Facile Synthesis of Functionalized Oligophenothiazines via One-Pot Bromine-Lithium Exchange-Borylation-Suzuki Coupling (BLEBS)

The bromine-lithium exchange in bromophenothiazines followed by transmetalation with trimethyl borate and addition of palladium catalyst, 1.2 equivalents of a base, and an aryl halide yields the cross-coupling products in moderate to very good yields.