Pyridylmethylamine–Palladium Catalytic Systems: A Selective Alternative in the C−H Arylation of Indole

Abstract

A highly efficient pyridylmethylamine‐Pd alternative catalytic system for the C−H arylation of indole was explored. Variously substituted aryl groups were regio‐ and chemoselectively installed at the indole nucleus by using barium hydroxide as the base. The method was found to be efficient even in the presence of hindered coupling partners and Pd‐reactive bonds.

Catalytic Au(i)/Au(iii) arylation with the hemilabile MeDalphos ligand: unusual selectivity for electron-rich iodoarenes and efficient application to indoles

“…25,26 The main challenge of the transformation is the control of regioselectivity in the absence of directing groups. Most transition metals tend to intrinsically favour C2 arylation,25,27 while direct arylations of indoles at the C3 position remain scant 28,29…”

“…No coupling product was detected either with N -acetyl indole. Indoles not depleted in electron density are needed for the reaction to take place, underpinning the electrophilic mechanism of the indole auration 28 c . Selective arylation of unprotected indoles is challenging.…”

Deciphering preferred geometries of pyridylmethylamines-based complexes: A robust strategy combining NMR, DFT and X-ray

“…11 Such compounds revealed especially valuable as catalytic systems in various synthetic organo-and metallo-promoted transformations including oxidative C-C bond formation, cycloaddition reactions, Friedel-Crafts alkylation, Henry reaction, Suzuki coupling, C-H arylation. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Figure 1. Pma modulation sites, transition metal and proton complexes and Zn II and Co II complexes.…”

Development of Pd Supported Catalysts Using Thiol‐Functionalized Mesoporous Silica Frameworks: Application to the Chemo‐ and Regioselective C‐3 Arylation of Free‐Indole

“…To reach this goal, active molecular catalytic systems were therefore developed [4–12] to address the challenging chemo‐ and regio‐selective arylation of indoles at the C ‐3 position. The few reported systems, based on palladium or iridium metals, that were able to achieve this reaction with high selectivity toward the C ‐3 arylated product, exhibited moderate TONs of ca 80 at maximum [13–19] . One exception is the catalytic system based on Pd(OAc) 2 and lithium bis(trimethylsilyl)amide that our group recently reported and that was able to achieve this targeted reaction with a TON of 1800 and very high yield in C ‐3 product (90 %) [20] .…”

“…The few reported systems, based on palladium or iridium metals, that were able to achieve this reaction with high selectivity toward the C-3 arylated product, exhibited moderate TONs of ca 80 at maximum. [13][14][15][16][17][18][19] One exception is the catalytic system based on Pd(OAc) 2 and lithium bis(trimethylsilyl)amide that our group recently reported and that was able to achieve this targeted reaction with a TON of 1800 and very high yield in C-3 product (90 %). [20] This reaction was also studied using transition metal free systems.…”