Terpenoid dicarboxylic acids

The defined geometry of these steps has permitted the synthesis of some cycloheptane acids related to terpenoid natural products. The key reaction was the rearrangement of a suitably substituted bicy-clo[4.2.0]octane. Thus the photoaddition of ethylene to 3-methylcyclohexenone gave the ketone (42), which was converted to the alcohol (43). On treatment with HgO and HBF4 this gave the unstable hydroxy aldehyde (44), which was readily oxidized to the dicarboxylic acid (45 Scheme 17).- Ring expansion methodology was also used in an approach to the synthesis of the trichothecenes (see Scheme 18).32... 

Chuman, T, H. Kaneko, and M. Noguchi Structure of a new terpenoid acid, l-Xi-methyl-3-Xi-isopropylcyclo-pentane-l-Xi, 2-Xi-dicarboxylic acid Agr. Biol. Chem. 

Lacfols via lactones, and diols from dicarboxylic acid anhydrides Labeled terpenoids... 

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