Photocatalytic aerobic oxidation/semipinacol rearrangement sequence: a concise route to the core of pseudoindoxyl alkaloids

Ding, Wei; Zhou, Quan‐Quan; Xuan, Jun; Li, Tianren; Lu, Liang‐Qiu; Xiao, Wen‐Jing

doi:10.1016/j.tetlet.2014.06.102

Cited by 102 publications

(43 citation statements)

References 58 publications

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“…With respect to the reaction mechanism, the Xiao group has contributed an elegant and systematic work to reveal a plausible single‐electron transfer process triggered from the reductive quenching of visible light‐excited photoredox catalyst with indoles . Our investigations using Stern–Volmer experiments also demonstrated the viability of DPZ as a photoredox catalyst to oxidize such indoles via single‐electron transfer .…”

Section: Methodsmentioning

confidence: 87%

“…Almost at the same time, Xiao and Lu and co‐workers reported cascade photooxidation and semipinacol rearrangement (i.e. 1,2‐shift) directly from 2‐aryl‐3‐alkyl‐substituted indoles by using Ru(byp) 3 Cl 2 as the photoredox catalyst (Scheme B) . Meanwhile, they attempted an enantioselective manifold, and presented a representative chiral product with 60 % ee by using an extra BINOL‐derived chiral phosphoric acid (CPA) catalyst.…”

Section: Methodsmentioning

confidence: 99%

“…It was found that the conversion was 65 % and the ratio of 2 a : 3 a was determined as 3:2, in which the ee values of 2 a and 3 a were 81 % and 59 % respectively. The enantioenriched 3 a indicated that the chiral CPA has furnished a stereocontrol to the O−O cleavage process after aerobic oxidation.…”

Section: Methodsmentioning

confidence: 99%

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Organocatalytic Asymmetric Cascade Aerobic Oxidation and Semipinacol Rearrangement Reaction: A Visible Light‐Induced Approach to Access Chiral 2,2‐Disubstituted Indolin‐3‐ones

Yin

et al. 2018

Chemistry An Asian Journal

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An enantioselective cascade aerobic oxidation and semipinacol rearrangement reaction of 2-aryl-3-alkyl-substituted indoles via visible-light-driven cooperative organophotoredox and H-bonding catalysis is reported. The current method provides an expedient and sustainable approach to furnish a variety of valuable chiral 2-aryl-2-alkyl-substituted indolin-3-ones in 64-90 % yield with 58-94 % ee. Preliminary control experiments present important insights into the stereochemistry.

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Section: Methodsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 99%

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Organocatalytic Asymmetric Cascade Aerobic Oxidation and Semipinacol Rearrangement Reaction: A Visible Light‐Induced Approach to Access Chiral 2,2‐Disubstituted Indolin‐3‐ones

Yin

et al. 2018

Chemistry An Asian Journal

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“…[87] Then, H 2 is produced by the reactiono f the Co III ÀHs pecies with H + to regenerate [Co III (dmgH) 2 pyCl]. [88,89] DPZC À reduces O 2 to O 2 C À ,w hich oxidizes the indole radicalc ation (I)t of orm iminium (II). [87] Zhang et al reported an expedient and efficient photocatalytic oxygenationo fi ndoles catalyzed by a dicyanopyrazine-derived chromophore (DPZ) to produce either isatins or formylformanilidesi ng ood yields (Scheme 12).…”

Section: Photocatalytic Hydroxylation Of Substrates With Organophotocmentioning

confidence: 99%

Photocatalytic Oxygenation Reactions Using Water and Dioxygen

2019

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Water (H2O) is the most environmentally benign reductant and is oxidized to evolve dioxygen (O2)—the greenest oxidant—in photosystem II. This Minireview focuses on photocatalytic oxygenation of substrates with H2O as an oxygen source and O2 as an oxidant. Metal complexes can be oxidized by two molecules of one‐electron oxidants with H2O to produce high‐valent metal–oxo complexes, which act as active oxidants for oxygenating organic substrates. When an appropriate oxidant is employed for the substrate oxidation, the reduced oxidant can be oxidized by dioxygen to regenerate the oxidant when water and dioxygen are used as an oxygen source and an oxidant, respectively. Photoinduced electron transfer from a substrate (S) to the excited state of complex [(L)MIII]+ produces a substrate radical cation (S.+), accompanied by the regeneration of [(L)MII]. S.+ then reacts with H2O to produce an OH adduct radical that is oxidized by [(L)MIII]+ to yield an oxygenated product (SO), in which the oxygen atom originates from H2O, accompanied by regeneration of [(L)MII]. Photocatalytic oxidation of H2O by O2 to produce H2O2 is combined with the catalytic oxygenation of substrates with H2O2 to produce the oxygenated products, in which the oxygen atom originates from O2 at the beginning but later from water. This Minireview provides a promising strategy for oxygenation of substrates by using H2O as an oxygen source and O2 as the greenest oxidant.

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“…[99] Durch photochemische Oxidation mit Tetrachlorkohlenstoff als stçchiometrischem Oxidationsmittel Unter Verwendung des Ruthenium-Katalysators 68 und einer chiralen Phosphorsäure wurde in der Gruppe von Xiao eine Sequenz aus photokatalysierter Oxidation und Semipinakol-Umlagerung enantioselektiv durchgeführt (ein Beispiel, 60 % ee). [104] …”

Section: Anionen Als Gegenionenunclassified

Enantioselektive Katalyse photochemischer Reaktionen

et al. 2015

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Die Natur des angeregten Zustands macht die Entwicklung chiraler Katalysatoren für enantioselektive photochemische Reaktionen zu einer enormen Herausforderung. Die Absorption eines 400‐nm‐Photons entspricht einer Energieaufnahme von etwa 300 kJ mol−1. Es bedarf innovativer Konzepte, um in einem derart großen Abstand vom Grundzustand Reaktionspfade zu eröffnen, die gezielt zu einem Enantiomer einer chiralen Verbindung führen. Hier werden die beiden wesentlichen Vorgehensweisen für homogen katalysierte, enantioselektive Prozesse diskutiert. Im ersten Teil werden chirale Photokatalysatoren besprochen, die in den photochemischen Schlüsselschritt eingreifen und in diesem Schritt eine asymmetrische Induktion bewirken. Im zweiten Teil werden Reaktionen vorgestellt, in denen die photochemische Anregung durch einen achiralen Katalysator erfolgt und die asymmetrische Induktion durch einen zweiten chiralen Katalysator gewährleistet wird (duale Katalyse).

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Photocatalytic aerobic oxidation/semipinacol rearrangement sequence: a concise route to the core of pseudoindoxyl alkaloids

Cited by 102 publications

References 58 publications

Organocatalytic Asymmetric Cascade Aerobic Oxidation and Semipinacol Rearrangement Reaction: A Visible Light‐Induced Approach to Access Chiral 2,2‐Disubstituted Indolin‐3‐ones

Organocatalytic Asymmetric Cascade Aerobic Oxidation and Semipinacol Rearrangement Reaction: A Visible Light‐Induced Approach to Access Chiral 2,2‐Disubstituted Indolin‐3‐ones

Photocatalytic Oxygenation Reactions Using Water and Dioxygen

Enantioselektive Katalyse photochemischer Reaktionen

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