methyl (2Z,6Z)-3-methyl-6-(3-isopropylidene-1-cyclopentylidene)-2-hexenoate

methyl (2E,6Z)-3-methyl-6-(3-isopropylidene-1-cyclopentylidene)-2-hexenoate

(Z)-6-[2,2-Dimethyl-1-oxa-spiro[2.4]hept-(5Z)-ylidene]-3-methyl-hex-2-enoic acid methyl ester

methyl (2E,6Z)-6-<3',3'-dimethylspiro-3-ylidene>-3-methyl-2-hexenoate