Visible-light-induced C(sp³)–H activation for a C–C bond forming reaction of 3,4-dihydroquinoxalin-2(1H)-one with nucleophiles using oxygen with a photoredox catalyst or under catalyst-free conditions

Abstract

A convenient photocatalyzed oxidative coupling reaction of 4-alkyl-3,4-dihydroquinoxalin-2(1H)-one and its derivatives with a variety of nucleophiles was developed with a ruthenium photoredox catalyst and oxygen under a household compact fluorescent light. With a slower reaction rate, the cross coupling transformation can be achieved in the absence of an external photocatalyst with a similar isolated yield.An application to the synthesis of natural product cephalandole A was also demonstrated.

Recent Advances in Photocatalytic Functionalization of Quinoxalin‐2‐ones

“…Two years later, Hong and collaborators developed a protocol in which 4-alkyl-3,4-dihydroquinoxalin-2-ones were twoelectron oxidized to iminium cation. [84] This highly reactive intermediate was efficiently trapped by a large number of carbon nucleophiles, that can be classified in electron-rich arenes (Friedel-Craft reaction), silyl enol ethers (Mukaiyama-Mannich reaction) and TMSCN (Strecker reaction). They realized that the reaction could proceed without the need of a photocatalyst, albeit with lower performance than with Ru(bpy) 3 Cl 2 .…”

Recent Developments in Photo‐Catalyzed/Promoted Synthesis of Indoles and Their Functionalization: Reactions and Mechanisms

“…developed a visible light induced C−C bond formation reaction of 4‐alkyl‐3,4‐dihydroquinoxalin‐2(1 H )‐ones and indoles using household compact fluorescent lamps as the light source (Scheme 66). [103] As for the reaction mechanism, 4‐alkyl‐3,4‐dihydroquinoxalin‐2(1 H )‐one is firstly activated to radical cation intermediate 185 by Ru photocatalyst. The photocatalyzed transformation can also be performed in the presence of O 2 .…”

Recent Advances in Rapid Synthesis of Non-proteinogenic Amino Acids from Proteinogenic Amino Acids Derivatives via Direct Photo-Mediated C–H Functionalization

“…In 2011, Inoue's group has developed a protocol for the direct photo-cyanation of proline with TsCN under the irradiation of a 100 W medium pressure mercury lamp in high efficiency and diastereoselectivity (Scheme 38a) [83]. Additionally, TMSCN was used as an alternative cyanation reagent to provide the cyanated glycine derivative under the visible-light catalysis in 2018 (Scheme 38b) [84].…”

“…In 2011, Inoue's group has developed a protocol for the direct photo-cyanation of proline with TsCN under the irradiation of a 100 W medium pressure mercury lamp in high efficiency and diastereoselectivity (Scheme 38a) [83]. Additionally, TMSCN was used as an alternative cyanation reagent to provide the cyanated glycine derivative under the visible-light catalysis in 2018 (Scheme 38b) [84]. Particularly in 2018, Kanai and Oisaki's group reported a C(sp 3 )-H cyanation of methionine and its dipeptide through the cooperative visible-light photoredox/phosphate acid catalysis (Scheme 39) [85].…”

“…C(sp 3 )-H arylation of Gly derivatives with indoles through the cooperative catalysis of photoredox and cobalt.Aryl nucleophiles have been further expended to 7-azaindole, 1H-benzo[g]indole, pyrrole, naphthalen-2-ol, and phenol by Hong's group in the photoredox-mediated arylation reactions of glycine derivatives catalyzed by ruthenium complex with a household compact fluorescent light (CFL) (Scheme 42)[84]. Notably, this reaction could also occur under a catalyst-free condition with a significantly longer reaction time.…”