Direct <i>ortho</i>-Arylation of Pyridinecarboxylic Acids: Overcoming the Deactivating Effect of sp<sup>2</sup>-Nitrogen
作者:Adam J. S. Johnston、Kenneth B. Ling、David Sale、Nathalie Lebrasseur、Igor Larrosa
DOI:10.1021/acs.orglett.6b03085
日期:2016.12.2
Direct arylations of pyridines are challenging transformations due to the high Lewis basicity of the sp2-nitrogen. The use of carboxylates as directinggroups is reported, facilitating the Pd-catalyzed C–H arylation of this difficult class of substrates. This methodology allows regioselective C3/C4 arylation, without the need to use solvent quantities of the pyridine, and using low-cost chloro- and