Palladium-Catalyzed Coupling Reactions of Aryl Chlorides

Abstract

Collectively, palladium-catalyzed coupling reactions represent some of the most powerful and versatile tools available to synthetic organic chemists. Their widespread popularity stems in part from the fact that they are generally tolerant to a large number of functional groups, which allows them to be employed in a wide range of applications. However, for many years a major limitation of palladium-catalyzed coupling processes has been the poor reactivity of aryl chlorides, which from the standpoints of cost and availability are more attractive substrates than the corresponding bromides, iodides, and triflates. Traditional palladium/triarylphosphane catalysts are only effective for the coupling of certain activated aryl chlorides (for example, heteroaryl chlorides and substrates that bear electron-withdrawing groups), but not for aryl chlorides in general. Since 1998, major advances have been described by a number of research groups addressing this challenge; catalysts based on bulky, electron-rich phosphanes and carbenes have proved to be particularly mild and versatile. This review summarizes both the seminal early work and the exciting recent developments in the area of palladium-catalyzed couplings of aryl chlorides.

Highly Reactive, General and Long-Lived Catalysts for Palladium-Catalyzed Amination of Heteroaryl and Aryl Chlorides, Bromides, and Iodides: Scope and Structure–Activity Relationships

“…These factors have limited the use of the coupling of amines to produce less expensive intermediates and commodity building blocks. 6,7 (1) Three general classes of reagents react slowly and require high loading of catalyst, even with most of the most recently developed systems: 8 (1) primary alkylamines, [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] which form substantial amounts of product from diarylation in the absence of an ortho substituent on the haloarene reagent or an excess of the primary amines; (2) heteroaryl halides, 11,12,15,17,19,[24][25][26][27][28][29][30][31][32] which are important for medicinal chemistry applications, but have reacted more slowly, with narrower scope, and with higher catalyst loadings than aryl halides; and (3) aryl iodides, which react more slowly and provide lower yields than aryl bromides in couplings with amine nucleophiles, 15,17,[33][34][35][36][37][38][39][40][41][42]…”

A simple way of recycling of homogeneous catalyst in Suzuki reaction

“…Compounds 9d, 12a, and 12b were identified by mass using LCÁMS. NMR was recorded on a 400 MHz Bruker instrument using d 6 -DMSO as solvent. Chemical shifts (d) are expressed in parts per million (ppm) coupling constants (J) are in Hz.…”

“…Chemical shifts (d) are expressed in parts per million (ppm) coupling constants (J) are in Hz. The 1 H and 13 C NMR chemical shifts are reported relative to the resonance of the residual protons of the solvent was used as internal standard for 1 H (d02.50 DMSO-d 6 ) and all deuterium solvent signals for 13 C (d039.5 DMSO-d 6 ). All measurements were carried out at 298 K. Abbreviations used in the description of NMR data are as follows: br, broad; s, singlet; d, doublet; t, triplet; m, multiplet.…”

Theoretical studies of iridium-mediated tautomerization of substituted pyridines

“…The optimized structural data of complex 9 ( Fig. 2) were found to closely match those of the directly analogous methyl derivative (2), and in almost all cases, the calculated bonds are within 0.05 Å longer than the corresponding experimental ones, and this overestimation is typical for the B3LYP functional. Therefore these consistent data support the general reliability of our method and the proper selection of the basis sets.…”