5,6-dimethyl-3-propoxycarbonyl-7-oxabicyclo[2.2.1]heptane-2-carboxylic acid;3-(5,6-dimethyl-3-propoxycarbonyl-7-thiabicyclo[2.2.1]heptan-2-yl)prop-2-ynoic acid;2-O-methyl 3-O-propyl 5,6-dimethyl-7-thiabicyclo[2.2.1]heptane-2,3-dicarboxylate;propyl 9,10-dimethyltetracyclo[6.2.1.13,6.02,7]dodecane-4-carboxylate;2-trimethylsilylethyl 9,10-dimethyl-11-oxatetracyclo[6.2.1.13,6.02,7]dodecane-4-carboxylate;2-trimethylsilylethyl 9,10-dimethyltetracyclo[6.2.1.13,6.02,7]dodecane-4-carboxylate;hydrate