The Directed ortho-Lithiation of Aryl Tetramethylphosphorodiamidates

Aryl tetramethylphosphorodiamidates were effectively ortho-lithiated with sec-BuLi in tetrahydrofuran at −105 o C. The resulting lithiated species were trapped with a variety of electrophiles at −105 o C to provide ortho-substituted phosphorodiamidates. When the lithiation was carried out at −78 o C, O→C migration of the bis(dimethylamino) phosphoryl group took place rapidly and 2-hydroxyarylphosphonic tetramethyldiamides were produced regioselectively. The ortho-directing ability of the phosphorodiamidates was investigated by intermolecular competition experiments with other directed metalation groups