On water direct arylation of imidazo[1,2- a ]pyridines with aryl halides

We report herein, for the first time, the direct C–H bond arylation of imidazo[1,2-a]pyridine with aryl halides using monodisperse Ni@Pd core@shell nanoparticles assembled on reduced graphene oxide (rGO) as a highly efficient and reusable heterogeneous catalyst. Monodisperse Ni@Pd core@shell nanoparticles (NPs) were synthesized by using one-pot successive reduction of metal precursors in the presence of oleylamine and trioctyl phosphine and then assembled on rGO via a liquid-phase self-assembly method to yield rGO-Ni@Pd nanocatalyst. The structures of the colloidal Ni@Pd core@shell NPs and rGO-Ni@Pd nanocatalyst were characterized by TEM, high-resolution TEM (HR-TEM), STEM-EDS, XPS, and ICP-MS. Next, rGO-Ni@Pd nanocatalysts as well as rGO-Ni and rGO-Pd counterparts were first tested in the direct C–H bond arylation of imidazo[1,2-a]pyridine with bromobenzene under tunable reaction conditions to find the optimum reaction conditions. Under the optimum reaction conditions, the substrate scope of rGO-Ni@Pd-catalyzed direct C–H arylation of imidazo[1,2-a]pyridine was examined by performing the catalytic reactions with a variety of aryl halides. These studies showed for the first time that rGO-Ni@Pd nanocatalysts are highly efficient and reusable catalysts in the direct C–H bond arylation reactions and have a high potential to be applied in other C–H activation reactions.

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“…(See ref .) Yellow solid, 249 mg from 1-iodo-4-(trifluoromethyl)benzene (95% yield, 20:80 EtOAc/hexane).…”

Section: Methodsmentioning

confidence: 99%

Monodisperse Ni@Pd Core@Shell Nanoparticles Assembled on Reduced Graphene Oxide as a Highly Efficient and Reusable Heterogeneous Catalyst for the C–H Bond Arylation of Imidazo[1,2-a]pyridine with Aryl Halides

Kılıç

Turgut

Sevim

et al. 2018

ACS Sustainable Chem. Eng.

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“…Functionalization of imidazo[1, 2‐ a ]pyridine directly in water medium was reported by Kalari et.al .in 2017 (Scheme 18). [46] This on‐water arylation at C‐3 of imidazo[1, 2‐ a ]pyridine was carried out with aryl halide (−I, −Cl, −Br) using Pd salt. Aryl iodides containing electron‐donating groups furnish good yields as compared to that of electron‐withdrawing groups.…”

Section: Functionalization Reactions Of Imidazo[1 2‐a]pyridinementioning

confidence: 99%

Recent Developments in Transition‐Metal‐Catalyzed Regioselective Functionalization of Imidazo[1, 2‐a]pyridine

Konwar

Bora

2021

ChemistrySelect

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Imidazo[1,2‐a]pyridine is an important nitrogen‐containing heterocycle from biological as well as pharmaceutical point of view. In recent years, regioselective functionalization of C−H bond of imidazo[1,2‐a]pyridine is extensively carried out using various transition metal‐based catalysts. Alkenylation, arylation, dual dehydrogenative annulations, formylation, thiolation, aminomethylation, dicarbonylation, phosphonylation along with other significant reactions are the progress in the field of functionalization of imidazopyridine. Most of these functionalizations are done at the C‐3 position of imidazo[1,2‐a]pyridine scaffold and in addition to that development towards C‐5 regioselectivity is also available. In this review, our aim is to present the recent advances for the functionalization of imidazo[1,2‐a]pyridine employing transition metal catalysts under significant reaction conditions.

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“…A ligand‐free palladium catalysed on water method was used for the direct arylation of imidazo[1,2‐ a ]pyridines with aryl halides . The reaction proceeded well with Pd(OAc) 2 (5 mol%) and KOH base at 100 °C during 24 h (Scheme ).…”

Section: Direct Functionalisation Reactionsmentioning

confidence: 99%

Recent Advances and Prospects of Organic Reactions “On Water”

et al. 2019

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Organic reactions “On water” is a rapidly developing area over the past few years. Many important classes of reactions like cross‐coupling reactions, pericyclic reactions, C−H activations etc. were performed on water and have shown tremendous increase in the reaction rates due to the potential hydrogen bonding capacity of water. This review focuses on the recent trends and developments in the field of on water reactions applied to organic synthesis and covers literature from 2016–2019.

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On water direct arylation of imidazo[1,2- a ]pyridines with aryl halides

Cited by 24 publications

References 48 publications

Monodisperse Ni@Pd Core@Shell Nanoparticles Assembled on Reduced Graphene Oxide as a Highly Efficient and Reusable Heterogeneous Catalyst for the C–H Bond Arylation of Imidazo[1,2-a]pyridine with Aryl Halides

Monodisperse Ni@Pd Core@Shell Nanoparticles Assembled on Reduced Graphene Oxide as a Highly Efficient and Reusable Heterogeneous Catalyst for the C–H Bond Arylation of Imidazo[1,2-a]pyridine with Aryl Halides

Recent Developments in Transition‐Metal‐Catalyzed Regioselective Functionalization of Imidazo[1, 2‐a]pyridine

Recent Advances and Prospects of Organic Reactions “On Water”

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