- Metal-Free Aryl Cross-Coupling Directed by Traceless Linkers
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The metal-free, highly selective synthesis of biaryls poses a major challenge in organic synthesis. The scope and mechanism of a promising new approach to (hetero)biaryls by the photochemical fusion of aryl substituents tethered to a traceless sulfonamide linker (photosplicing) are reported. Interrogating photosplicing with varying reaction conditions and comparison of diverse synthetic probes (40 examples, including a suite of heterocycles) showed that the reaction has a surprisingly broad scope and involves neither metals nor radicals. Quantum chemical calculations revealed that the C?C bond is formed by an intramolecular photochemical process that involves an excited singlet state and traversal of a five-membered transition state, and thus consistent ipso–ipso coupling results. These results demonstrate that photosplicing is a unique aryl cross-coupling method in the excited state that can be applied to synthesize a broad range of biaryls.
- Haensch, Veit G.,Neuwirth, Toni,Steinmetzer, Johannes,Kloss, Florian,Beckert, Rainer,Gr?fe, Stefanie,Kupfer, Stephan,Hertweck, Christian
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supporting information
p. 16068 - 16073
(2019/11/28)
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- Synthesis of 2-substituted benzo[: B] thiophenes via gold(i)-NHC-catalyzed cyclization of 2-alkynyl thioanisoles
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Benzo[b]thiophene heterocycles are important components of many important small molecule pharmaceuticals and drug candidates as well as organic semiconducting materials. Many methods have been developed for the construction of a benzo[b]thiophene core via cyclization reaction of alkynes. Although few catalytic reactions were disclosed, most methods rely on stoichiometric activation of alkynes. Here we report an efficient method for the synthesis of 2-substituted benzo[b]thiophenes from 2-alkynyl thioanisoles catalyzed by a gold(i)-IPr hydroxide that is applicable to a wide range of substrates with diverse electronic and steric properties. Additionally, we demonstrate experimentally that the acid additive and its conjugate base are essential to catalyst turnover.
- Dillon, Christopher C.,Keophimphone, Bagieng,Sanchez, Melissa,Kaur, Parveen,Muchalski, Hubert
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p. 9279 - 9284
(2019/01/03)
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- Ag(I)-C-H Activation Enables Near-Room-Temperature Direct α-Arylation of Benzo[ b]thiophenes
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The first example of near-room-temperature α-arylation of benzo[b]thiophenes is reported. The discovery rests on the observation of a switch in α-/β-regioselectivity at different loadings of Pd2(dba)3·CHCl3 in the coupling between benzo[b]thiophene and 4-iodotoluene. We show that this unprecedented regioselectivity switch is driven by a Ag(I)-mediated C-H activation at the α-C-H position, which becomes the dominant mode of reactivity at low concentrations of Pd. Competition experiments, kinetic studies, KIE, and D/H scrambling experiments have been carried out supporting this mechanism.
- Colletto, Chiara,Panigrahi, Adyasha,Fernández-Casado, Jaime,Larrosa, Igor
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supporting information
p. 9638 - 9643
(2018/07/21)
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- Room-temperature arylation of arenes and heteroarenes with diaryliodonium salts by photoredox catalysis
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Aryl radicals produced by irradiation of diaryliodonium salts with visible light under the catalysis of [Ru(bpy)3]2+ undergo coupling with a wide range of arenes and heteroarenes, affording various biaryls through direct C-H arylation at room temperature. Georg Thieme Verlag Stuttgart · New York.
- Liu, Yu-Xia,Xue, Dong,Wang, Jia-Di,Zhao, Cong-Jun,Zou, Qing-Zhu,Wang, Chao,Xiao, Jianliang
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supporting information
p. 507 - 513
(2013/04/10)
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- SPIROCHROMANON DERIVATIVES
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The invention relates to a compound of a general formula (I): wherein Ar1 represents a group formed from an aromatic ring selected from a group consisting of benzene, pyrazole, isoxazole, pyridine, indole, 1H-indazole, 1H-furo[2,3-c]pyrazole, 1H-thieno[2,3-c]pyrazole, benzimidazole, 1,2-benzisoxazole, imidazo[1,2-a]pyridine, imidazo[1,5-a]pyridine and 1H-pyrazolo[3,4-b]pyridine, having Ar2, and optionally having one or two or more substituents selected from R3; R1 and R2 each independently represent a hydrogen atom, a halogen atom, a cyano group, a C2-C6 alkenyl group, a C1-C6 alkoxy group, a C2-C7 alkanoyl group, a C2-C7 alkoxycarbonyl group, an aralkyloxycarbonyl group, a carbamoyl-C1-C6 alkoxy group, a carboxy-C2-C6 alkenyl group, or a group of -Q1-N(Ra)-Q2-Rb; or a C1-C6 alkyl group optionally having a substituent; or an aryl or heterocyclic group optionally having a substituent; or a C1-C6 alkyl group or a C2-C6 alkenyl group having the aryl or heterocyclic group; T and U each independently represent a nitrogen atom or a methine group; and V represents an oxygen atom or a sulfur atom. The compound of the invention is useful as therapeutical agents for various ACC-related diseases.
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Page/Page column 121
(2008/12/07)
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- PALLADIUM-CATALYZED ARYLATION OF FURAN, THIOPHENE, BENZOFURAN AND BENZOTHIOPHENE
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Treatment of ?-electron sufficient aromatic heterocycles such as furan, thiophene, benzofuran and benzothiophene with aryl bromides in the presence of tetrakis(triphenyphosphine)palladium gave the corresponding 2-aryl aromatic heterocycles.
- Ohta, Akihiro,Akita, Yasuo,Ohkuwa, Teruya,Chiba, Mari,Fukunaga, Ryuichi,et al.
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p. 1951 - 1958
(2007/10/02)
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