Direct C3-Selective Arylation of N-Unsubstituted Indoles with Aryl Chlorides, Triflates, and Nonaflates Using a Palladium–Dihydroxyterphenylphosphine Catalyst
successfully applied to the direct C3-arylation of N-unsubstituted indoles with arylchlorides, triflates, and nonaflates. This catalyst showed C3-selectivity, whereas catalysts with other structurally related ligands exhibited N1-selectivity. Complex formation between the lithium salts of the ligand and the indole is assumed to accelerate the arylation at the C3 position. Reactions using 3-alkylindoles afforded
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