Mechanism of aromatic lithiation reactions—Importance of steric factors

N,N-Dimethyl-1-naphthyIamine and N,N-dimethyl-2-aminobiphenyl do not undergoortho-lithiation although lithiation at a distant, but sterically close, position does occur. The result, although apparently anomalous, can be explained by Roberts-Curtin mechanism, taking into consideration the steric strain present at the transition state corresponding to the proton abstraction process.