N-Heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed C H bond arylation of (benzo)thiophenes with aryl chlorides

Yin, Shun-Chao; Zhou, Quan; He, Qian-Wei; Li, Shu-Wan; Qian, Peng‐Cheng; Shao, Li‐Xiong

doi:10.1016/j.tet.2016.11.053

Cited by 17 publications

(7 citation statements)

References 51 publications

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“…1 While conventional cross-couplings are still widely used, 2 direct C–H arylation has emerged over the last two decades as a powerful approach that eliminates the need for prefunctionalization, thus leading to shorter synthetic routes. The direct C2-arylation of benzo[ b ]thiophene was first demonstrated by Ohta in 1990, 3 and over the past decade several further examples have been reported using Pd, 4 Cu, 5 or Ir 6 as catalysts. 7 However, all the methodologies reported require the use of elevated temperatures (100–150 °C), which limits their functional group compatibility.…”

Section: Introductionmentioning

confidence: 99%

Ag(I)–C–H Activation Enables Near-Room-Temperature Direct α-Arylation of Benzo[b]thiophenes

et al. 2018

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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 Pd(dba)·CHCl 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.

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Section: Introductionmentioning

confidence: 99%

Ag(I)–C–H Activation Enables Near-Room-Temperature Direct α-Arylation of Benzo[b]thiophenes

et al. 2018

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“…In another report, Yin et al examined the direct C–H arylation of benzo[ b ]thiophene using catalytic Pd(II) and aryl chlorides to form 2-aryl benzo[ b ]thiophene derivatives. 14 In a similar report, Chen and coworkers utilized a Pd-catalyzed coupling/cyclization reaction of 2-iodothiophenols with terminal alkynes to achieve 2-aryl substituted benzo[ b ]thiophene derivatives in moderate to high yields with fluoro-, chloro- and trifluoromethyl-substituted 5 and 6 positions. 15 Yamauchi and coworkers introduced the multicomponent arylation/cyclization of 2-alkynylthioanisoles to furnish 2,3-diarylated benzo[ b ]thiophene derivatives in a single step using a Pd/phenanthroline catalyst.…”

Section: Introductionmentioning

confidence: 99%

Sodium halides as the source of electrophilic halogens in green synthesis of 3-halo- and 3, n -dihalobenzo[ b ]thiophenes

et al. 2018

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A convenient methodology for the synthesis of mono- and di-halogenated benzo[b]thiophenes is described herein, which utilizes copper(II) sulfate pentahydrate and various sodium halides in the presence of substituted 2-alkynylthioanisoles. The proposed method is facile, uses ethanol as a green solvent, and results in uniquely substituted benzo[b]thiophene structures with isolated yields up to 96%. The most useful component of this methodology is the selective introduction of bromine atoms at every available position (2–7) around the benzo[b]thiophene ring, while keeping position 3 occupied by a specific halogen atom such as Cl, Br or I. Aromatic halogens are useful reactive handles; therefore, the selective introduction of halogens at specific positions would be valuable in the targeted synthesis of bioactive molecules and complex organic materials via metal-catalyzed cross coupling reactions. This work is a novel approach towards the synthesis of dihalo substituted benzo[b]thiophene core structures, which provides a superior alternative to the current methods discussed herein.

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“…2‐(4‐Methoxyphenyl)‐5‐phenylthiophene (5a): The product was obtained as yellow solid in 80 % yield. 1 H NMR (300 MHz, CDCl 3 ): δ = 3.83 (s, 3 H), 6.92 (d, J = 8.7 Hz, 2 H), 7.16 (d, J = 3.6 Hz, 1 H), 7.24–7.27 (m, 2 H), 7.39 (t, J = 7.5 Hz, 2 H), 7.56 (d, J = 8.7 Hz, 2 H), 7.61 (d, J = 7.5 Hz, 2 H) ppm.…”

Section: Methodsmentioning

confidence: 99%

One‐Pot Synthesis of Unsymmetrical 1,3‐Butadiyne Derivatives and their Application in the Synthesis of Unsymmetrical 2,5‐Diarylthiophenes

et al. 2018

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A one‐pot protocol was developed for the synthesis of unsymmetrical 1,3‐butadiynes. The procedure is based on two sequential reactions: deprotection of R–C≡C–C≡C–C(Me)2OH derivatives in a retro‐Favorskii reaction to furnish a terminal 1,3‐butadiyne compound, which reacted with aryl iodides in a Sonogashira‐type cross‐coupling reaction catalyzed by Pd(PPh3)4 and CuI, using TBAOH as activator and toluene as solvent under reflux for 10 min. We also studied in situ thiocyclization of 1,3‐butadiynes, leading to unsymmetrical 2,5‐diarylthiophenes. The principal features of this method are operational simplicity, good substrate scope, very fast reaction, and high yields.

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N-Heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed C H bond arylation of (benzo)thiophenes with aryl chlorides

Cited by 17 publications

References 51 publications

Ag(I)–C–H Activation Enables Near-Room-Temperature Direct α-Arylation of Benzo[b]thiophenes

Ag(I)–C–H Activation Enables Near-Room-Temperature Direct α-Arylation of Benzo[b]thiophenes

Sodium halides as the source of electrophilic halogens in green synthesis of 3-halo- and 3, n -dihalobenzo[ b ]thiophenes

One‐Pot Synthesis of Unsymmetrical 1,3‐Butadiyne Derivatives and their Application in the Synthesis of Unsymmetrical 2,5‐Diarylthiophenes

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