3-hydroxy-Δ6,7-8,9-O-isopropylidene-1-oxa-spiro[4.5]decan-2-one

8,9-dihydroxy-1-oxa-spiro[4.5]dec-6-en-2-one

(1R,2S,4R,5R,6R)-4,5-dihydroxydihydro-5'H-7-oxaspiro[bicyclo[4.1.0]heptane-2,2'-furan]-5'-one

3-(tert-butyl-diphenyl-silanyloxy)-8,9-dihydroxy-1-oxa-spiro[4.5]dec-6-en-2-one

(3aR,5R,7aS)-4'-((tert-butyldiphenylsilyl)oxy)-2,2-dimethyl-3a,3',4',7a-tetrahydro-4H,5'H-spiro[benzo[d][1,3]dioxole-5,2'-furan]-5'-one