Meta-Dimethylation of Arenes via Catellani Reaction from Aryl Thianthrenium Salts.

Here we report the reaction of aryl thianthrenium salts that allows selective functionalization of the meta position of arenes. The combination of a site-selective thianthrenation with a Catellani reaction provides access to 3,5-dimethylated arenes. The developed reaction is complementary to the previously discovered reductive ipso-alkylation of aryl thianthrenium salts and extends the possibilities for late-stage methylation of arenes with a single aryl thianthrenium salt.