O<sub>2</sub>-Mediated Te(II)-Redox Catalysis for the Cross-Dehydrogenative Coupling of Indoles

Cremer, Christopher; Patureau, Frédéric W.

doi:10.1021/jacsau.2c00193

Cited by 10 publications

(9 citation statements)

References 59 publications

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“…Scheme 5 The O2-mediated Te(II)-redox catalysis for the cross dehydrogenative coupling of indoles. 56 In conclusion, phenotellurazines PTeZ1 and PTeZ2 outperform the herein optimized best Te-free organo-catalyst, cat14, in both considered benchmark cross dehydrogenative coupling reactions. Thus, the catalytic role of tellurium cannot be satisfyingly mimicked by any light atom organic structure in our hands.…”

Section: Synlettmentioning

confidence: 76%

“…However, cat14 was found completely inactive in another benchmark cross dehydrogenative coupling reaction recently reported by us to operate under PTeZ1 or PTeZ2 catalysis, which involves indole substrates (Scheme 5). 56 In that previous study, control experiments were also conducted in order to rule out catalytically active impurities. Therefore, while cat14 yielded interesting catalytic properties in the present study, it seems that the phenotellurazine scaffold Template for SYNLETT Thieme features a broader scope in the herein investigated oxidative coupling reactions.…”

Section: Synlettmentioning

confidence: 99%

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Aromatic Amine Catalysts for the O2-Mediated Cross-Dehydrogenative Phenothiazination Reaction?

Patureau,

Nandi,

Paffen

2023

Synlett

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Metal-free aromatic amines have been utilized recently as redox-active catalysts in various oxidative coupling reactions. In this study, we investigated a series of aromatic amines and their potential redox catalytic activity, in particular compared to our previously reported amino-Te(II) catalysts. The O2 mediated cross dehydrogenative phenothiazination of phenols was utilized as a benchmark test reaction, as well as the O2 mediated cross dehydrogenative coupling of indoles. We thus identified a proton sponge (cat14) as an effective aromatic amine redox catalyst. It was moreover found that although the proton sponge displays clear catalytic activity, it is generally less active than previously reported phenotellurazine catalysts. The insights provided by this study should guide future research efforts for the development of innovative redox catalyzed cross dehydrogenative coupling reactions.

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Section: Synlettmentioning

confidence: 76%

Section: Synlettmentioning

confidence: 99%

Aromatic Amine Catalysts for the O2-Mediated Cross-Dehydrogenative Phenothiazination Reaction?

Patureau,

Nandi,

Paffen

2023

Synlett

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“…The EPR studies were carried out to confirm whether the reaction follows a radical path due to the low oxidation potential of the tellurium. Divalent organotelluriums have been used as catalysts for cross‐dehydrogenative coupling [11c,g] and explored as antioxidants [33] for radical quenching activities. These reactions involve one‐electron oxidation of Te(II) to form Te(III) radical species under oxidative conditions and form tellurium radical, which was confirmed by EPR.…”

Section: Resultsmentioning

confidence: 99%

2‐Benzamide Tellurenyl Iodides: Synthesis and Their Catalytic Role in CO₂ Mitigation

Jain

Batabyal

Thorat

et al. 2023

Chemistry A European J

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Benzamide-derived organochalcogens (chalcogen = S, Se, and Te) have shown promising interest in biological and synthetic chemistry. Ebselen molecule derived from benzamide moiety is the most studied organoselenium. However, its heavier congener organotellurium is under-explored. Here, an efficient copper-catalyzed atom economical synthetic method has been developed to synthesize 2-phenyl-benzamide tellurenyl iodides by inserting a tellurium atom into carbon-iodine bond of 2iodobenzamides in one pot with 78-95 % yields. Further, the Lewis acidic nature of Te center and Lewis basic nature of nitrogen of the synthesized 2-Iodo-N-(quinolin-8-yl)benzamide tellurenyl iodides enabled them as pre-catalyst for the activation of epoxide with CO 2 at 1 atm for the preparation of cyclic carbonates with TOF and TON values of 1447 h À 1 and 4343, respectively, under solvent-free conditions. In addition, 2-iodo-N-(quinolin-8-yl)benzamide tellurenyl iodides have also been used as pre-catalyst for activating anilines and CO 2 to form a variety of 1,3-diaryl ureas up to 95 % yield. The mechanistic investigation for CO 2 mitigation is done by 125 Te NMR and HRMS studies. It seems that the reaction proceeds via formation of catalytically active TeÀ N heterocycle, an ebtellur intermediate which is isolated and structurally characterized.

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“…Because anion–π catalysis was so impactful, the integration of unorthodox interactions into catalysis was continued with chalcogen bonds in 2017, [9] followed by pnictogen bonds in 2018 [10] . Since then, chalcogen‐ and pnictogen‐bonding catalysis have received increasing attention in the community [11–39] …”

Section: Figurementioning

confidence: 99%

Pnictogen‐Bonding Catalysts, Compared to Tetrel‐Bonding Catalysts: More Than Just Weak Lewis Acids

Chen

Frontera

López

et al. 2022

Helvetica Chimica Acta

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A hyperresponsive tool to assess supramolecular catalysis, the cyclization of di-epoxides into cyclic ethers is used to elucidate the difference between pnictogen-bonding and Lewis acid catalysis systematically. For all stereoisomers, most tested catalysts follow the Baldwin rules. Brønsted acid and anion-π catalysis afford almost only Baldwin products. Lewis acids such as SbCl 3 , BF 3 and BiCl 3 give the poorest selectivity, with at least 50 % Baldwin (B) products for all stereoisomers. In clear contrast, optimized pnictogen-bonding catalysts operating on the Sb(III) and the Sb(V) level give the fused anti-Baldwin (A) bicycles as the main product of trans epoxides, independent of syn or anti relation of the two epoxides. In the cis series, Sb(III) pnictogen-bonding catalysts afford BA products almost exclusively for syn diastereomers, while anti diastereomers give equal amounts of BA and AB products. Sb(V) pnictogen-bonding catalysts show similarly special trends. These unique characteristics support that pnictogen-bonding catalysis differs from Lewis acid catalysis and can arguably be defined as its non-covalent counterpart, just like hydrogen-bonding catalysis is understood and appreciated as the noncovalent counterpart of Brønsted acid catalysis. Computational studies on the origin of anti-Baldwin selectivity reveal Sb(V) catalysts with an introvert deep σ hole surrounded by an almost planar ring of ligands. Central pnictogen-bond attraction against peripheral steric repulsion then forces the epoxide to break open. In contrast, transient antimony oxidation in cyclic intermediates accounts for the chemoselectivity of Sb(III) catalysts. Presumably due to insufficient accessibility of their σ holes, the activity of tetrel-bonding catalysts is negligible. The division between powerful pnictogen-bonding and irrelevant tetrel-bonding catalysts does not exist with the respective orthodox Lewis acids and thus supports that σ-hole and Lewis acid catalysis are not the same.

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O₂-Mediated Te(II)-Redox Catalysis for the Cross-Dehydrogenative Coupling of Indoles

Cited by 10 publications

References 59 publications

Aromatic Amine Catalysts for the O2-Mediated Cross-Dehydrogenative Phenothiazination Reaction?

Aromatic Amine Catalysts for the O2-Mediated Cross-Dehydrogenative Phenothiazination Reaction?

2‐Benzamide Tellurenyl Iodides: Synthesis and Their Catalytic Role in CO₂ Mitigation

Pnictogen‐Bonding Catalysts, Compared to Tetrel‐Bonding Catalysts: More Than Just Weak Lewis Acids

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O2-Mediated Te(II)-Redox Catalysis for the Cross-Dehydrogenative Coupling of Indoles

Cited by 10 publications

References 59 publications

Aromatic Amine Catalysts for the O2-Mediated Cross-Dehydrogenative Phenothiazination Reaction?

Aromatic Amine Catalysts for the O2-Mediated Cross-Dehydrogenative Phenothiazination Reaction?

2‐Benzamide Tellurenyl Iodides: Synthesis and Their Catalytic Role in CO2 Mitigation

Pnictogen‐Bonding Catalysts, Compared to Tetrel‐Bonding Catalysts: More Than Just Weak Lewis Acids

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Product

Resources

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O₂-Mediated Te(II)-Redox Catalysis for the Cross-Dehydrogenative Coupling of Indoles

2‐Benzamide Tellurenyl Iodides: Synthesis and Their Catalytic Role in CO₂ Mitigation