Bromine-lithium exchange of the mono-and dibromophenothiazines 1 and 3a regiospecifically furnishes upon electrophilic trapping with iodine the iodo-and diiodophenothiazines 2, 3b, and 3d in excellent yield. The 3-bromo-7-iodophenothiazine 3d can be submitted to regioselective and sequential Suzuki coupling reactions with phenothiazine mono-and bisboronates 4 and 5 and/or (hetero) aryl boronic acids to give ...