Acrostalidic acid

The route could start from the mixture of cis- and /rans-communic acids (or also from other diterpenes, such as isocupresic acid). The isolation of hydroxyacid I as a natural product from Acrostalagmus reinforces the possiblity of the existence of diene II as a key precursor, not only of isoacrostalidic acid and acrostalidic acid, but also of dilactone III. The straightforward chemical conversion of I into III in a recent publication by Barrero et al. [20] supports this hypothesis. 

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