Catalyst-controlled site-selective N–H and C3-arylation of carbazole <i>via</i> carbene transfer reactions

Bera, Sourav Sekhar; Bahukhandi, Srishti Ballabh; Empel, Claire; Koenigs, René M.

doi:10.1039/d1cc01863a

Cited by 21 publications

(8 citation statements)

References 56 publications

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“…We identified 40 journal articles for direct arylation with a total of 42 reactions, which were appropriate for data extraction (Figure ). ,,− 18 of these make use of 5 mol % (pre)catalyst (42% of the total for this set), and 24% contain the 0–1 mol % category; the remaining reactions make up the rest (32%). There is a large variation in the ppm levels in the 5 mol % category from the lowest value of 109 to 2800 ppm, and the an average is 998 ppm.…”

Section: Direct Arylationmentioning

confidence: 92%

Pd-Catalyzed Cross-Couplings: On the Importance of the Catalyst Quantity Descriptors, mol % and ppm

Horbaczewskyj

Fairlamb

2022

Org. Process Res. Dev.

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This Review examines parts per million (ppm) palladium concentrations in catalytic cross-coupling reactions and their relationship with mole percentage (mol %). Most studies in catalytic cross-coupling chemistry have historically focused on the concentration ratio between (pre)catalyst and the limiting reagent (substrate), expressed as mol %. Several recent papers have outlined the use of “ppm level” palladium as an alternative means of describing catalytic cross-coupling reaction systems. This led us to delve deeper into the literature to assess whether “ppm level” palladium is a practically useful descriptor of catalyst quantities in palladium-catalyzed cross-coupling reactions. Indeed, we conjectured that many reactions could, unknowingly, have employed low “ppm levels” of palladium (pre)catalyst, and generally, what would the spread of ppm palladium look like across a selection of studies reported across the vast array of the cross-coupling chemistry literature. In a few selected examples, we have examined other metal catalyst systems for comparison with palladium.

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Section: Direct Arylationmentioning

confidence: 92%

Pd-Catalyzed Cross-Couplings: On the Importance of the Catalyst Quantity Descriptors, mol % and ppm

Horbaczewskyj

Fairlamb

2022

Org. Process Res. Dev.

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“…The active carbene exhibits strong reactivity toward R–H (R = C, − N, , O, S, and B , ) bonds under mild conditions (Scheme B). The diazo and diazirine moiety can be activated thermally, − photochemically, − or under transition-metal-catalyzed conditions, , forming active carbenes to react with organic substrates by R–H activation and insertion.…”

Section: Introductionmentioning

confidence: 99%

Carbene-Mediated Polymer Cross-Linking with Diazo Compounds by C–H Activation and Insertion

Yang

Yun

et al. 2022

Macromolecules

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Compared with linear thermoplastic polymers, thermoset polymers with three-dimensional network structures exhibit improved solvent tolerance, heat resistance, and mechanical strength. The radicalmediated process is widely used to cross-link the linear polymer chains; however, this process requires high temperature (>150 °C) or UV irradiation to generate highly energetic radicals, unavoidably leading to undesired side reactions and uncontrolled cross-linking behavior. This work proposes and achieves a carbene-mediated polymer cross-linking with diazo-based compounds by C−H activation and an insertion mechanism under relatively mild conditions. A simple route containing only one or two steps is established to synthesize three generations of diazo-based cross-linkers 1G, 2G, and 3G. The cross-linker 1G exhibits the lowest cross-linking efficiency due to the undesired self-coupling of carbenes. After optimizing the chemical structure and increasing the numbers of diazo moieties, the cross-linking efficiency significantly improves for 2G and 3G cross-linkers. These cross-linkers are applicable for any polymers containing C−H bonds. They are useful in a wide range of applications, from the adhesion of low surface energy ultrahigh molecular weight polyethylene (UHMWPE) to polymer modification by co-cross-linking. This versatile, convenient, and practical carbene-mediated cross-linking strategy provides new opportunities for modification, cross-linking, and adhesion in polymer science.

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“…Various metal‐carbenoid intermediates have found wide applications in synthetic chemistry due to their unique reactivities [15–32] . In this regard, the aromatic C( sp 2 )−H functionalization of electron‐rich aromatics with metal carbenes generated from diazo compounds has attracted considerable attention, and transition metal catalysts based on Rh, [33–44] Au, [45–55] Cu, [56–58] and Fe, [59–63] etc, have been developed for these valuable transformations (Scheme 1a,i) [64–70] . However, so far most of the protocols are still confined to reactions between two reactants with limited synthetic efficiency (Scheme 1a).…”

Section: Introductionmentioning

confidence: 99%

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

Lü

Teng

et al. 2022

Chemistry A European J

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A three‐component reaction of N, N‐disubstituted aniline, α‐diazo ester, and an allylic electrophile has been realized by [Rh(II)]2/Xantphos catalysis, providing a direct access to various aniline derivatives bearing diaryl allylic quaternary centers in good yields. The synthetic utility of this protocol was demonstrated by facile derivatization of the products for preparation of biologically relevant molecules and structural scaffolds, which offers a high potential for increasing the molecular diversity. Mechanistic studies identified α, α‐diarylacetate species as an active intermediate, thereby revealing the presence of a C(sp2)−H functionalization of aniline derivatives/allylic alkylation cascade in this attractive catalytic transformation.

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Catalyst-controlled site-selective N–H and C3-arylation of carbazole via carbene transfer reactions

Abstract: A site-selective direct arylation reaction of carbazole and other N-heterocycles with diazo-naphthalen-2(1H)-ones has been developed. While Au(I)-NHC catalysts lead to selective C3-arylation, palladium acetate allows for selective N-H arylation, displaying...

Cited by 21 publications

References 56 publications

Pd-Catalyzed Cross-Couplings: On the Importance of the Catalyst Quantity Descriptors, mol % and ppm

Pd-Catalyzed Cross-Couplings: On the Importance of the Catalyst Quantity Descriptors, mol % and ppm

Carbene-Mediated Polymer Cross-Linking with Diazo Compounds by C–H Activation and Insertion

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

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