- Enabling the Use of Alkyl Thianthrenium Salts in Cross-Coupling Reactions by Copper Catalysis
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Alkyl groups are one of the most widely used groups in organic synthesis. Here, a a series of thianthrenium salts have been synthesized that act as reliable alkylation reagents and readily engage in copper-catalyzed Sonogashira reactions to build C(sp3)?C(sp) bonds under mild photochemical conditions. Diverse alkyl thianthrenium salts, including methyl and disubstituted thianthrenium salts, are employed with great functional breadth, since sensitive Cl, Br, and I atoms, which are poorly tolerated in conventional approaches, are compatible. The generality of the developed alkyl reagents has also been demonstrated in copper-catalyzed Kumada reactions.
- Chen, Cheng,Lu, Hongjian,Shi, Zhuangzhi,Wang, Minyan,Zhao, Binlin
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p. 21756 - 21760
(2021/08/30)
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- Rh(iii)-Catalyzed olefination to build diverse oxazole derivatives from functional alkynes
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A novel Rh(iii)-catalyzed olefination reaction of oxazoles to generate diverse oxazole skeleton derivatives has been realized by directly using oxazole as the directing group. The reaction could tolerate many functional groups, affording complex oxazole derivatives with long chain alkenyls in moderate to good yields, which might find applications in the construction of diverse compounds.
- He, Yuan,Zheng, Ting,Huang, Yin-Hui,Dong, Lin
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supporting information
p. 4937 - 4942
(2021/06/16)
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- Switch in Selectivity for Formal Hydroalkylation of 1,3-Dienes and Enynes with Simple Hydrazones
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Controlling reaction selectivity is a permanent pursuit for chemists. Regioselective catalysis, which exploits and/or overcomes innate steric and electronic bias to deliver diverse regio-enriched products from the same starting materials, represents a powerful tool for divergent synthesis. Recently, the 1,2-Markovnikov hydroalkylation of 1,3-dienes with simple hydrazones was reported to generate branched allylic compounds when a nickel catalyst was used. As part of the effort, shown here is that a complete switch of Markovnikov to anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes.
- Li, Chao-Jun,Lv, Leiyang,Qiu, Zihang,Yu, Lin
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supporting information
p. 6466 - 6472
(2020/03/13)
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- Iron-Catalyzed Cross-Coupling of Alkynyl and Styrenyl Chlorides with Alkyl Grignard Reagents in Batch and Flow
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Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables the formation of Csp?Csp3 and Csp2?Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity.
- Deng, Yuchao,Wei, Xiao-Jing,Wang, Xiao,Sun, Yuhan,No?l, Timothy
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p. 14532 - 14535
(2019/11/21)
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- Sonogashira Cross-Coupling of Aryltrimethylammonium Salts
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A protocol for C(sp)-C(sp2) bond formation via the Sonogashira coupling reaction involving C-N bond cleavage with aryltrimethylammonium triflate as an electrophilic coupling partner is described in this work. The reactions proceeded well under mild conditions with a stoichiometric ratio of alkyl, aryl, or heteroaryl acetylenes and provided yields of up to 93%. Numerous useful functional groups were tolerated under the reaction conditions. Direct amine alkynylation can be achieved through a one-pot process without the isolation of ammonium salt. The protocol can be performed on a gram scale. Density functional theory calculations were performed to investigate the reaction mechanism that involved oxidative addition, alkyne coordination, deprotonation, and reductive elimination, which yielded the cross-coupling product.
- Chen, Qianwei,Gao, Fengchen,Tang, Huiling,Yao, Miao,Zhao, Qian,Shi, Yanhui,Dang, Yanfeng,Cao, Changsheng
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p. 3730 - 3736
(2019/04/13)
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- Decarboxylative Negishi Coupling of Redox-Active Aliphatic Esters by Cobalt Catalysis
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A cobalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl–aryl, alkyl–alkenyl, and alkyl–alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that a radical mechanism is involved.
- Liu, Xu-Ge,Zhou, Chu-Jun,Lin,Han, Xiang-Lei,Zhang, Shang-Shi,Li, Qingjiang,Wang, Honggen
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p. 13096 - 13100
(2018/09/21)
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- Transmetalation of Alkylzirconocenes in Copper-Catalyzed Alkyl–Alkynyl Cross-Coupling Reactions
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A simple copper-catalyzed alkyl–alkynyl cross-coupling strategy has been developed using the reaction between alkynyl bromides and alkylzirconocenes. The alkylzirconocenes were generated in situ via regioselective addition of Schwartz's reagent (ZrCp2HCl) on to alkenes. The reaction has a broad scope, a range of functionalized bromoalkynes and alkylzirconium reagents were successfully coupled, resulting in moderate to good yields of the desired internal alkynes. (Figure presented.).
- Indukuri, Kiran,Riant, Olivier
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p. 2425 - 2433
(2017/07/22)
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- Nickel-catalyzed cross-coupling of primary alkyl halides with phenylethynyl- and trimethylsilyethynyllithium reagents
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A highly efficient alkyl-alkynyl coupling system is described which is promoted by a well-defined and moisture-stable pincer complex [NiCl{C 6H3-2,6-(OPPh2)2}] (1). Non-activated alkyl halides could be efficient
- Xu, Guoqiang,Li, Xiaoyan,Sun, Hongjian
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supporting information; experimental part
p. 3011 - 3014
(2011/08/22)
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- Selective synthesis of allenes and alkynes through ligand-controlled, palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates
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Ligand-controlled regioselective palladium-catalyzed decarboxylative hydrogenolysis of propargylic formates is described. A wide range of allenes and alkynes were obtained by using either 1,2-diphenylphosphinoethane (DPPE) or 1,6-bisdiphenylphosphinohexane (DPPH) as a catalyst ligand.
- Ohmiya, Hirohisa,Yang, Mingyu,Yamauchi, Yoshihiro,Ohtsuka, Yuhki,Sawamura, Masaya
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supporting information; experimental part
p. 1796 - 1799
(2010/09/07)
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- Novel Synthesis of Disubstituted Alkyne Using Molybdenum Catalyzed Cross-Alkyne Metathesis
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A novel disubstituted alkyne synthesis was developed using molybdenum catalyzed cross-alkyne metathesis by Mortreux's catalyst .The reaction was carried out using Mo(CO)6 (5 molpercent for total amounts of alkynes) and p-ClC6H4OH (1 equiv.) in the presence of an excess amount of another alkyne (3-11 equiv.) in rexluxing toluene.
- Kaneta, Naotake,Hikichi, Ken,Asaka, Shin-ichi,Uemura, Motokazu,Mori, Miwako
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p. 1055 - 1056
(2007/10/03)
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