(3R,3aS,6aR)-3-(hydroxymethyl)-6a-(phenylthio)-3,3a,6,6a-tetrahydro-1H-cyclopenta[c]furan-1-one

tert-butyl (3S)-3-[(2S)-1,4-dioxaspiro[4.5]dec-2-yl]pent-4-enoate

tert-butyl (2R)-2-[(2S)-1,4-dioxaspiro[4.5]dec-2-yl]cyclopent-3-ene-1-carboxylate

tert-butyl (3R)-2-allyl-3-[(2S)-1,4-dioxaspiro[4.5]dec-2-yl]pent-4-enoate

tert-butyl (1R,2S)-2-[(2S)-1,4-dioxaspiro[4.5]dec-2-yl]-1-(phenylthio)cyclopent-3-ene-1-carboxylate