In Situ Preparation of Palladium Nanoparticles for C‐2 Selective Arylation of Indoles in Agro‐Waste Extract Based Mixed Solvents

Abstract

An efficient and practical method for the in situ generation of palladium nanoparticles was successfully established in a water extract of pomelo peel ash. The produced palladium nanoparticles were characterized by energy‐dispersive X‐ray spectroscopy elemental mapping, field emission scanning electron microscopy, high‐resolution transmission electron microscope, X‐ray powder diffraction, and showed high catalytic activity for selective C‐2 arylation of indoles. A series of 2‐arylindoles were smoothly installed in moderate to good yields through the direct palladium‐catalyzed cross‐coupling reactions of indoles and iodoarenes without external ligand, base, oxidant, and preinstallation directing group.

Recent advances in catalytic decarboxylative transformations of carboxylic acid groups attached to a non-aromatic sp2or sp carbon

“…99 Very recently, Jin et al described an elegant method for the synthesis of C-4-acylated coumarins 252 from α-keto acids and 3-nitrocoumarin 250 in a redox-neutral fashion. 100 Importantly, the reaction proceeds in the presence of 2,4,5,6tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN, 251) as the organophotocatalyst under metal free conditions. Control experiments suggest that the nitro radical generated upon the C-N bond cleavage of 3-nitrocoumarin serves as an electron acceptor to finish the photocatalytic cycle under external oxidant free conditions (Scheme 88).…”