Lithiation of Aromatic Rings

Another effect of coordination is facilitated lithiation with -BuLi. Lithiation at the ortho position takes place with anisole, chlorobenzene and fluorobenzene 223, and reaction of the lithiation products 224 with electrophiles gives the ortho product 225 after decomplexation [58], This selective lithiation was applied to the synthesis of the 

---

Typically, superbases care little for coordination effects, and simply remove the most acidic proton on offer this provides useful alternative selectivities in the lithiation of aromatic rings, for example. With groups that direct principally by acidification, orthomet-allation occurs, and treatment with BuLi—KOBu-f is the most efficient way of orthofunc-tionalizing fluorobenzene or trifluoromethylbenzene (Scheme 241). ... 

---