Application of Photochemical/Electrochemical Synthesis in C—H Functionalization of Quinoxalin-2(1H)-one

Abstract

Quinoxalin-2(1H)-ones are a kind of important nitrogen-containing heterocyclic compounds, which have strong biological activity and chemical properties, and play an important role in synthesis chemistry, functional materials, drugs and so on. In recent years, the construction of 3-functionalized quinoxalin-2(1H)-one by C-H functionalization has attracted the attention of many scholars and made important progress. Among them, green chemistry oriented photocatalysis and electrochemical synthesis are becoming powerful tools for C-H functionalization of quinoxaline-2(1H)-one. In view of the great influence of photochemistry in synthetic chemistry, the research status of C-H functionalization of quinoxaline-2(1H)-one in visible light catalysis and electrochemical synthesis is summarized, hoping to promote the further development of green synthesis strategy in the functionalization of nitrogen-containing heterocycles. Keywords quinoxalin-2(1H)-one; visible-light; electrochemistry; C-H functionalization 喹喔啉-2(1H)-酮作为一种重要的含氮杂环单元, 具 有很强的生物活性与优异的化学特性, 并背被泛应用于 合成化学、材料、天然产物和药物工业领域 [1] . 其中, 3-取代的喹喔啉酮-2(1H)-酮表现出独特特性和生物活性, 常被开发成潜在的强效药物, 如抗肿瘤药、 抗糖尿病药、 抗炎药、减肥药及心血管药等 [2] (图 1). 近年来, 喹喔啉-键、C-O 键、C-N 键、C-S 键、C-P 键等), 从而实 现喹喔啉-2(1H)-酮的烷基化、芳基化、酰基化、三氟甲 基化、烷氧基化、亚磺酰化、硅烷化、磷酸化和醚化等 (Scheme 1) [4] .

Recent Developments in Direct C–H Functionalization of Quinoxalin-2(1H)-Ones via Multi-Component Tandem Reactions

“…Furthermore, the quinoxalin-2(1 H )-one fragment is a promising electron-withdrawing substituent for the development of push-pull systems with promising photophysical properties for various applications in material science [ 13 , 14 ]. In particular, the C3-substituted quinoxalin-2(1 H )-one derivatives show a broad range of biological activities ( Scheme 2 ) [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. The direct C–H functionalization of quinoxalin-2(1 H )-ones at the C3 position is the most cost-effective way to synthesize a wide range of quinoxalin-2(1 H )-one derivatives containing valuable functional groups.…”

“…The direct C–H functionalization of quinoxalin-2(1 H )-ones at the C3 position is the most cost-effective way to synthesize a wide range of quinoxalin-2(1 H )-one derivatives containing valuable functional groups. In recent years, quinoxalin-2(1 H )-one has been prominently studied [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Furthermore, the direct acid-catalyzed C–H bond functionalization of quinoxalin-2(1 H )-one based on a nucleophilic aromatic substituted hydrogen approach (S N H -reaction) is of equal interest [ 25 , 26 , 27 , 28 , 29 ].…”

Selectfluor-Mediated Regioselective C-3 Alkoxylation, Amination, Sulfenylation, and Selenylation of Quinoxalin-2(1H)-ones

“…Due to the immense importance of quinoxalin-2­(1 H )-one in various fields, it is not surprising that constant efforts have been directed to develop sustainable and economical methods for synthesizing and functionalizing this heterocyclic framework . In this context, functionalization at the C3 position of quinoxaline-2­(1 H )-one via direct C–H bond activation/functionalization has emerged as a powerful strategy for constructing 3-substituted quinoxaline-2­(1 H )-ones . In recent years, considerable efforts have been made for the synthesis of 3-substituted quinoxaline-2­(1 H )-ones via direct C–H arylation, acylation, alkoxylation, amination, phosphorylation, and sulfenylation under transition metal-catalysis or photocatalysis.…”

Photoredox catalysis leading to triazolo-quinoxalinones at room temperature: selectivity of the rate determining step

“…A review on the recent literature of synthetic methodologies to access quinoxalinone derivatives, shows that the most widely used strategy is the introduction of substituents into the 3-position of quinoxalin-2(1 H )-one by C–H functionalization. The syntheses cover a broad scope of strategies, including microwave irradiation to generate the alkyl radical precursors for cross-dehydrogenative alkylation reaction, 26 photochemical/electrochemical catalysis, 27,28 the use of simple visible light to difunctionalize 2,3-dihydrofuran with quinoxalinones with a selective anti-addition, 29 the simple alkoxylation with low cost alcohols, 30 or even the use of blue LED irradiation for a regioselective decarboxylative alkylation of non-aromatic C–H bonds. 31 The arylation of quinoxalinones with aryldiazonium salts, 32 omitting any use of an oxidant or an additive, or the synthesis of ( E )-quinoxalinone oximes by a multicomponent reaction involving a radical coupling and the Mannich reaction 33 also promote very efficient derivatisation of quinoxalinones.…”