MISCELLANEOUS DITERPENES

Cassane and Miscellaneous Tricyclic Diterpenoids.—A group of furanoid diterpenoids, related to the caesalpins, has been isolated from Pterodon emargina-and P. pubescens. They include compounds (39—42). Some further diterpene alkaloids of the cassaic acid class have been isolated from Erythro-phleum ivorense. 

Besides to the classes of taxanes discussed before, there are also some miscellaneous taxanes having a diversity of stmctural modifications in the tricyclic skeleton. Some examples include taxine A with a unique rearranged skeleton brevifoliol (natural diterpene isolated from Taxus baccata) and taxchinine A (acetoxybrevifohol) contain a five-membered A ring in place of the usual six-membered ring hydroxylated analogs of the taxanes which have an exocyclic double bond between C-4 and C-20 (class A) and can also be viewed as the oxetane ring-opened compounds of the taxane class D [19]. 

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