Biomimetic totalsynthesis of citromycetin (1a) is described. Regioselective cyclization of the enetrione (5), chosen as a common intermediate for the syntheses of citromycetin (1a) and fulvic acid (2a), with conc. HCI–AcOH (1:30) gave the chioromethylpyrone (7b). Oxidation, followed by demethylation of the substituents of the pyranobenzopyranone obtained by debenzylation and cyclization of the reactive