A highly efficient palladium acetate-catalyzed ligand-freeSuzukireaction of 2,3,5-trichloropyridine with arylboronic acids in aqueous phase was developed. High yields of 3,5-dichloro-2-arylpyridines, a simple Pd source, absence of ligands, and environmentally benign as well as mildreactionconditions are important features of this method.
Transition-Metal-Free Decarboxylative Arylation of 2-Picolinic Acids with Arenes under Air Conditions
作者:Xitao Zhang、Xiujuan Feng、Chuancheng Zhou、Xiaoqiang Yu、Yoshinori Yamamoto、Ming Bao
DOI:10.1021/acs.orglett.8b03043
日期:2018.11.16
transition-metal-free, and direct decarboxylative arylation of 2-picolinic acids with simple arenes is described. The oxidativedecarboxylative arylation of 2-picolinic acids with arenes proceeds readily via N-chloro carbene intermediates to afford 2-arylpyridines in satisfactory to good yields under transition-metal-free conditions. This new type of decarboxylative arylation is operationally simple
2,3- and 2,5-Dibromopyridines reacted with arylboronic acids, catalyzed by Pd(OAc)(2)/PPh3 in the presence of K2CO3 in CH3CN/MeOH (2:1) at 50 degrees C for 24 h, to afford 2-aiylpyridines in good to high yields, while 2,4-dibromopyridine reacted with arylboronic acid pinacol esters, catalyzed by Pd(OAc)(2)/PPh3 in the presence of KOH in CH3CN at 70 degrees C for 24 h, to afford 2-arylpyridines in good to high yields. To expand this methodology, a 170-HSD1 inhibitor was synthesized in good yield. (C) 2013 Elsevier Ltd. All rights reserved.
Halogenation of the 3-position of pyridines through Zincke imine intermediates
作者:Benjamin T. Boyle、Jeffrey N. Levy、Louis de Lescure、Robert S. Paton、Andrew McNally
DOI:10.1126/science.add8980
日期:2022.11.18
required for drug and agrochemical development. However, despite more than a century of synthetic endeavors, halogenation processes that selectively functionalize the carbon–hydrogen bond in the 3-position of a broad range of pyridine precursors remain largely elusive. We report a reaction sequence of pyridyl ring opening, halogenation, and ring closing whereby the acyclic Zincke imine intermediates