Chemo- and enantioselective hetero-coupling of hydroxycarbazoles catalyzed by a chiral vanadium(<scp>v</scp>) complex

Sako, M.; Higashida, Keigo; Kamble, Ganesh Tatya; Kaut, Kevin P.; Kumar, Ankit; Hirose, Yuta; Zhou, Da‐Yang; Suzuki, Takeyuki; Rueping, Magnus; Maegawa, Tomohiro; Takizawa, Shinobu; Sasai, Hiroaki

doi:10.1039/d1qo00783a

Cited by 22 publications

(24 citation statements)

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“…The intermediate can convert into radical intermediate B, which contains vanadium( iv ), via one-electron oxidation; this is because the oxidation potential of 1a is lower than that of 2a (based on cyclic voltammogram in MeCN with Bu 4 NPF 6 : E 1a (ox) = 0.45 V ( vs. Fc/Fc + ) and E 2a (ox) = 0.93 V ( vs. Fc/Fc + )). 11 Subsequently, its C–C bond formation 16 with 2a gives C. Finally, oxidation by molecular oxygen and rearomatization complete the catalytic cycle with the regeneration of V-MPS4 and/or A, releasing 3aa as the product. The formation of a vanadium( iv ) species was confirmed by electron spin resonance (ESR) analysis of V-MPS4 after performing the CDC reaction under a nitrogen atmosphere ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“… 10 Moreover, no CDC reaction of hydroxycarbazoles mediated by heterogeneous oxovanadium catalysts has been reported so far. 11 The use of heterogeneous catalysts for this reaction would be advantageous in terms of reuse and handling. In addition, that would also be effective in avoiding unnecessary contact between the product and the catalyst to address its over-oxidation issue.…”

Section: Introductionmentioning

confidence: 99%

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Chemo- and regioselective cross-dehydrogenative coupling reaction of 3-hydroxycarbazoles with arenols catalyzed by a mesoporous silica-supported oxovanadium

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemo- and regioselective cross-dehydrogenative coupling reaction of 3-hydroxycarbazoles with arenols catalyzed by a mesoporous silica-supported oxovanadium

et al. 2021

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“…In 2021, Sasai and co-workers reported that vanadium catalysts were highly effective in cross-coupling naphthols with hydroxylcarbazole (Scheme ). This oxidative coupling through a monomeric vanadium catalyst afforded both good enantioselectivity and yield, establishing the feasibility of using vanadium catalysts in enantioselective oxidative heterocoupling reactions.…”

Section: Discussionmentioning

confidence: 99%

Catalytic Oxidative Coupling of Phenols and Related Compounds

Kozlowski

2022

ACS Catal.

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Phenols and their derivatives are the elementary building blocks for several classes of complex molecules that play essential roles in biological systems. Nature has devised methods to selectively couple phenolic compounds, and many efforts have been undertaken by chemists to mimic such coupling processes. A range of mechanisms can be involved, and with well-studied catalysts, reaction outcomes in phenol−phenol oxidative coupling reactions can be predicted with a good level of fidelity. However, reactions with catalysts that have not been studied or that do not behave similarly to known catalysts can be hard to predict and control. This Perspective provides an overview of catalytic methods for the oxidative coupling of phenols, focusing on the last 10 years, and summarizes current challenges.

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“…Chem. Front.2021848784885 . This paper describes the chiral vanadium complex-catalyzed oxidative heterocoupling of hydroxycarbazole for the first time.…”

Section: Key Referencesmentioning

confidence: 99%

“…A further advantage of the vanadium-catalyzed couplings is that neither a bulky substituent nor a directing group at the 3-position of 1 is required for high asymmetric induction, unlike the couplings using Cu(II) ,,− and Fe(III) ,, metal catalysts; however, Zhang et al, Pappo et al, and Ishihara et al developed chiral iron and copper complexes with ligands such as phosphoric acid, diphosphine oxide, and picolinic acid for the coupling reactions of 1 with no substitution at the 3-position. As numerous comprehensive reviews on the development of enantioselective oxidative coupling of 2-naphthols and their applications have been previously published, in this Account, we focus on the recent advances in oxidative couplings that used chiral vanadium complexes to afford biresorcinols, polycyclic biphenols, oxa[9]helicenes, bi(hydroxycarbazole)s, ,, and C 1 -symmetrical biarenols …”

Section: Introductionmentioning

confidence: 99%

Atroposelective Synthesis of C–C Axially Chiral Compounds via Mono- and Dinuclear Vanadium Catalysis

2022

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Conspectus Axially chiral compounds with rotationally constrained σ-bonds that exhibit atropisomerism are lucrative synthetic targets because of their ubiquity in functional materials and natural products. The metal complex-catalyzed enantioselective fabrication of axially chiral scaffolds has been widely investigated, and thus far, considerable progress has been made. Over the past two decades, we have developed a highly efficient strategy for constructing axially chiral biarenol derivatives using chiral mono- and dinuclear vanadium complexes. These complexes are readily prepared from vanadium(IV) salts and Schiff base ligands (generated from the condensation of (S)-tert-leucine and di- or monoformyl-(R)-1,1′-bi-2-naphthol (BINOL) derivatives) under O2 and act as highly active catalysts for highly stereoselective C–C bond formation. In particular, the vanadium complex-catalyzed enantioselective oxidative coupling of 2-naphthols 1 under oxygen or in air, which is a green oxidant, affords the desired axially chiral molecules in high yields and high stereoselectivity (up to quantitative yield and 97% ee), along with water as the sole coproduct. This coupling reaction tolerated various functional groups (such as halogens, alkoxys, and boryls) and avoided overoxidation of coupling products. The key feature of dinuclear vanadium(V) catalysts such as (R a,S,S)-5a is an outstanding mode of the homocoupling reaction, in which a single molecule of the catalyst activates two molecules of the starting material (e.g., 2-naphthols) simultaneously. With this “dual activation” mechanism, the oxidative coupling promoted by the dinuclear catalyst proceeds in an intramolecular manner. The homocoupling rate using 5 mol % of the dinuclear vanadium(V) complex (R a ,S,S)-5a was measured to be 111 times faster than that of the mononuclear vanadium(IV) complex (S)-4a bearing a half motif of the dinuclear vanadium complex. In the case of the heterocoupling reaction utilizing two different kinds of arenol derivatives, only a starting arenol having lower oxidation potential seems to be activated by the mononuclear vanadium complex. The reaction rate of the heterocoupling using either mono- or dinuclear vanadium complexes showed no difference to give the coupling product in high yields but with a different enantioselective manner; chiral mononuclear vanadium(V) complexes showed better enantioselectivites than that of the dinuclear vanadium(V) complexes. A competing heterocoupling study and a linear correlation between the ee of the mononucaler vanadium catalyst and ee of the heterocoupling suggested that the heterocoupling involves an intermolecular radical-anion coupling pathway. In this Account, we summarize the recent advances in vanadium-catalyzed coupling reactions that produced important chiral molecules, such as biresorcinols, polycyclic biphenols, oxa[9]helicenes, bihydroxycarbazoles, and C 1-symmetrical biarenols, and their coupling reaction mechanisms. By pursuing vanadium catalysis, we believe numerous additional transform...

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Chemo- and enantioselective hetero-coupling of hydroxycarbazoles catalyzed by a chiral vanadium(v) complex

Abstract: The catalytic enantioselective oxidative hetero-coupling of arenols using a chiral vanadium(v) complex has been developed. The coupling of hydroxycarbazole derivatives with various arenols provided axially chiral biarenols in high chemo-,...

Cited by 22 publications

References 75 publications

Chemo- and regioselective cross-dehydrogenative coupling reaction of 3-hydroxycarbazoles with arenols catalyzed by a mesoporous silica-supported oxovanadium

Chemo- and regioselective cross-dehydrogenative coupling reaction of 3-hydroxycarbazoles with arenols catalyzed by a mesoporous silica-supported oxovanadium

Catalytic Oxidative Coupling of Phenols and Related Compounds

Atroposelective Synthesis of C–C Axially Chiral Compounds via Mono- and Dinuclear Vanadium Catalysis

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