Visible-light-promoted acridine red catalyzed aerobic oxidative decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones

Abstract

Visible-light-mediated procedure has been developed for the synthesis of 3-acyl quinoxalin-2(1H)-ones through acridine red catalyzed decarboxylative acylation of α-oxo-carboxylic acids with quinoxalin-2(1H)-ones.

Photoredox Catalyst Free, Visible Light‐Promoted C3−H Acylation of Quinoxalin‐2(1H)‐ones in Water

“…Noteworthy, the unprotected quinoxalinones did not work at all under the optimal reaction conditions in previous reported photoredox catalytic methods. [15] As the results shown in Table 1, the desired 3-acylated product 3 aa could be obtained in 66% yield when the reaction was performed in the presence of 2.0 equiv. phenyliodine(III) diacetate (PIDA) under irradiation with 24 w blue LED in acetone for 12 h at rt (entry 1).…”

“…Then, visible light-promoted IÀ O bond homolysis of A provides I-centered radical B along with an O-centered radical C. Fragmentation of B or C generates the key acyl radical, which can be confirmed by TEMPOtrapping experiment (see the SI). Addition of acyl radical to C=N bond of quinoxalin-2(1H)-one yields nitrogen-centered radical species D, which subsequently undergoes 1,2-H migration to give the carboncentered radical E. [5,15] Oxidative deprotonation of E affords the final 3-acyl quinoxalin-2(1H)-one products.…”

“…In 2020, Wei group discovered a visible light-promoted 3-acylation reactions of quinoxalin-2(1H)-ones by using molecule O 2 as the terminal oxidant (Scheme 1d). [15] However, 3,6bis(methylamino)-xantyliumchloride (Acridine Red) is required to act as photoredox catalyst to run the process. [16] It is still important to discover novel and efficient photocatalytic approaches to synthesize 3-acyl quinoxalin-2(1H)-one derivatives, especially under green and sustainable reaction conditions (e. g. photoredox catalyst free, H 2 O as the reaction media, room temperature).…”

“…Within the frame of our ongoing research interests in heterocycle synthesis [17] and visible light-promoted fine chemical transformations, [18] we describe herein a visible light-promoted environmentally-friendly approach to the synthesis of biologically important 3-acyl quinoxalin-2(1H)-ones (Scheme 1e). Comparing with the reported photocatalytic strategy, [15] photoredox catalyst is not required and the reaction is promoted by cheap and mild phenyliodine(III) diacetate (PIDA). [19] More significantly, water can be directly used as reaction solvent, and as we know one of the critical principles of green chemistry is the usage of safer solvent.…”

Recent Advances in Photocatalytic Functionalization of Quinoxalin‐2‐ones

“…In early 2020, the research group of Wei developed a protocol based on the Acridine Red ability for sensitizing triplet oxygen under the irradiation of Blue LEDs. [61] Using these optimal reaction conditions, they could synthesize a library of twenty eight differently substituted 3-acyl-quinoxalin-2-ones in moderate to good yields (Scheme 39). A series of aryl α-oxocarboxylic acids with electron-donating (Me or MeO) and electron-withdrawing (F, Cl, Br, and CF 3 ) groups attached to the phenyl ring, heterocyclic α-oxocarboxylic acids as well as aliphatic α-oxocarboxylic acids were all suitable for this transformation, affording the corresponding functionalized quinoxalinones with good yields.…”