(S)-4',9,9'-Trioxo-5',7'-dimethoxy-8',10-dihydroxy-4,4',9,9'-tetrahydrospiro[benzo[1,2-b:5,4-c']dipyran-2(3H),2'(3'H)-naphtho[2,3-b]furan]-7-carboxylic acid methyl ester

(S)-4,4',9,9'-Tetrahydro-8',10-dihydroxy-5',7'-dimethoxy-4',9,9'-trioxospiro[benzo[1,2-b:5,4-c']dipyran-2(3H),2'(3'H)-naphtho[2,3-b]furan]-7-carboxylic acid methyl ester

(2S)-4,4',9,9'-Tetrahydro-8',10-dihydroxy-5',7'-dimethoxy-4',9,9'-trioxospiro[benzo[1,2-b:5,4-c']dipyran-2(3H),2'(3'H)-naphtho[2,3-b]furan]-7-carboxylic acid methyl ester