Furthermore, when both the iodoarene 1 and arene 2 are of electron-deficient character, synthesis of 3 via route B can be low-yielding due to insufficient oxidation of iodoarene 1 in the presence of BF3•OEt2 and inadequate nucleophilicity of arylboronic acid 4. In both routes, the use of acid sensitive 2 or 4 may cause problems.