Alkoxy and cyclic ether oxygens exhibit disparate capabilities for directing ortho lithiation

Article abstract of DOI:10.1016/S0040-4039(00)73670-7

Metalation of 4_a and 4_b with n-butyllithium under kinetically controlled conditions (C₅H₆, 20 °C or Et₂O, TMEDA (2 equiv), 20 °C) leads to preferred deprotonation α to the heterocyclic ring.