Palladium-Catalyzed Suzuki−Miyaura Coupling of Pyridyl-2-boronic Esters with Aryl Halides Using Highly Active and Air-Stable Phosphine Chloride and Oxide Ligands

Abstract

The palladium-catalyzed Suzuki-Miyaura coupling of pyridyl-2-boronic esters provided an efficient approach to useful biaryl building blocks containing a 2-pyridyl moiety. The convenient reaction protocol demonstrates its potentially wide applications in medicinal chemistry.

Direct ortho‐Arylation of N‐Phenacylpyridinium Bromide by Palladium‐Catalyzed CH‐Bond Activation

“…2,6-Di(4-methoxylphenyl)pyridine (7 d 4,156.3,137.3,132.3,128.2,117.1,114.0,pyridine (6 e 3,149.6,136.7,135.5,128.6 (d,J = 8.6 Hz),121.9,120.1,115.5 ppm (d,J = 21.5 Hz); MS (EI): m/z (%): 173 (100) [M] + , 172 (68.0); elemental analysis calcd (%) for C 11 H 8 FN: C 76.29,H 4.66,N 8.09;found: C 76.32;H 4.64;N 8.07. 2,pyridine (7 e): White solid; m.p.…”

“…[2] Although transition-metal-catalyzed cross-coupling reactions between organometallic electron-rich heterocycles and arylhalides have been widely used, their application has been limited to pyridine derivatives. [3,4] The reason for this is that the pyridine ring is electron deficient and the highly effective and relatively stable ortho-pyridyl organometallics have only been presented recently. [5] However, direct arylation of heterocycles has emerged as an alternative to the traditional crosscoupling reaction in past years [6] and pioneering work on the direct ortho-arylation of pyridine has made significant achievements.…”

Accurate Analysis of Boronic Pinacol Esters Using Low Residual Silanol Silica Based Reversed Phase HPLC

“…Although traditionally boronic acids were employed in this reaction, recent work has led to the finding that pinacol esters of boronic acids are often preferred due to the improved chemical stability. [11,12] These boronate esters can be hydrolyzed in situ to generate the boronic acid necessary for the cross-coupling reaction. [13][14][15][16][17] Furthermore, boronic acids may exist as mixtures of oligomeric anhydrides, especially the cyclic six-membered boroxines which further complicates their analysis.…”

Bulky N-acyl-pyridylbenzamidine Ligands for Palladium Catalyzed Suzuki–Miyaura Reaction

“…Meanwhile, catalysts containing different sorts of ligands have been intensively studied by numbers of researchers during the past two decades in this hot area [7][8][9]. These reported ligands were mainly focused on phosphines [10][11][12].…”