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

Tian, Yaming; Guo, Xiaoning; Wu, Zhu; Friedrich, Alexandra; Westcott, Stephen A.; Braunschweig, Holger; Radius, Udo; Marder, Todd B.

doi:10.1021/jacs.0c05434

Cited by 65 publications

(37 citation statements)

References 109 publications

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“…Another traceless strategy for the C3−H borylation of indoles was reported by Marder and co‐workers (Scheme 6). [15] These researchers discovered a method of adding a modifiable Bpin moiety to NH ‐indoles using [Ni(IMes)] 2 as a catalyst at 10 mol% loading with 1.5 equivalents of B 2 pin 2 . This resulted in up to 79% yield of C3‐borylated indoles while tolerating both electron‐withdrawing and electron‐donating groups.…”

Section: Functionalization At the C3 Positionmentioning

confidence: 99%

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Recent Advances in Metal‐Catalyzed Functionalization of Indoles

et al. 2021

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Indole is one of the most important heterocycles in organic synthesis, natural products, and drug discovery. Recently, tremendous advances in the selective functionalization of indoles have been reported. Although the most important advances have been powered by transition metal catalysis, exceedingly useful methods in the absence of transition metals have also been reported. In this review, we provide an overview of functionalization reactions of indoles that have been published in the last years with a focus on the most recent advances, aims, and future trends. The review is organized by the positional selectivity and type of methods used for functionalization. In particular, we discuss major advances in transition‐metal‐catalyzed C−H functionalization at the classical C2/C3 positions, transition‐metal‐catalyzed C−H functionalization at the remote C4/C7 positions, transition‐metal‐catalyzed cross‐coupling, and transition‐metal‐free functionalization.

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Section: Functionalization At the C3 Positionmentioning

confidence: 99%

“… Traceless C3−H borylation of indoles by Marder [15] …”

Section: Functionalization At the C3 Positionmentioning

confidence: 99%

Recent Advances in Metal‐Catalyzed Functionalization of Indoles

et al. 2021

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“…[23] Very recently, we reported an efficient [Ni(IMes) 2 ]catalyzed directed C3-selective CÀ H borylation of indoles. [24] In 2006, Hosoya [25a] and Yorimitsu [25b] independently demonstrated the borylation of aryl sulfides employing rhodium and palladium-NHC catalysts, respectively. Yorimitsu's group continued to develop the borylation of diaryl sulfoxides using a phosphine-ligated palladium catalyst and LiN(SiMe 3 ) 2 as the base.…”

Section: Introductionmentioning

confidence: 99%

“…Subsequently, by applying a readily prepared NHC‐stabilized nickel(0) catalyst precursor [Ni 2 (ICy) 4 { μ ‐( η 2 : η 2 )‐COD}] (ICy=1,3‐dicyclohexylimidazolin‐2‐ylidene) and the base NaOAc, we demonstrated the catalytic C−Cl borylation of aryl chlorides [23] . Very recently, we reported an efficient [Ni(IMes) 2 ]‐catalyzed directed C3‐selective C−H borylation of indoles [24] . In 2006, Hosoya [25a] and Yorimitsu [25b] independently demonstrated the borylation of aryl sulfides employing rhodium and palladium‐NHC catalysts, respectively.…”

Section: Introductionmentioning

confidence: 99%

Ni‐Catalyzed Borylation of Aryl Sulfoxides

Huang

Krebs

et al. 2021

Chemistry A European J

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A nickel/N-heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B 2 (neop) 2 (neop = neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electrondeficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni-catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4-(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans-[Ni(ICy) 2 (4-CF 3 -C 6 H 4 ){(SO)-4-MeO-C 6 H 4 }] 4. For complex 5, the isomer trans-[Ni-(ICy) 2 (C 6 H 5 )(OSC 6 H 5 )] 5-I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans-[Ni-(ICy) 2 (C 6 H 5 )(OSC 6 H 5 )] 5-I is in equilibrium with the S-bonded isomer trans-[Ni(ICy) 2 (C 6 H 5 )(SOC 6 H 5 )] 5, as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2-TZVP-level of theory) and connected via a transition state trans-[Ni-(ICy) 2 (C 6 H 5 )(η 2 -{SO}-C 6 H 5 )], which lies only 10.8 kcal/mol above 5.

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“…[6] Especially for C3-substituted pyrroles, the selectivity of the C2 and C5 positions constitutes a prototypical example of such an issue. As one of the most notable advances in CÀH functionalization, CÀH borylation [7] has been conducted with pyrroles [5a, 8] by transition metal catalysis. [9] To the best of our knowledge, only one example of the C À H borylation of a C3substituted pyrrole containing an ester group has been recently reported with an iridium catalyst, in which the regioselectivity is preferentially located at the less hindered C5 position (Figure 1 a).…”

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confidence: 99%

Metal‐Free Directed C−H Borylation of Pyrroles

Wang

Chen

et al. 2021

Angewandte Chemie

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Robust strategies to enable the rapid construction of complex organoboronates in selective, practical, low-cost, and environmentally friendly modes remain conspicuously underdeveloped. Here, we develop a general strategy for the siteselective C À H borylation of pyrroles by using only BBr 3 directed by pivaloyl groups, avoiding the use of any metal. The site-selectivity is generally dominated by chelation and electronic effects, thus forming diverse C2-borylated pyrroles against the steric effect. The formed products can readily engage in downstream transformations, enabling a step-economic process to access drugs such as Lipitor. DFT calculations (wB97X-D) demonstrate the preferred positional selectivity of this reaction.

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

Cited by 65 publications

References 109 publications

Recent Advances in Metal‐Catalyzed Functionalization of Indoles

Recent Advances in Metal‐Catalyzed Functionalization of Indoles

Ni‐Catalyzed Borylation of Aryl Sulfoxides

Metal‐Free Directed C−H Borylation of Pyrroles

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