Improved synthesis of bis(chloromethyl)arene monomers

Abstract

We report here on the experimental conditions for radical chlorination that provide improved yields of 2,5-bis(chloromethyl) pyridine and pyrazine, as well as on theoretical calculations which were performed in order to gain some insight regarding the factors that affect reactivity in these systems. The difficulties encountered previously in the methyl functionalization of N-heteroarenes are not due to radical selectivity that produces low yield of the dichlorides or to lower reactivity of this type of compounds, but to the post-halogenation reactions that occur on the desired products. Therefore, a careful handling during and after the reaction allowed us to find conditions for product optimization of α, α′-dichlorinated monomers.