arylmagnesium halides (phenylmagnesium chloride, mesitylmagnesium bromide, 4-(methoxycarbonyl)phenylmagnesium chloride and 4-cyanophenylmagnesium chloride) and halopyridines allowed the synthesis of substituted pyridines. Owing to the remarkably mild conditions used (often below 0°C), the reaction could be extended to the use of functionalized halopyridines, haloquinolines and halodiazines.
Difunctionalized pyridines can be prepared by a Pd(0)-catalyzedcross-coupling of functionalized arylmagnesium compounds with chloro- or bromopyridines at temperatures as low as −40°C. An addition–elimination mechanism involving a palladate intermediate is proposed.