Facile synthesis of isatins by direct oxidation of indoles and 3-iodoindoles using NIS/IBX

Synthesis of Azacarbolines via PhIO2-Promoted Intramolecular Oxidative Cyclization of α-Indolylhydrazones

“… d Performed at 0 °C. e 1-Methyl-1 H -indole-2,3-dione 17 (12% yield) byproduct was also recovered. f Cu(OTf) 2 (5 mol %) was added.…”

Tunable Electrocatalytic Annulations of o-Arylalkynylanilines: Green and Switchable Syntheses of Skeletally Diverse Indoles

“…Consequently, the introduction of halogen into the indole ring has attracted widespread attention over the past few years. Generally, strategies for halogenation of indoles include traditional electrophilic halogenation of indoles with halogen (I 2 and Br 2 ) or NIS (Scheme a, path (i)) and electrophilic cyclization of o -arylalkynylanilines (Scheme a, path (ii)) . Despite these advances, some critical issues, particularly concerning environmental aspects, remain unsolved due to poisonous and corrosive reagents such as iodine and bromine being used in those methods .…”

Approaches for Transition Metal-Free Photocatalytic Oxidation Reactions

“…In 2019 Chandra et al showed the oxygenation utilizing NIS and IBX in DMSO. [102] Muneer et al showed photocatalyzed oxygenation in aqueous solution with titanium dioxide (Scheme 10). [103] In 2016 Jiang et al showed a versatile chemo selective methodology utilizing dicyanopyrazine-dervied chromophores for the formation of different isatins from indoles.…”

“…Scheme 10: Oxidations of indole to isatins and further functionalization. [102][103][104] Pyrroles and maleimides are also essential building blocks in nature and form an integral part of the synthesis of porphyrinogens like heme and chlorophyll. [105] In this case the oxygenation of pyrrole to maleimide is easy to achieve but includes other obstacles.…”

“…[95] Scheme 11: Selected named reactions for the synthesis of pyrroles. [98][99][100][101][102][103] The oxygenated form of pyrrole, the maleimide, is thereby a highly reactive reagent which has a multitude of different applications (Scheme 12). [113] It is used for thermoset polymer synthesis, [114] as preparation of SMCC reagents which is one of the most widely used bioconjugations in biotechnology.…”