From Reactive Oxygen Species to Reactive Brominating Species: Fenton Chemistry for Oxidative Bromination

Abstract

Fenton chemistry (FeII + H2O2 → HO•/HOO• + H2O) generates reactive oxygen species (ROS) that are used for treatment of wastewater and oxidation of organic molecules and play a key role in biological oxidation systems. This study shows that Fenton chemistry can be used for generation of reactive brominating species (RBS) under neutral conditions at room temperature. The in situ RBS are successfully used for three types of oxidative bromination reactions. This green and nonacidic new method addresses the safety and environmental challenges of existing oxidative bromination methods. Additionally, this neutral Fenton–bromide system addresses the long-lasting problem of many functional haloperoxidase mimics that required strong acids for oxidation of bromide ion with hydrogen peroxide. This new green and mild method for generating RBS will significantly benefit the wide applications of brominated organic compounds in organic synthesis and the fine chemical and pharmaceutical industries.

Nanosecond‐pulsed microbubble plasma reactor for plasma‐activated water generation and bacterial inactivation

“…In addition, under acidification produced by NO 3 − , NO 2 − can produce NO through deprotonation reaction under acidic conditions, which has strong toxicity to cells. [ 14,67 ]…”

“…In addition, under acidification produced by NO 3 − , NO 2 − can produce NO through deprotonation reaction under acidic conditions, which has strong toxicity to cells. [14,67] 3.6. 13) and ( 14) in Table 1, Therefore, H 2 O 2 plays an active role in prolonging the activity of PAW, especially at low temperatures.…”

Bromide Oxidation: A Safe Strategy for Electrophilic Brominations

“…[48] Fe 2 + /3 + or Ce 3 + /4 + can also catalyse the oxidation of bromides in a Fenton-like pathway. [49] Hydrogen peroxide has been successfully used to oxidatively brominate (di)ketones, [44,50] arenes, both through electrophilic ring bromination [35-39,41b,45,48-,50d,51] and radical side-chain bromination, [36,52] heteroarenes, [40,51b] and unsaturated bonds. [28a,46,49-,50d,53] One of the advantages of hydrogen peroxide is its strong oxidation potential, but this is also a major downside: it can react with functional groups on the substrate and cause oxidation rather than bromination.…”

Palladium-Catalyzed One-Pot Synthesis of Pyrroloindolines from 2-Alkynyl Arylazides and Thioacetamides

“…The pyrroloindoline core skeleton can be found in a variety of natural products and has been receiving much attention due to its exhibition of biological and pharmaceutical activities, such as antibacterial, anticancer, and anticholinesterase (Figure ). In view of the drug activities and medicinal value of pyrroloindolines, a number of elegant strategies have been developed for their synthesis. − Among those established reactions, the intermolecular dearomative cycloaddition of indoles with 2-amidoacrylates, − 4-aryl-1-sulfonyl-1,2,3-triazoles, aziridines, − or α-halohydroxamates − was a general method (Scheme a). In addition, the intramolecular dearomatization annulation of tryptamines to pyrroloindolines was also explored extensively (Scheme b).…”

“… In view of the drug activities and medicinal value of pyrroloindolines, a number of elegant strategies have been developed for their synthesis. − Among those established reactions, the intermolecular dearomative cycloaddition of indoles with 2-amidoacrylates, − 4-aryl-1-sulfonyl-1,2,3-triazoles, aziridines, − or α-halohydroxamates − was a general method (Scheme a). In addition, the intramolecular dearomatization annulation of tryptamines to pyrroloindolines was also explored extensively (Scheme b). Other synthetic methods such as cyclization of 3-substituted indolin-2-ones and fischer indole synthesis were also efficient synthetic routes to pyrroloindolines (Scheme c,d).…”