Bicyclic Diterpenoids

A series of andalusol derivatives (8) have been obtained17 from Sideritis foetens (Labiatae). 7a-Acetoxytranscommunic acid (9) was reported18 from Chromolaena collina. The acetate (10) and hemi-acetal (11) were described19 as constituents of 

A further group of acetals has been prepared from manool23 for structure-odour studies. Some 1,5-diepoxides in this group underwent rearrangement based on the intramolecular opening of 8p,9,3-epoxides.24 

Croton (Euphorbiaceae) species have afforded several types of diterpenoid. Penduliflaworosin (19), isolated34 from C. penduliflorus, represents a structure 

Kitagawa, T. Kamigauchi, K. Yonetani, and M. Yoshihara, Chem. Pharm. Bull., 1980, 28, 2403. 

Although the absolute configuration of these clerodanes from Croton species was not determined, the absolute stereochemistry of a number of clerodanes from Teucrium (Labiatae) species has been clarified.39 19-Acetylgnaphalin and iso-fruticolone were shown to belong to the neoclerodane series. Teuflin (24) has been obtained40 from Teucrium viscidum and details of an X-ray structure have been published.41 The structure (25), without absolute configuration, was assigned42 to 

---

Wahlberg. Tobacco chemistry. 4,6,8-Trihydroxy-11-capnosene-2,10-dione, a new cembrane-derived bicyclic diterpenoid from tobacco. Acta Chem... 

The occurrence of a group of novel bicyclic diterpenoid (155)—(158) in Dilophus prolificans (Dictyotaceae) has been reported. The structure of the acetate (158) was established by X-ray analysis. Fuscol (159) is an elemene ... 

We ve classified more than 550 diteipenoids (listed in Table 3 whith corresponding sources) from all the reported Salvia species which we ve divided into 2 categories. The first one contains the monocyclic and bicyclic diterpenoids including labdanes and clerodanes and related diterpenes. The second category concerns tricyclic and tetracyclic diterpenes including pimaranes and abietanes and related diterpenes. The clerodane type diterpenes are mainly represented by american species while abietane type are found in european and asian species. 

Cleomeolide (91) is an unusual bicyclic diterpenoid obtained156 from Cleome viscosa (Capparaceae). The Basidiomycetes contain a number of unusual terpenoid metabolites such as the cyathins. These have now been thoroughly reviewed.157... 

A number of bicyclic diterpenoids have insect anti-feedant properties and consequently the synthesis of intermediates such as (93) in this series has attracted... 

Cembranolide, a diterpene, is unique in that it is the only FPTase inhibitor isolated from a marine specimen, Lobophytum cristagalli (Order Alcyonacea, Family Alcyoniidae), that was collected at a 15m depth from Seychelles Island. The compound was isolated by silica gel chromatography followed by reverse phase HPLC and the structure of this 14/5-bicyclic diterpenoid (Figure 24) was elucidated by NMR and confirmed by X-ray crystallography [115]. 

From a taxonomically distinct and still unidentified specie of the Pseudopterogorgia genus, a related series of pseudopterosins containing bicyclic diterpenoid glycosides, 7 seco A-D, were also isolated and their structures elucidated by Look and Fenical [18]. Compounds 7 seco A-D possess potent anti-inflammatory and analgesic activities that are similar to the pseudopterosins, and also show antimicrobial activity towards the bacteria. Staphylococcus aureus. For example 7 seco-A, pseudopterosin exhibited a 69% reduction of inflammation in the mouse ear edema assay at a minimum inhibitory concentration (MIC) of 50 pg/ear. 

Cterodanes. The C. are a group of bicyclic diterpenoids with over 650 members, they occur in higher plants (especially Lamiaceae), microoiganisms, and marine oiganisms. 

Tashmukhamedova MA, Mukhina OA, Syrov VN, Khushbeiktova ZA, Katkova SP, Kosovskii MI (1992) Hypoglycemic activity of bicyclic diterpenoids of the clerodane series as compared to adebit and maninil. Problemy Endokrinologii 38(l) 48-50 (in Russian)... 

This class of bicyclic diterpenoids derive their generic name and chirality from (-)-clerodin (402), the bitter principle from the leaves and twigs of Clerodendron infortunatum (180, 328). The oleoresin of Hardmckiapinnata contains several compounds of this class, including the simplest clerodane, kolavenol... 

A total synthesis of the [12,l,0]bicyclic diterpenoid casbene (183) has been achieved, employing Ni(CO)4-induced intramolecular coupling of the doubly allylic bromide (182) to construct the necessary 14-ring. 

Nakamura, H., H. Wu, Y. Ohizumi, and Y. Hirata Agelasine-A, -B, -C, and -D, Novel Bicyclic Diterpenoids with a 9-Methyladeninium Unit Possessing Inhibitory Effects on Na,K-ATPase from the Okinawan Sea Sponge Agelas sp. Tetrahedron Lett. 25, 2989 (1984). 

Look, S.A., and W. Fenical New Bicyclic Diterpenoids from the Caribbean Gor-gonian Octocoral Eunicea calyculata. J. Org. Chem. 47, 4129 (1982). 

All natural organobromocompounds are of marine origin and have been found especially in algae. The genus Laurencia has provided a series of brominated acetylenic cyclic ethers and bromosesquiterpenes, two of which, aplysin and aplysinol, were isolated earlier from the sea hare, Aplysia kurodai. Reviews by Scheuer 160) and Premuzic (752) may be consulted and also the more recent papers 87, 93, 102, 103, 107, 128, 129, 130). A brominated bicyclic diterpenoid, aplysin-20, with unusual stereochemical features has been also isolated from Aplysia kurodai 186), and more recently unique brominated and chlorinated monoter-penes have been obtained from A. californica 85) 86). Two of them were also found as components of an extract of the alga Plocamium coccineum... 

---