- Aerobic Cu-catalyzed oxidative 1?:?2 coupling of benzynes with terminal alkynes
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Cu-Catalyzed oxidative 1?:?2 couplings of arynes with nucleophilic terminal alkynes under aerobic conditions are described herein. A mechanistic investigation revealed a plausible involvement of an aryl-Cu(iii)-generating pathway. By this method, ubiquitous arenediynes can be efficiently assembled in a single step under mild conditions. This journal is
- Lu, Tianhao,Shen, Yong,Wang, Min,Zhang, Zibing,Li, Shijun,Xie, Chunsong
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- Orbital Crossings Activated through Electron Injection: Opening Communication between Orthogonal Orbitals in Anionic C1-C5 Cyclizations of Enediynes
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Generally, the long-range electronic communication between spatially orthogonal orbitals is inefficient and limited to field and inductive effects. In this work, we provide experimental evidence that such communication can be achieved via intramolecular electron transfer between two degenerate and mutually orthogonal frontier molecular orbitals (MOs) at the transition state. Interaction between orthogonal orbitals is amplified when the energy gap between these orbitals approaches zero, or at an “orbital crossing”. The crossing between two empty or two fully occupied MOs, which do not lead to stabilization, can be “activated” when one of the empty MOs is populated (i.e., electron injection) or one of the filled MOs is depopulated (i.e., hole injection). In reductive cycloaromatization reactions, such crossings define transition states with energies defined by both the in-plane and out-of-plane π-systems. Herein, we provide experimental evidence for the utility of this concept using orbital crossings in reductive C1-C5 cycloaromatization reactions of enediynes. Communication with remote substituents via orbital crossings greatly enhances regioselectivity of the ring closure step in comparison to the analogous radical cyclizations. We also present photophysical data pertaining to the efficiency of electron injection into the benzannelated enediynes.
- Peterson, Paul W.,Shevchenko, Nikolay,Breiner, Boris,Manoharan, Mariappan,Lufti, Forat,Delaune, Jess,Kingsley, Margaret,Kovnir, Kirill,Alabugin, Igor V.
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supporting information
p. 15617 - 15628
(2016/12/16)
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- Copper-catalyzed decarboxylative cross-coupling of alkynyl carboxylic acids with aryl halides
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The copper-catalyzed decarboxylative reactions of alkynyl carboxylic acids with aryl halides were performed under relatively mild reaction conditions. Benzofurans could be further prepared smoothly by a one-pot domino protocol on the basis of decarboxylative cross-coupling of 2-iodophenol.
- Zhao, Dongbing,Gao, Chao,Su, Xiaoyu,He, Yunqing,You, Jingsong,Xue, Ying
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supporting information; experimental part
p. 9049 - 9051
(2011/02/17)
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- Tellurium-Mediated Halogen Transer from Polyhaloalkanes to Diyne Acceptors
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Elemental tellurium catalyzes transfer of halogen from (CHCl2)2, from C2HCl5 and from (CHBr2)2, to the phenylated diynes 1-3, 17, 20, and 24, in which the alkyne moieties are in close proximity.The process is associated with cyclorearrangement reactions by which halogenated polycycles are formed.In boiling C2HCl5, derivatives of 1,2-bis(phenylethynyl)benzenes afford 5-halogenated indenoindenes, 1,8-bis(phenylethynyl)naphthalene gives a chlorinated benzofluoranthene derivative, and 2,2'-bis(phenylethynyl) forms 9-chloro-14-phenylbenzanthracene.Diynes 25 and 26 in which the ethynyl functions are further removed from each other fail to yield halogenated products.Diyne 25 undergoes oxidative cyclization by which 1,3-diphenyldibenzocycloheptafuran (29) is formed.Compound 26 is transformed to hydrocarbon 32, which involves a phenyl ring walk and elimination of H2Te.
- Blum, Jochanan,Baidossi, Wael,Badriech, Yacoub,Hoffman, Roy E.,Schumann, Herbert
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p. 4738 - 4742
(2007/10/02)
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