Ferric chloride-catalyzed synthesis of indoles using the intramolecular amination of aryl bromides

Synthesis of Indoles via Electron-Catalyzed Intramolecular C–N Bond Formation

“…Finally, cyclization of substrates containing the base-sensitive acetyl group allowed us to obtain 1e, though in a modest yield. Using our new protocol, N-arylindoles 1a,f,h,o were afforded in better or comparable yields to those reported using the same substrates under Cu-, 14 Fe-, 15 and Pdcatalyzed 16 conditions (Scheme 1). Unfortunately, when these conditions were applied to 2 derived from alkylamines, N-alkylindoles were formed in low yields with most of the starting materials being recovered.…”

“…Previously, we disclosed an efficient strategy toward N-functionalized 1 H -indole-3-carboxylates 1 via a Cu- or Fe-catalyzed intramolecular cyclization of 3-amino-2-(2-bromophenyl)­acrylates 2 (Figure A). Compound 2 is easily accessed from (2-bromophenyl)­acetate, methyl formate, and primary amine (Figure B) .…”

“…Finally, cyclization of substrates containing the base-sensitive acetyl group allowed us to obtain 1e , though in a modest yield. Using our new protocol, N -arylindoles 1a , f , h , o were afforded in better or comparable yields to those reported using the same substrates under Cu-, Fe-, and Pd-catalyzed conditions (Scheme ).…”

“… a Performed on a 0.1 mmol scale as a semione-pot procedure. b Yields are isolated yields calculated over two steps from 3 . c Yields under Cu, Fe, and Pd catalysis were taken for comparison from refs, , and , respectively. d See the SI for details. e Compound 2y was obtained following ref . …”

Synthesis of N‐Substituted Condensed Tetrahydropyridine‐Based Enaminones via Palladium‐Catalyzed Intramolecular C–N Cross‐coupling

“…Within them, the C–N cross‐coupling variant (Buchwald–Hartwig reaction) is probably the most widespread carbon‐heteroatom bond‐forming reaction, and protocols allowing successful N ‐arylations of practically all imaginable substrates can be found in the literature . Compared with other substrates, enaminones and related compounds are still rather neglected substrates from this point of view . Owing to the lowered nucleophilicity of their nitrogen atom, enaminones can be challenging substrates for this kind of transformation.…”