Facile Synthesis of NH-Free 5-(Hetero)Aryl-Pyrrole-2-Carboxylates by Catalytic C–H Borylation and Suzuki Coupling

Kanwal, Sehrish; Ann, N. Y.; Fatima, Saman; Emwas, Abdul‐Hamid; Alazmi, Meshari; Gao, Xin; Ibrar, Maha; Saleem, Rahman Shah Zaib; Chotana, Ghayoor Abbas

doi:10.3390/molecules25092106

Cited by 5 publications

(3 citation statements)

References 93 publications

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“…Borylated indoles are of particular interest because they can serve as versatile building blocks for the construction of functional molecules . Recently, transition-metal-catalyzed direct C–H borylation has emerged as a powerful tool for the construction of C–B bonds due to its broad functional group tolerance and substrate scope allowing late-stage functionalization without the use of protecting groups. , The regioselectivity of the C–H functionalization of unprotected indoles, which have seven different sites, is typically driven by electronic effects. Therefore, C–H borylation reactions occur predominantly at the C2 position which contains the most acidic and reactive C–H bond .…”

Section: Introductionmentioning

confidence: 99%

Ni-Catalyzed Traceless, Directed C3-Selective C–H Borylation of Indoles

Tian

Guo

et al. 2020

J. Am. Chem. Soc.

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A highly efficient and general protocol for traceless, directed C3-selective C–H borylation of indoles with [Ni(IMes)2] as the catalyst is reported. Activation and borylation of N–H bonds by [Ni(IMes)2] is essential to install a Bpin moiety at the N-position as a traceless directing group, which enables the C3-selective borylation of C–H bonds. The N-Bpin group which is formed is easily converted in situ back to an N–H group by the oxidative addition product of [Ni(IMes)2] and in situ-generated HBpin. The catalytic reactions are operationally simple, allowing borylation of a variety of substituted indoles with B2pin2 in excellent yields and with high selectivity. The C–H borylation can be followed by Suzuki–Miyaura cross-coupling of the C-borylated indoles in an overall two-step, one-pot process providing an efficient method for synthesizing C3-functionalized heteroarenes.

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Section: Introductionmentioning

confidence: 99%

Ni-Catalyzed Traceless, Directed C3-Selective C–H Borylation of Indoles

Tian

Guo

et al. 2020

J. Am. Chem. Soc.

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“…Our group is interested in the applications of iridium-catalyzed borylation and Suzuki coupling in organic synthesis. ,− In 2016, we described the application of this methodology to functionalize 2,6-bis(trifluoromethyl)pyridine . Herein, we describe the application of iridium-catalyzed borylation to various trifluoromethyl-substituted pyridines.…”

Section: Introductionmentioning

confidence: 99%

Iridium-Catalyzed C–H Borylation of CF₃-Substituted Pyridines

et al. 2022

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Iridium-catalyzed C–H borylation of CF 3 -substituted pyridines is described in this paper. The boronic ester group can be installed on the α, β, or γ position of pyridine by an appropriate substitution pattern. Sterically governed regioselectivity provides convenient access to a variety of CF 3 -substituted pyridylboronic esters. These catalytic C–H borylation reactions were carried out neatly without the use of any solvent. Several functional groups, such as halo, ester, alkoxy, amino, etc., are compatible with this methodology. These pyridylboronic esters are amenable to column chromatography and the products were isolated in good to excellent yields. α-Borylated pyridines, although isolated in good yields, do not have a long shelf life. The boronic ester derivatives of these CF 3 -substituted pyridines can serve as useful precursors in the synthesis regime.

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“…Interestingly, the coupling reaction takes place selectively at the carbon–halogen bond allowing the preparation of novel alkynyl boron reagents. In a related article, Chotana et al report a sequential iridium-catalyzed borylation of NH-free pyrroles followed by a Suzuki-Miyaura reaction [ 30 ].…”

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confidence: 99%