph 0044; 0045; 0046
(2018/11/03)
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- First Total Synthesis of Original Chalcone–Flavone Dimers as Cissampeloflavone Analogues
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The total synthesis of furoflavones closely related to the natural product cissampeloflavone was explored following different pathways. The involvement of a flavone as a key intermediate proved to be the most efficient way to form the 7-phenyl-5H-furo[3,2-g]chromen-5-one scaffold, and the first example of furoflavone formation was achieved in this way. For the synthesis of chalcone–flavone dimers, two different strategies were examined: either acylation at the very end of the synthesis, or introduction of the 3-acyl group during furan-ring formation. The final acylation was hardly achievable with hindered benzoyl chlorides, but a simpler 4-methoxybenzoyl group was added to the furoflavone in modest yield. The alternative direct introduction of this acyl group during furan formation proved to be more efficient. Conjugate addition of an iodoflavone to an ynone followed by intramolecular Heck cyclization gave the best results, leading to the first synthetic chalcone–flavone dimer ever described.
- Thévenin, Marion,Thoret, Sylviane,Dubois, Jo?lle
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supporting information
p. 5843 - 5852
(2018/11/24)
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- Gold-Catalyzed Intermolecular [4+2] Annulation of 2-Ethynylanilines with Ynamides: An Access to Substituted 2-Aminoquinolines
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A gold-catalyzed intermolecular [4+2] annulation of easily accessible 2-ethynylanilines with ynamides offers a highly region-selective, modular, efficient, and atom-economical strategy for the synthesis of substituted 2-aminoquinolines in up to 93% yield. (Figure presented.).
- Zhao, Ximei,Song, Xinlong,Jin, Hongming,Zeng, Zhongyi,Wang, Qian,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 2720 - 2726
(2018/07/29)
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- Palladium-Catalyzed Oxygenative Cross-Coupling of Ynamides and Benzyl Bromides by Carbene Migratory Insertion
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A palladium-catalyzed oxygenative cross-coupling of ynamides and benzyl bromides has been developed. After subsequent hydrogenation, α,α-disubstituted amide derivatives were obtained in good yields. Migratory insertion of α-oxo palladium carbene species, generated by intermolecular oxidation, is proposed as the key step in this reaction. The study demonstrates the potential of ynamides to serve as carbene precursors in palladium-catalyzed C?C bond-forming cross-coupling reactions.
- Gao, Yunpeng,Wu, Guojiao,Zhou, Qi,Wang, Jianbo
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supporting information
p. 2716 - 2720
(2018/02/13)
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- Modular synthesis of heptaarylindole
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The first synthesis of heptaarylindole (HAI) has been accomplished using a coupling/ring transformation strategy. Four readily prepared modular units (diarylthiophenes, 2-arylaziridines, arylboronic acids, and arylalkynes) were joined together to provide
- Suzuki, Shin,Asako, Takashi,Itami, Kenichiro,Yamaguchi, Junichiro
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supporting information
p. 3771 - 3776
(2018/05/30)
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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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- Metal-Free [2 + 2 + 2] Cycloaddition of Ynamide-Nitriles with Ynamides: A Highly Regio- and Chemoselective Synthesis of δ-Carboline Derivatives
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A metal-free formal [2 + 2 + 2] cycloaddition of functionalized ynamide-nitriles with ynamides is disclosed which offers highly efficient access to polysubstituted δ-carboline derivatives under the mediation of TfOH. This strategy is highly regioselective and chemoselective and displays mild conditions, high yields, and efficiency (within 1 min) in addition to substrates scopes (56 examples).
- Wen, Hao,Cao, Wei,Liu, Yu,Wang, Liang,Chen, Ping,Tang, Yu
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p. 13308 - 13324
(2018/11/02)
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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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- Synthesis of o-Allyloxy(ethynyl)benzene Derivatives by Cu-Catalyzed Suzuki–Miyaura-Type Reaction and Their Transformations into Heterocyclic Compounds
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We have found that Suzuki–Miyaura-type reactions of o-allyloxy(bromoethynyl)benzenes with arylboronic acids using a hydrazone/Cu catalyst system proceeded smoothly in iPrOH under mild conditions to afford the corresponding o-allyloxy(arylethynyl)benzene derivatives in good yields without decomposition of the allyloxy group. We have further demonstrated that annulation and enyne metathesis of the o-allyloxy(arylethynyl)benzene derivatives using transition-metal catalysts led to various heterocyclic compounds.
- Watanabe, Kohei,Mino, Takashi,Ishikawa, Eri,Okano, Miyu,Ikematsu, Tatsuya,Yoshida, Yasushi,Sakamoto, Masami,Sato, Kazuki,Yoshida, Kazuhiro
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p. 2359 - 2368
(2017/05/01)
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- Total Synthesis of Dictyodendrins by the Gold-Catalyzed Cascade Cyclization of Conjugated Diynes with Pyrroles
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In total and formal syntheses of dictyodendrins B, C, E, and F, the key step involved the direct construction of the pyrrolo[2,3-c]carbazole core by the gold-catalyzed annulation of a conjugated diyne with a pyrrole to form three bonds and two aromatic rings. The subsequent introduction of substituents at the C1 (Suzuki–Miyaura coupling), C2 (addition to an aldehyde), N3 (alkylation), and C5 positions (Ullman coupling) provided divergent access to dictyodendrins.
- Matsuoka, Junpei,Matsuda, Yuka,Kawada, Yuiki,Oishi, Shinya,Ohno, Hiroaki
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p. 7444 - 7448
(2017/06/13)
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- Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties
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Intramolecular nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole esters is described. Efficient routes towards the synthesis of pyrrolopyrazinone, pyrrolotriazinone and pyrrolooxazinone have been developed. First, N-alkyne-substituted pyrrole ester derivatives were synthesized. Introduction of various substituents into the alkyne functionality was accomplished by a copper-catalyzed cross-coupling reaction. Nucleophilic cyclization of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylates with hydrazine afforded the 6-exo-dig/6-endo-dig cyclization products depending on the electronic nature of the substituents attached to the alkyne. On the other hand, cyclization of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylates with iodine only resulted in the formation of the 6-endo-dig cyclization product regardless of the substitution of the alkyne functionality.
- Yenice, I??l,Basceken, Sinan,Balci, Metin
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p. 825 - 834
(2017/06/20)
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- Controlled Reactivity of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) in the Selective Synthesis of 1-(Bromoethynyl)arenes
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The nucleophilic reactivity of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was completely controlled by the formation of monohydrate (DBU?H2O) in the synthesis of 1-(bromoethynyl)arenes from 1,1-dibromoalkenes. Differential reactivity of DBU in pr
- Krishna Moodapelly, Shiva,Sharma, Gangavaram V. M.,Ramana Doddi, Venkata
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supporting information
p. 1535 - 1540
(2017/05/05)
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- Highly efficient and recyclable catalyst for the direct chlorination, bromination and iodination of terminal alkynes
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Direct halogenation, including chlorination, bromination and iodination of terminal alkynes, are of great importance in organic synthesis. Here an efficient and recyclable nano-Ag/g-C3N4 catalyst system was developed and proved to be remarkably active with 39 examples varied from chlorination, bromination to iodination, of which 14 runs have yielded more than 95% of the product. Recycling of the catalyst was also achieved without obvious activity loss after several runs: 99% yield was observed even after 5 runs in the bromination of phenylacetylene. The catalysts system is of low cost and easy to be prepared, making this procedure versatile, convenient and economic.
- Shi, Wei,Guan, Zhipeng,Cai, Peng,Chen, Hao
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p. 199 - 204
(2017/08/10)
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- Photochemical Dual-Catalytic Synthesis of Alkynyl Sulfides
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A photochemical dual-catalytic cross-coupling to form alkynyl sulfides via C(sp)?S bond formation is described. The cross-coupling of thiols and bromoalkynes is promoted by a soluble organic carbazole-based photocatalyst using continuous flow techniques. Synthesis of alkynyl sulfides bearing a wide range of electronically and sterically diverse aromatic alkynes and thiols can be achieved in good to excellent yields (50–96 %). The simple continuous flow setup also allows for short reaction times (30 min) and high reproducibility on gram scale. In addition, we report the first application of photoredox/nickel dual catalysis towards macrocyclization, as well as the first example of the incorporation of an alkynyl sulfide functional group into a macrocyclic scaffold.
- Santandrea, Jeffrey,Minozzi, Clémentine,Cruché, Corentin,Collins, Shawn K.
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supporting information
p. 12255 - 12259
(2017/09/06)
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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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- Iridium-Catalyzed Highly Regioselective Azide-Ynamide Cycloaddition to Access 5-Amido Fully Substituted 1,2,3-Triazoles under Mild, Air, Aqueous, and Bioorthogonal Conditions
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A highly regioselective method to access 5-amido fully substituted 1,2,3-triazoles by iridium-catalyzed azide-ynamide cycloaddition under mild, air, aqueous, and bioorthogonal conditions is reported. The excellent regioselectivities may derive from the strong coordination between the carbonyl oxygen of ynamide and the -acidic iridium. Since the iridium ion is insensitive to oxygen/water and exhibits low cytotoxicity, it could catalyze this reaction in both organic and biological environments efficiently. Preparation in gram-scale and application in carbohydrates highlight this method.
- Song, Wangze,Zheng, Nan
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supporting information
p. 6200 - 6203
(2017/11/24)
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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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- Cyclobutene vs 1,3-Diene Formation in the Gold-Catalyzed Reaction of Alkynes with Alkenes: The Complete Mechanistic Picture
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The intermolecular gold(I)-catalyzed reaction between arylalkynes and alkenes leads to cyclobutenes by a [2 + 2] cycloaddition, which takes place stepwise, first by formation of cyclopropyl gold(I) carbenes, followed by a ring expansion. However, 1,3-butadienes are also formed in the case of ortho-substituted arylalkynes by a metathesis-type process. The corresponding reaction of alkenes with aryl-1,3-butadiynes, ethynylogous to arylalkynes, leads exclusively to cyclobutenes. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed on the basis of density functional theory calculations, which shows that the two pathways leading to cyclobutenes or dienes are very close in energy. The key intermediates are cyclopropyl gold(I) carbenes, which have been independently generated by retro-Buchner reaction from stereodefined 1a,7b-dihydro-1H-cyclopropa[a]naphthalenes.
- De Orbe, M. Elena,Amenós, Laura,Kirillova, Mariia S.,Wang, Yahui,López-Carrillo, Verónica,Maseras, Feliu,Echavarren, Antonio M.
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supporting information
p. 10302 - 10311
(2017/08/09)
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- Gold-Catalyzed [4+2]- and [3+3]-Annulations of Ynamides with 1-Yn-3-ols to Access Six-Membered Carbocycles and Oxacycles via Three Distinct Cyclizations
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Three distinct strategies for catalytic annulations between ynamides and 1-yn-3-ols are described; the resulting carbo- and heterocycles were produced efficiently in one-pot operations using a gold catalyst. The chemoselectivities of these annulations are controlled by variations of the substituents of the ynamides and the 1-yn-3-ols. This reaction sequence involves initial alkoxylations of ynamides, followed by Claisen rearrangement of propargylic enol ethers, and ends with 6-endo-trig cyclizations of 1-allenyl-5-amide intermediates. Among these cascade annulations, the cyclizations of 5-allenyl-1-amides to yield 5,6-dihydro-2-pyranones and 6-alkylenecyclohex-2-ene-1-carboxamides are unprecedented in the literature. (Figure presented.).
- Giri, Sovan Sundar,Liu, Rai-Shung
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supporting information
p. 3311 - 3318
(2017/09/13)
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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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- TsNBr2mediated oxidative functionalization of alkynes
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A new approach has been developed for oxidative transformation of alkynes by controlled manipulation of TsNBr2mediated process. Alkynes could be readily converted to ketones and α-bromoketones via an oxybromination–debromination sequence. When alkynes are treated successively with TsNBr2, KI and Na2SO3in a mixture of acetone and water at room temperature, corresponding ketones were obtained. On the other hand, treatment of alkynes with TsNBr2and Na2SO3in a mixture of ethyl acetate, acetone and water at room temperature could produce corresponding α-bromoketones. 1-Bromoalkynes could also be synthesized from corresponding alkynes within a very short time using TsNBr2at room temperature. In all cases, excellent yields of corresponding products are obtained.
- Rajbongshi, Kamal Krishna,Hazarika, Debojit,Phukan, Prodeep
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p. 4151 - 4158
(2016/07/06)
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- Copper(I)-Catalyzed Three-Component Click/Alkynylation: One-Pot Synthesis of 5-Alkynyl-1,2,3-triazoles
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A copper(I)-catalyzed tandem CuAAC/alkynylation reaction of various alkynes, organic azides, and bromoalkynes to provide rapid access to 5-alkynyl-1,2,3-triazoles has been developed. The reaction proceeded via a copper-catalyzed alkyne azide cycloaddition
- Wang, Weiguo,Wei, Fang,Ma, Yudao,Tung, Chen-Ho,Xu, Zhenghu
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supporting information
p. 4158 - 4161
(2016/10/11)
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- Gold-catalyzed [3+2]-annulations of α-aryl diazonitriles with ynamides and allenamides to yield 1-amino-1H-indenes
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Gold-catalyzed [3+2]-annulations of α-aryl diazonitriles with ynamides and allenamides yield 1-amino-1H-indenes in two distinct pathways; the success of these annulations relies on the high electrophilicity of α-cyano arylgold carbenes to activate an ionic pathway.
- Singh, Rahulkumar Rajmani,Pawar, Samir Kundlik,Huang, Min-Jie,Liu, Rai-Shung
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supporting information
p. 11434 - 11437
(2016/09/23)
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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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- Regioselective Synthesis of Polyheterohalogenated Naphthalenes via the Benzannulation of Haloalkynes
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Independent control of halide substitution at six of the seven naphthalene positions of 2-arylnaphthalenes is achieved through the regioselective benzannulation of chloro-, bromo-, and iodoalkynes. The modularity of this approach is demonstrated through the preparation of 44 polyheterohalogenated naphthalene products, most of which are difficult to access through known naphthalene syntheses. The outstanding regioselectivity of the reaction is both predictable and proven unambiguously by single-crystal X-ray diffraction for many examples. This synthetic method enables the rapid preparation of complex aromatic systems poised for further derivatization using established cross-coupling methods. The power and versatility of this approach makes substituted naphthalenes highly attractive building blocks for new organic materials and diversity-oriented synthesis.
- Lehnherr, Dan,Alzola, Joaquin M.,Lobkovsky, Emil B.,Dichtel, William R.
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supporting information
p. 18122 - 18127
(2015/12/24)
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