Our interest in the synthesis of 3-methyl-lH, lOH-pyrano [4, 3-b][llbenzopyran-10-one ring system was stimulated by the fact that 7, 8-dihydroxy-3-methyl-l0-oxo-lH, 10H-pyrano [4, 3- b][11 benzopyran-9-carboxylic acid (anhydrofulvic acid) is the key intermediate in the synthesis of the fungal metabolite fulvic acid.'Our method gives a compound that has the critical fused features of fulvic acid. There now remains the substantial task of constructing ...
