In the presence of aqueous solutions of alkali, 2-bromomethyl-3,9-dihydro-2H-furo[2,3-b]quinolin-4-one is subjected to dehydrobromination and converted to 2-methyl-9H-furo[2,3-b]quinolin-4-one which exists in acid solution in the 4-oxo-and in base in the 4-hydroxy tautomeric forms.