- Intermolecular Desymmetrizing Gold-Catalyzed Yne–Yne Reaction of Push–Pull Diarylalkynes
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Push–pull diaryl alkynes are dimerized in the presence of a cationic gold catalyst. The polarized structure of the applied starting materials enables the generation of a highly reactive vinyl cation intermediate in an intermolecular reaction. Trapping of the vinyl cation by a nucleophilic attack of the electron-poor aryl unit then leads to the selective formation of highly substituted naphthalenes in a single step and in complete atom economy.
- Weingand, Vanessa,Wurm, Thomas,Vethacke, Vanessa,Dietl, Martin C.,Ehjeij, Daniel,Rudolph, Matthias,Rominger, Frank,Xie, Jin,Hashmi, A. Stephen K.
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Read Online
- Catalytic Access to Functionalized Allylic gem-Difluorides via Fluorinative Meyer–Schuster-Like Rearrangement
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An unprecedented approach for efficient synthesis of functionalized allylic gem-difluorides via catalytic fluorinative Meyer–Schuster-like rearrangement is disclosed. This transformation proceeded with readily accessible propargylic fluorides, and low-cost B–F reagents and electrophilic reagents by sulfide catalysis. A series of iodinated, brominated, and trifluoromethylthiolated allylic gem-difluorides that were difficult to access by other methods were facilely produced with a wide range of functional groups. Importantly, the obtained iodinated products could be incorporated into different drugs and natural products, and could be expediently converted into many other valuable gem-difluoroalkyl molecules as well. Mechanistic studies revealed that this reaction went through a regioselective fluorination of alkynes followed by a formal 1,3-fluorine migration under the assistance of the B–F reagents to give the desired products.
- An, Rui,Li, Huimin,Liao, Lihao,Wu, Jin-Ji,Xu, Yang,Zhao, Xiaodan
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supporting information
p. 11010 - 11019
(2020/05/18)
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- Palladium-Catalyzed Intermolecular Aryliodination of Internal Alkynes
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A completely atom economical palladium-catalyzed addition reaction has been developed to stereoselectively access functionalized tetrasubstituted alkenyl iodides. The palladium catalyst, which bears an electron-poor bidentate ligand rarely employed in catalysis, is essential to promote the high yielding and chemoselective intermolecular reaction between equimolar amounts of an alkyne and an aryl iodide. This new carbohalogenation reaction is an attractive alternative to traditional synthetic methods, which rely on multistep synthetic sequences and protecting-group manipulations.
- Lee, Yong Ho,Morandi, Bill
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supporting information
p. 6444 - 6448
(2019/03/07)
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- Development of highly chemoselective bulky zincate complex, tBu 4ZnLi2: Design, structure, and practical applications in small-/macromolecular synthesis
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We present full details of the unique reactivities of the newly developed dianion-type bulky zincate, dilithium tetra-ferf-butylzincate (tBu 4ZnLi2). With this reagent, halogen-zinc exchange reaction of variously functionalized haloaromatics and anionic polymerization of N-isopropylacrylamide (NIPAm)/styrene with excellent chemoselectivity were realized. Halogen-zinc exchange reaction followed by electrophilic trapping with propargyl bromide provided a convenient route to functionalized phenylallenes, particularly those with electrophilic functional groups (such as cyano, amide and halogens). Spectral and computational studies of the structure in the gas and liquid phases indicated extraordinary stabilization of this dianion-type zincate by its bulky ligands.
- Furayama, Taniyuki,Yonehara, Mitsuhiro,Arimoto, Sho,Kobayashi, Minoru,Matsumoto, Yotaro,Uchiyama, Masanobu
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supporting information; experimental part
p. 10348 - 10356
(2009/10/10)
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- Toward a protecting-group-free halogen-metal exchange reaction: Practical, chemoselective metalation of functionalized aromatic halides using dianion-type zincate,tBu4ZnLi2
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A versatile preparation method for aromatic zincate compounds through a halogen-zinc exchange reaction using dilithium tetra-tert-butylzincate (tBu4ZnLi2) has been developed. This reagent permits efficient preparation of highly functionalized aromatic zincates, particularly, those with electrophilic functional groups, such as ester, amide, alcohol, and phenol. Halogen-zinc exchange reactions followed by electrophilic trapping (with allyl bromide or benzaldehyde) proved to be a powerful tool for C-C bond formation on functionalized aromatic rings. The functionalized aromatic zincate intermediate was also found to undergo copper- and palladium-catalyzed C-C bond-forming reactions with good yields and high chemoselectivity. Copyright
- Uchiyama, Masanobu,Furuyama, Taniyuki,Kobayashi, Minoru,Matsumoto, Yotaro,Tanaka, Kentaro
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p. 8404 - 8405
(2007/10/03)
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- Iron-catalyzed aryl-aryl cross-couplings with magnesium-derived copper reagents
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(Chemical Equation Presented) Well-matched couples: Functionalized aryl and heteroaryl copper species obtained from the corresponding magnesium derivatives undergo Fe-catalyzed cross-coupling reactions with aryl iodides that bear keto, ester, triflate, or nitrile groups (see scheme).
- Sapountzis, Ioannis,Lin, Wenwei,Kofink, Christiane C.,Despotopoulou, Christina,Knochel, Paul
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p. 1654 - 1657
(2007/10/03)
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- A high throughput synthesis of aryl triflate and aryl nonaflate promoted by a polymer supported base (PTBD)
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A rapid synthesis of aryl triflate and aryl nonaflate was developed using 4-nitrophenyl triflate and 4-nitrophenyl nonaflate as perfluoroalkanesulfonyl transfer reagents in combination with a polymer supported base (PTBD). Simple filtration of the reactio
- Boisnard, Sabine,Chastanet, Jaqueline,Zhu, Jieping
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p. 7469 - 7472
(2007/10/03)
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- Facile syntheses of aryldifluorophosphonate building blocks
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The copper-catalysed zinc phosphonate chemistry described by Yokomatsu and Shibuya can be used directly in the synthesis of phosphotyrosine analogue F2Pmp, and in entering the classical organometallic coupling repertoire via Stille and Suzuki-M
- Cockerill, G. Stuart,Easterfield, Howard J.,Percy, Jonathan M.
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p. 2601 - 2604
(2007/10/03)
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- 4-Nitrophenyltriflate as a New Triflating Agent
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Aryl triflates were prepared under mild conditions using 4-nitrophenyl triflate (1) as a stable, crystalline triflating agent.
- Zhu, Jieping,Bigot, Antony,Elise, Marie,Dau, Tran Huu
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p. 1181 - 1182
(2007/10/03)
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- First synthesis of ortho-trifluoromethylated aryl triflates
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An efficient method for the preparation of trifluoromethylated aryl triflates (trifluoromethanesulfonates) has been developed. Treatment of 2-iodophenol with trifluoromethanesulfonic anhydride in the presence of triethylamine gives triflate 3. Then, reaction of compound 3 with FSO2CF2CO2Me and CuI in DMF-HMPA affords trifluoromethylated aryl triflate 2. This reaction sequence is also successful for meta- and para-trifluoromethylated aryl triflates. Based on this methodology, the trifluoromethylated aryl triflate 11, a key intermediate for the preparation of the conformationally restricted retinoid 8 containing a trifluoromethyl group, has been synthesized. The cross-coupling of aryl triflate 11 with vinylstannane 17 under palladium catalysis provides compound 18, the methyl ester of retinoid 8, in moderate yield.
- Qing, Feng-Ling,Fan, Junfa,Sun, Hong-Bin,Yue, Xiang-Jun
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p. 3053 - 3057
(2007/10/03)
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