Modular Counter-Fischer–Indole Synthesis through Radical-Enolate Coupling

Synthesis of Indoles via Domino Reactions of 2-Methoxytoluene and Nitriles

“… , Consequently, numerous synthetic methods have been developed to access the 2-arylindole substructure. Classic routes include the Fischer indole synthesis while contemporary approaches employ transition-metal catalysts, including direct C-2 arylation of pre-existing indoles, − and intramolecular cyclization of functionalized anilines, − and many others. − Some of these approaches employ harsh reagents, highly functionalized precursors, or cryogenic temperatures that are challenging to access on scale. Therefore, more straightforward, efficient, and practical synthetic methods without addition of transition metals for the assembly of 2-arylindoles remain in demand.…”

Palladium‐Catalyzed Direct C−H Olefination of Polyfluoroarenes with Alkenyl Tosylates

“…2‐(2 , 4‐Dimethoxyphenyl)‐1 H ‐indole [41] . An oven dried 250‐mL single‐necked round bottomed flask equipped with a Teflon‐coated magnetic stir bar was charged with 2′,4′‐dimethoxyacetophenone (9.0 g, 50 mmol) and phenylhydrazine (6.5 mL, 55 mmol).…”

“…2-(2,4-Dimethoxyphenyl)-1H-indole. [41] An oven dried 250-mL single-necked round bottomed flask equipped with a Teflon-coated magnetic stir bar was charged with 2',4'-dimethoxyacetophenone (9.0 g, 50 mmol) and phenylhydrazine (6.5 mL, 55 mmol). Phosphoric acid (10 mL) was added slowly and the reaction mixture was stirred for 30 min.…”

KOtBu-Promoted Halogen-Bond-Assisted Intramolecular C–S Cross-Coupling of o-Iodothioanilides for the Synthesis of 2-Substituted Benzothiazoles

“…Later, the same group synthesized indoles via KO t Bu-promoted cyclization of imines with aryl halides . Very recently, Cheong and Lee developed a single-electron-transfer-mediated indole formation from 2-iodoaniline derivatives and ketones …”

“…5 Very recently, Cheong and Lee developed a single-electron-transfermediated indole formation from 2-iodoaniline derivatives and ketones. 6 Halogen bonds (XB) are a significant class of directional noncovalent interactions, which have gained prominence over the past few years. 7 Halogens, which are generally considered as sites of high electron density, adopt a Lewis acidic role on being covalently bound and, thus, interact with an electron-rich region of a neighboring atom or molecule (Lewis base).…”