Two exceptional lithiations in the chromone series
Abstract
With lithium di-isopropylamide in tetrahydrofuran at –70 °C followed by pivaloyl chloride the 2-pivaloylmethyl-3-methoxymethylchromone (1) affords by a novel aromatic substitution the 8-pivaloylchromone (3); lithiation of the 2-(2-furyl)chromone (7) with one mol. Equiv. of the reagent followed by carbonation leads not to monocarboxylic acids but to a 50% yield of the dicarboxylic acid (8).