An Easily Modifiable/Traceless Directing Group Usable for Aromatic C-H Activation

An efficient reagent for introducing a directing group, 2-(diisopropylsilyl)pyridine (PyDipSiH), has been developed by Gevorgyan et al. and used for the regioselective aromatic C-H bond activation by introduction of the pyridyldiisopropylsilyl (PyDipSi) group into aromatic rings. The PyDipSi group is directly introduced into arenes by the treatment of PyDipSiH with aryllithium derivatives and the ortho-position of the C-H bond of the arene is activated by the coordination from a nitrogen atom on the pyridyl group. In a case of palladium catalyzed C-H bond activation, ortho-selective acyloxylation and halogenation proceed. Further transformations of the PyDipSi directing group to other functional groups such as iodide and boronate are achieved as well as removal of the directing group by AgF salt.