2,3-Disubstituted indoles bearing 2-hydroxyphenyl moieties at their C3 positions were synthesized from readily available 2-chlorophenols and alkynylanilines via aminopalladation/reductive elimination using Pd–dihydroxyterphenylphosphine catalyst. The catalyst accelerates the introduction of the 2-hydroxyphenyl group at the C3 position of the indole.
Palladium-catalyzed cyclization of o-alkynyltrifluoroacetanilides followed by isocyanide insertion: synthesis of 2-substituted 1H-indole-3-carboxamides
A base-controlled synthesis of 2-substituted secondary and tertiary 1H-indole-3-carboxamides through PdCl2-catalyzed cyclization of o-alkynyltrifluoroacetanilides followed by isocyanide insertion has been developed. The reaction proceeds smoothly at ambient temperature using O2 in air as the sole oxidant of the palladium catalyst.
Palladium-Catalyzed Cyclization of <i>N</i>-Acyl-<i>o</i>-alkynylanilines with Isocyanides Involving a 1,3-Acyl Migration: Rapid Access to Functionalized 2-Aminoquinolines
the synthesis of functionalized 2-aminoquinolines via palladium-catalyzed annulation of N-acyl-o-alkynylanilines with isocyanides has been developed with high atom economy, in which an unconventional 6-endo-dig cyclization process is observed. Furtherinvestigations of the mechanism demonstrated that an intramolecular acyl migration of the N-protecting groups was involved in this transformation.
A novel palladium-catalyzed synthesis of free N−H 2,3-disubstituted indoles from arenediazonium tetrafluoroborates and 2-alkynyltrifluoroacetanilides is presented. The reaction tolerates a variety of useful substituents both in the starting alkyne and the arenediazonium salt, including bromo and chloro substituents, nitro, cyano, keto, ester, and ether groups, as well as ortho substituents such as