Toward a Better Understanding on the Mechanism of Ortholithiation. Tuning of Selectivities in the Metalation of <i>meta</i>-Anisic Acid by an Appropriate Choice of Base
[GRAPHICS]If employed in THF at 0 degrees C, LTMP metalates meta-anisic acid at the doubly activated position. In contrast, n-BuLi/t-BuOK deprotonates position C-4 preferentially at low temperature. Functionalization at C-6 requires protection of the C-2 site beforehand. As a result of these findings, a new mechanism is proposed for the heteroatom-directed ortholithiation of aromatic compounds.
CABIDDU S.; MELIS S.; PIRAS P. P.; SOTGIU F., J. ORGANOMETAL. CHEM., 1979, 182, NO 2, 155-163