Bicyclic diterpene

Carboxylative TMM q cloaddition has also been realized with 3-methoxytropone and precursor (56) to produce an epimeric mixture of acids (122), which was employed in a synthetic study of the bicyclic diterpene sanadaol (123). The use of bi-dentate ligand tpdp (12) and high pressure did not improve the reaction. However, the addition of MesSnOAc as a co-catalyst did produce a better yield of (122) (Scheme 2.33) [16]. 

Bicyclic diterpenes-clerodanes. An important group of Insect antifeedants are the clerodane diterpenoids, which have been isolated from several different plant families (13)(Figure 1). Particularly well studied are the antifeedant activities of caryoptln and clerodin, and their derivatives, from Clerodendron and Caryopteris, Verbenaceae, against the tobacco cutworm Spodoptera litura L. (25-27). 

Unknown until recently, and still far from understood. In 1982, Alfredo Ortega and his associates isolated a bicyclic diterpene, C23 H28O8, from material gathered in Oaxaca and named it salvinorin. Another group, led by Leander Valdes at the University of Michigan, independently isolated the same compound and named it divinorum. Because Ortega published first, the name salvinorin has precedence. Neither author tested salvinorin for human activity, but recent tests by Daniel Siebert and others, myself included, have proved the psychoactivity of salvinorin beyond further doubt. 

However, various bi- and tri-cyclic diterpenes have been isolated from other Salvia species.Extraction of the leaves of 5. divinorum has now yielded a novel bicyclic diterpene, salvinorin (1), C23H28O8 whose structural elucidation forms the subject of this paper. 

Hirukawa, T., Shudo, T., Kato, T. Synthesis of secotrinervitanes, unique bicyclic diterpenes from termites. J. Chem. Soc., Perkin Trans. 1 1993,217-225. 

Mono- and Bicyclic Diterpenes derived from Phytane... 

Cocarcinogenic Diterpenes from the Euphorbiaceae and Thymelaeaceae Bicyclic Diterpenes Manool Derivatives Labdane Derivatives Clerodane Derivatives Tricyclic Diterpenes... 

GGPP is cyclized via two paths to produce the phosphate esters of the antipodal bicyclic labdadienols, thought to serve as precursors of the large majority of known bicyclic diterpenes (Hanson, 1971,1973) (Fig. 22.8). Little direct mechanistic evidence concerning these cyclizations is available (West, 1981). The initial cyclization steps yield labdane derivatives with either a 5a,10p-configuration or a 5p,10a-configuration (Hanson, 1991). 

The bicyclic diterpenes of the Asteraceae, Euphorbiaceae, Lamiaceae, and Verbenaceae appear to have exceptional promise at the familial and generic level, but more study is needed (Seigler, 1981). 

Hanson, J. R., TTie bicyclic diterpenes, in Progress in Phytochemistry Vol. 3 (L. Reinhold and Y. Liwschitz, eds.), 231-285, Wiley-Interscience, New York, 1973. 

Braekman, J. C., Daloze, D., Dupont, A., Pasteels, J., Tursch, B., Declerq, J. P., Germain, G. and Van Meerssche, M. (1980) Secotrinervitane, a novel bicyclic diterpene skeleton from a termite soldier. Tetrahedron Letters, 21, 2761-2. 

Hanson, J.R. The bicyclic diterpenes. In Progress in Phytochemistry (Reinhold, L., and Y. Liwschitz, eds.). London Interscience Publishers of John Wiley and Sons. 1972. 

Diterpenes are a large group of C20 compounds. Their main structural types are acyclic compounds, cyclic compounds, bicyclic diterpenes and tri- and tetra-cyclic diterpenes. The cosmetic use of this group of compounds is restricted to the antioxidant properties of the phenolic diterpenes extracted from rosemary and sage. 

The bicyclic diterpene dactylomelol has been isolated from the shell-less mollusc Aplysia dactylomela [109]. Teupestalin B is a constituent of Teucrium pestalozzae [110]. 1,4-Epoxy-13-dolastene (Fig. 8) has been isolated from a.Dictyota sp. brown alga [111],... 

Ishitsuka, M., Kusumi, T, Ichikawa, A., and Kakisawa, H. (1990) Bicyclic diterpenes from two species of brown algae of the Dictyotaceae. Phytochemistry, 29, 2605-2610. 

Kazlauskas, R., Mmphy, P.T., Wells, R.J., and Bloimt J.F. (1978) A series of novel bicyclic diterpenes from Dilophus prolijicans (brown alga Dictyotaceae). Tetrahedron Lett., 19,4155-4158. 

Bowden, B.F., Coll, J.C., Liyanage, N Mitchell, S.J., Stokie, G.J., and Van Altena, I.A. (1978b) Studies of Australian soft corals. IV. A novel bicyclic diterpene from Lobophytum hedleyi. Aust. J. Chem., 31, 163-170. 

Figure 20.42 (a,b) Bicyclic diterpenic carbon skeletons encountered among Octocorallia. (Cl) and (N) indicate that there are chlorine and... 

Table 20.12 Distribution of the main bicyclic diterpenic carbon skeletons"...

Not to be confused with dolabellin, which is a bisthiazole metabolite isolated from the mollusk Dolabella auricularia. Figure 2036 Other examples of C5/C11 bicyclic diterpenes. 

We conclude this overview of the bicyclic diterpenes of Odocorallia with an original carbon skeleton consisting of a cyclobutane and a cyclotetradecane whose origin is probably an internal cyclization of a cembrane. Providen-cin, which is currently the sole representative of the bicydo [12,2,0]hexadecanes, was isolated from the sea plume Pseudopterogorgia hallos harvested in the Caribbean (Providenda Island). 

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