Palladium-Catalyzed Coupling Reactions of Bromothiophenes at the C−H Bond Adjacent to the Sulfur Atom with a New Activator System, AgNO<sub>3</sub>/KF

Kobayashi, Kei; Sugie, Atsushi; Takahashi, Masabumi; Masui, Kentaro; Mori, Atsunori

doi:10.1021/ol052063y

Cited by 164 publications

(56 citation statements)

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“…The reaction of a thiophene derivative smoothly occurred with aryl iodides in the presence of silver(I) uoride and a catalytic amount of PdCl 2 (PPh 3 ) 2 to afford the corresponding arylated product in a reasonable yield. 9 Oxidative homocoupling in the absence of aryl halide was found to take place to afford the corresponding bithiophene.…”

Section: Introductionmentioning

confidence: 98%

Transition Metal-catalyzed Bond-forming Reactions at the C-H Bond of Heteroaromatic Compounds

Mori

2011

J. Synth. Org. Chem. Jpn.

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Recent progress in the C H coupling reactions of heteroaromatic compounds in our group is summarized. Coupling of thiophene derivatives occurs in the presence of a nickel or palladium catalyst with a base as an additive. Lithium t butoxide and several magnesium amides are effective for the coupling reaction of aryl chlorides, bromides, and iodides. Coupling at the C H bond of thiophene with thienyl halides also occurs smoothly forming a thiophene thiophene bond. The reaction is successfully applied to the polymerization of 2 halo 3 substituted thiophenes leading to highly regioregular head to tail type poly(3 substituted thiophene)s. The reaction of thiazole at the C H bond (2 position) with several secondary amines induces C H, N H coupling with a copper catalyst. J. Synth. Org. Chem., Jpn. 1202In considering the reaction mechanism of thiazoles and thiophenes as shown in Scheme 3, the key for the catalytic reaction would be the palladation reaction at the C H bond. The organopalladium intermediate Aryl Pd Th (Th thiophene) can undergo reductive elimination leading to the arylation product accompanied by the formation of palladium(0). There would be two possible pathways for the formation of Aryl Pd Th: Nucleophilic substitution of a heteroaromatic carbanion, which is formed by proton abstraction, to palladium(II) (path a), or electrophilic attack to palladium and following re aromatization (path b). The former is expected to occur at the acidic C H bond such as the 2 position of thiazole, whereas an electron enriched carbon such as the 5 position of thiazole or the 2 position of thiophene would favor the latter.However, proton abstraction at the less acidic C H bond at the 2 position of thiophene may also be possible if a stronger base is employed and that such new reaction systems may open fresh vistas for the C H functionalization of heteroaromatic compounds. Indeed, this has been recently demonstrated for several coupling reactions with heteroaromatic compounds at various types of C H bonds in the presence of a copper catalyst, in which group I alkoxides, magnesium and zinc amides have been successfully utilized.11 Herewith, our recent efforts on the C H functionalization of thiophene derivatives using relatively stronger bases and transition metal catalysis for the purpose of synthesizing advanced materials with extended π conjugation, and particularly those directed to the preparation of oligothiophenes and polythiophenes are described.On the other hand, it is also important to develop catalytic reactions forming carbon heteroatom bonds as well as the extensively studied carbon carbon bond forming cross coupling reactions. Buchwald Hartwig amination with a nickel or palladium catalyst for the coupling of aromatic halide and amines has been a highly effective protocol to form a carbon nitrogen bond.12 Accordingly, the reaction of amines at a C H bond of heteroaromatic compounds is intriguing as an alternative choice. Our recent efforts concerning a novel C H, N H coupling of azoles using a copper ...

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Section: Introductionmentioning

confidence: 98%

Transition Metal-catalyzed Bond-forming Reactions at the C-H Bond of Heteroaromatic Compounds

Mori

2011

J. Synth. Org. Chem. Jpn.

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“…In a next step we tested a protocol reported by A. Mori et al [42][43][44] who were able to couple 2-bromothiophenes with aryl iodides: the 4'-functionalized 4-iodobiphenyls were reacted with 2-functionalized thiophenes using 5 mol-% [PdCl 2 (PPh 3 ) 2 ], PPh 3 , potassium fluoride, and silver nitrate as the catalytic system to obtain the thiophenylphenylenes in moderate to acceptable yields of 58% (9) and 33% (10) (Scheme 3). Whereas the solubility of 9 is sufficient for purification via column chromatography, 10 was purified by filtering the precipitated product and repeatedly washing with various solvents.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of functionalized thiophene/phenyl co-oligomers by direct arylation of thiophenes

Osadnik¹,

Lützen

Martens³

2014

Arkivoc

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π-Conjugated rod-like molecules have proven to be powerful candidates for the generation of well-defined nanostructures with interesting optical and optoelectrical properties. Their synthesis, however, turns out to be rather complex in some cases. Here, we have optimized the synthesis of oligomers consisting of thiophene and phenylene groups with three or four aromatic units using a direct arylation approach, which allows us to use cheap starting materials and to minimize the number of reaction steps considerably.

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“…Chan and co-workers found that furan (79) and pyrrole (87) (Figure 17) underwent successful direct C-2 arylation with aryl bromides under a nitrogen atmosphere in the presence of 5 mol% Co(II)-A C H T U N G T R E N N U N G (tap) (tap = tetrakis-4-anisylporphirinato dianion), 10 equiv. of KOH and 100 equiv.…”

Section: A C H T U N G T R E N N U N G (Hetero)arylation Of Furan Andmentioning

confidence: 99%

Cross‐Coupling of Heteroarenes by CH Functionalization: Recent Progress towards Direct Arylation and Heteroarylation Reactions Involving Heteroarenes Containing One Heteroatom

et al. 2014

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In recent years, transition metal-catalyzed direct (hetero)arylation reactions of heteroarenes with (hetero)aryl halides and pseudohalides have received significant attention as eco-friendly and economic alternatives to classical methods for the construction of heteroaryl-(hetero)aryl C À C bonds by transition metal-catalyzed cross-couplings involving the use of stoichiometric amounts of organometallic reagents. This critical review with 430 references covers the results obtained in the period January 2009 to February 2013 in the area of the transition metal-catalyzed direct inter-and intramolecular (hetero)arylation reactions of heteroarenes containing one heteroatom. Particular attention has been given to illustrate chemo-and site selectivity aspects of these reactions as well applications of these C À C bond forming reactions in the synthesis of pharmaceutically relevant compounds, natural products and their analogues and precursors. The most recent advancements into the mechanism(s) of these reactions have also been briefly reported.

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Palladium-Catalyzed Coupling Reactions of Bromothiophenes at the C−H Bond Adjacent to the Sulfur Atom with a New Activator System, AgNO₃/KF

Cited by 164 publications

References 26 publications

Transition Metal-catalyzed Bond-forming Reactions at the C-H Bond of Heteroaromatic Compounds

Transition Metal-catalyzed Bond-forming Reactions at the C-H Bond of Heteroaromatic Compounds

Synthesis of functionalized thiophene/phenyl co-oligomers by direct arylation of thiophenes

Cross‐Coupling of Heteroarenes by CH Functionalization: Recent Progress towards Direct Arylation and Heteroarylation Reactions Involving Heteroarenes Containing One Heteroatom

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Palladium-Catalyzed Coupling Reactions of Bromothiophenes at the C−H Bond Adjacent to the Sulfur Atom with a New Activator System, AgNO3/KF

Cited by 164 publications

References 26 publications

Transition Metal-catalyzed Bond-forming Reactions at the C-H Bond of Heteroaromatic Compounds

Transition Metal-catalyzed Bond-forming Reactions at the C-H Bond of Heteroaromatic Compounds

Synthesis of functionalized thiophene/phenyl co-oligomers by direct arylation of thiophenes

Cross‐Coupling of Heteroarenes by CH Functionalization: Recent Progress towards Direct Arylation and Heteroarylation Reactions Involving Heteroarenes Containing One Heteroatom

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Palladium-Catalyzed Coupling Reactions of Bromothiophenes at the C−H Bond Adjacent to the Sulfur Atom with a New Activator System, AgNO₃/KF