Synthesis of 5-methylfuro[3,2-b]pyridine-2-carboxylic acid

Oxidation of 3-hydroxy-6-methyl-2-hydroxymethylpyridine with manganese dioxide yielded the corresponding aldehyde, the condensation of which with diethyl bromomalonate furnished hydroxydihydrofuro3,2-b]pyridinediearboxylie acid ester. Saponification of the diester with concentrated hydrochloric acid afforded the hydrochloride of 5-methylfuro3,2-b]pyrjdine car-boxylic acid.