3,5-dihydroxy-1,8-dimethoxy-4-(methoxycarbonyl)-9H-xanthen-9-one

1,8-dimethoxy-5-(t-butyldimethylsilyloxy)-3-hydroxy-4-methoxycarbonyl-9H-xanthen-9-one

1,8-dimethoxy-5-(t-butyldimethylsilyloxy)-4-methoxycarbonyl-3-methoxymethyl-9H-xanthen-9-one

1,8-dimethoxy-5-(t-butyldimethylsilyloxy)-4-formyl-3-methoxymethyl-9H-xanthene-D9,δ-butane

5-(t-butyldimethylsilyloxy)-1,8-dimethoxy-4-(ethyl-3'-formylpropanoate)-3-O-methoxymethyl-9H-xanthen-Δ9,δ-butane