Kauranes and Villanovanes

More than 200 kauranes are reported to exist in plants The parent hydrocarbon (-)-kaurane occurs Aristolochia triangularis, and its 16a-stereoisomer in various sediments. (+)-16,17-Dihydroxy-9(ll)-kauren-19-oic acid is one of the constituents 

Villanovanes are rare diterpenes. Some representatives were first isolated from Villanova titicaensis, exemplified by 3,13,17- and 13,17,19-villanovantriol, both as esters of isobutyric acid. (-l-)-Villanovan-13a,19-diol is found in Stemodia mari-tima. 

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