- Hydromagnesiation of 1,3-Enynes by Magnesium Hydride for Synthesis of Tri- and Tetra-substituted Allenes
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A protocol for regio-controlled hydromagnesiation of 1,3-enynes was developed using magnesium hydride that is generated in situ by solvothermal treatment of sodium hydride (NaH) and magnesium iodide (MgI2) in THF. The resulting allenylmagnesium species could be converted into tri- and tetra-substituted allenes by subsequent treatment with various carbon- and silicon-based electrophiles with the aid of CuCN as a catalyst.
- Chiba, Shunsuke,Li, Yihang,Pang, Jia Hao,Takita, Ryo,Wang, Bin,Watanabe, Kohei
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supporting information
p. 217 - 221
(2020/11/30)
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- Synthesis of α-Alkynylnitrones via Hydromagnesiation of 1,3-Enynes with Magnesium Hydride
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A protocol for the synthesis of α-Alkynylnitrones from 1,3-enynes has been developed. The process is triggered by hydromagnesiation of 1,3-enynes with magnesium hydride (MgH2), which is prepared in situ through solvothermal treatment of magnesium iodide (
- Li, Yihang,Ng, Jia Sheng,Wang, Bin,Chiba, Shunsuke
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supporting information
p. 5060 - 5064
(2021/06/30)
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- Stereodivergent Synthesis of Tertiary Fluoride-Tethered Allenes via Copper and Palladium Dual Catalysis
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Herein we describe a protocol for the unprecedented stereodivergent synthesis of tertiary fluoride-tethered allenes bearing a stereogenic center and stereogenic axis via Cu/Pd synergistic catalysis. A broad scope of conjugated enynes are coupled with various α-fluoroesters in high yields with high diastereoselectivities and generally >99% ee. In addition, the four stereoisomers of the allene products ensure precise access to the corresponding four stereoisomers of the fluorinated hydrofurans via a novel stereodivergent axial-to-central chirality transfer process.
- Yang, Shao-Qian,Wang, Yi-Fan,Zhao, Wei-Cheng,Lin, Guo-Qiang,He, Zhi-Tao
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supporting information
p. 7285 - 7291
(2021/05/26)
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- Regioselective Access to 3-Ethylideneflavanones via Rhodium(I)-Catalyzed 1,3-Enyne Hydroacylation/Annulation Cascades
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The highly efficient synthesis of 3-ethylideneflavanones through sequential rhodium(I)-catalyzed hydroacylation of terminal aryl-substituted 1,3-enynes with chelating aldehydes and annulation is described. This straightforward protocol highlights an unprecedented C3-regioselective hydroacylation of 1,3-enynes, excellent functional group compatibility, and complete atom economy. (Figure presented.).
- Chang, Zhi-Xin,Li, Fu-Rong,Xia, Chengcai,Li, Fei,Li, Hong-Shuang
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supporting information
p. 1722 - 1726
(2021/02/20)
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- Fe-Catalyzed Selective Cyclopropanation of Enynes under Photochemical or Thermal Conditions
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The nucleophilic Fe-complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the cyclopropanation of enynes to substituted propargyl cyclopropanes using diazoesters as carbene surrogates. The catalyst can be activated either thermally in the presence of catalytic amounts of 4-nitroanisole or under photochemical conditions. Cyclopropanation occurs selectively at the enyne moiety; alternative olefinic moieties remain intact.
- Picher, Marie-Idrissa,Plietker, Bernd
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p. 340 - 344
(2020/01/11)
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- Enantioselective Synthesis of Multisubstituted Allenes by Cooperative Cu/Pd-Catalyzed 1,4-Arylboration of 1,3-Enynes
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A cooperative Cu/Pd-catalyzed enantioselective synthesis of multisubstituted allenes is established. By employing chiral sulfoxide phosphine (SOP)/Cu and PdCl2(dppf) complexes as catalysts, the 1,4-arylboration of 1,3-enynes provides an efficient approach to trisubstituted chiral allenes with up to 92 % yield and 97:3 er. Furthermore, by using 2-substituted 1,3-enynes as substrates, the tetrasubstituted chiral allenes were successfully generated using this strategy. Finally, theoretical calculations indicate that the transmetallation of the allenylcopper species is the rate-limiting step of this transformation.
- Liao, Yang,Yin, Xuemei,Wang, Xihong,Yu, Wangzhi,Fang, Dongmei,Hu, Lianrui,Wang, Min,Liao, Jian
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supporting information
p. 1176 - 1180
(2019/12/11)
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- Direct access to pentenedinitriles: Via Ni-catalyzed dihydrocyanation of 1,3-enynes
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A highly regio-and stereoselective dihydrocyanation of 1,3-enynes was implemented by nickel/diphosphine catalysts. This reaction represents the first example of Ni-catalyzed dihydrocyanation of 1,3-enynes using TMSCN and MeOH as HCN surrogates. In this tr
- Fang, Xianjie,Gao, Jihui,Sun, Feilong
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supporting information
p. 6858 - 6861
(2020/07/04)
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- Cobalt-Catalyzed gem-Cross-Dimerization of Terminal Alkynes
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Transition-metal-catalyzed dimerization of two different terminal alkynes provides an atom-economic synthesis of valuable conjugated 1,3-enynes. Despite many catalyst systems developed, the state-of-the-art solutions are still limited to special alkynes. A practical catalyst, which could be used to cross-dimerize general aryl alkynes and aliphatic alkynes, is still highly desired. Herein we present the earth-abundant Co(II)-catalyzed highly gem-selective cross-dimerization of aryl alkynes and aliphatic alkynes or gas acetylene under mild reaction conditions. Conjugated 1,3-enynes with various useful functional groups can be prepared in high yields. The application of Co(OAc)2 and t-butyl group substituted triphos ligand is essential to distinguish the alkynes at different steps and realize the gem-selectivity.
- Chen, Jia-Feng,Li, Changkun
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p. 3881 - 3889
(2020/03/26)
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- A Drastic Effect of TEMPO in Zinc-Catalyzed Stannylation of Terminal Alkynes with Hydrostannanes via Dehydrogenation and Oxidative Dehydrogenation
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With a system consisting of a catalytic zinc Lewis acid, pyridine, and TEMPO in a nitrile medium, terminal alkynes coupled with HSnBu3, providing alkynylstannanes with structural diversity. The resulting alkynylstannane, without being isolated, could be directly used for Pd- and Cu-catalyzed transformations to deliver internal alkynes and more intricate tin-atom-containing molecules. Mechanistic studies indicated that TEMPOSnBu3 formed in situ from TEMPO and HSnBu3 works to stannylate the terminal alkyne in collaboration with the zinc catalyst, and that both of dehydrogenation and oxidative dehydrogenation processes are uniquely involved in a single reaction. (Figure presented.).
- Kai, Yuichi,Oku, Shinya,Sakurai, Kyoko,Tani, Tomohiro,Tsuchimoto, Teruhisa
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supporting information
(2019/08/21)
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- Preparation of Chiral Allenes through Pd-Catalyzed Intermolecular Hydroamination of Conjugated Enynes: Enantioselective Synthesis Enabled by Catalyst Design
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In this study, we establish that conjugated enynes undergo selective 1,4-hydroamination under Pd catalysis to deliver chiral allenes with pendant allylic amines. Several primary and secondary aliphatic and aryl-substituted amines couple with a wide range of mono- and disubstituted enynes in a nonenantioselective reaction where DPEphos serves as the ligand for Pd. Benzophenone imine acts as an ammonia surrogate to afford primary amines in a two-step/one-pot process. Examination of chiral catalysts revealed a high degree of reversibility in the C-N bond formation that negatively impacted enantioselectivity. Consequently, an electron-poor ferrocenyl-PHOX ligand was developed to enable efficient and enantioselective enyne hydroamination.
- Adamson, Nathan J.,Jeddi, Haleh,Malcolmson, Steven J.
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supporting information
p. 8574 - 8583
(2019/06/04)
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- Triple-Bond Insertion Triggers Highly Regioselective 1,4-Aminomethylamination of 1,3-Enynes with Aminals Enabled by Pd-Catalyzed C-N Bond Activation
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A highly chemo- and regioselective 1,4-aminomethylamination of simple enynes with aminals to allenic 1,5-diamines by taking advantage of C-N bond activation has been reported. The reaction proceeds under mild reaction conditions and can be performed under
- Zhang, Yanchen,Yu, Bangkui,Gao, Binjian,Zhang, Tianze,Huang, Hanmin
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supporting information
(2019/01/21)
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- Triple-Bond Insertion Triggers Highly Regioselective 1,4-Aminomethylamination of 1,3-Enynes with Aminals Enabled by Pd-Catalyzed C-N Bond Activation
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A highly chemo- and regioselective 1,4-aminomethylamination of simple enynes with aminals to allenic 1,5-diamines by taking advantage of C-N bond activation has been reported. The reaction proceeds under mild reaction conditions and can be performed under
- Zhang, Yanchen,Yu, Bangkui,Gao, Binjian,Zhang, Tianze,Huang, Hanmin
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supporting information
p. 535 - 539
(2019/01/24)
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- Redox-Neutral Annulation of Alkynylcyclopropanes with N-Aryloxyamides via Rhodium(III)-Catalyzed Sequential C-H/C-C Activation
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Alkynylcyclopropanes have been used for the first time as coupling partners in transition-metal-catalyzed C-H functionalization. Specifically, a Cp?RhIII-catalyzed regioselective annulation of alkynylcyclopropanes with N-aryloxyamides via redox
- Li, Yang,Shi, Dandan,He, Xin,Wang, Yongzhuang,Tang, Yuhai,Zhang, Junjie,Xu, Silong
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p. 1588 - 1595
(2019/01/21)
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- Regioselective solvent-dependent benzannulation of conjugated enynes
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The transformation of enynes under cobalt-catalysis leads to symmetrical benzannulation products in dichloromethane. In tetrahydrofuran the cobalt-catalysed reactions afforded the unprecedented unsymmetrical benzannulation products in moderate to good yields and good regioselectivities. In addition, cyclotrimerisation of the alkyne subunit can be realised when electron-deficient enynes are applied in the cobalt-catalysed transformations to generate 1,2,4-trivinylbenzene derivatives using tetrahydrofuran as solvent.
- Puenner, Florian,Hilt, Gerhard
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p. 3617 - 3619
(2012/05/20)
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- Iron-catalyzed preparation of trifluoromethyl substituted vinyl- and alkynylcyclopropanes
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A convenient iron-catalyzed procedure to prepare trifluoromethylated vinyl- and alkynylcyclopropanes in a chemo- and diastereoselective manner is presented. The active diazo compound (trifluoromethyl diazomethane) is generated in situ and used in the conc
- Morandi, Bill,Cheang, Jeremy,Carreira, Erick M.
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supporting information; experimental part
p. 3080 - 3081
(2011/08/04)
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- Convenient access to functionalized vinylcyclopentenols from alkynyloxiranes
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β,γ-Alkynyl aldehydes, generated in situ by treatment of alkynyloxiranes with a catalytic amount of Sc(OTf)3 or BF 3· OEt2, are effectively trapped by a variety of allyl nucleophiles to afford homopropargylic homoallylic a
- Wang, Letian,Maddess, Matthew L.,Lautens, Mark
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p. 1822 - 1825
(2007/10/03)
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- Vinyl Cations. 41. Influence of 4-Aryl and 4-Alkyl Substituents on the ?-Route Solvolyses of Homopropargyl Esters
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The four 4-substituted-homopropargyl tosylates and triflates 6b-e (R=phenyl, p-tolyl, anisyl, and cyclopropyl) have been synthesized and solvolyzed under various conditions, as have 2-cyclopropyl-1-cyclobutenyl triflate (11-OTf) and nonaflate (11-ONf).In addition, the solvolyses of pent-3-yn-1-yl tosylate (6a-OTs, R=methyl) and triflate (prepared previously) are reported.The ratios of C-3 ring to C-4 ring 3 ring/C4ring)> products are recorded for the reactions in various solvents.As expected, ring closure (kΔ) increases and solvent displacement (kS, SN2) decreases with decreasing nucleophilicity of solvent.Temperature effects are noted for the sovolyses of tosylates 6a-e in 100percent TFE buffered with Na2CO3 in which kΔ increases with increasing temperature.The result is explained by decomposition of the intimate ion pair with temperature, whereupon elimination to the enyne becomes smaller and ring closure (kΔ) increases at the expense of elimination.The possibility of intervention of nonclassical vinyl cations is discussed, as are other mechanistic implications.
- Collins, Clair J.,Hanack, Michael,Stutz, Herbert,Auchter, Gerhard,Schoberth, Winfried
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p. 5260 - 5268
(2007/10/02)
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