Diterpene lactone

Some representative Claisen rearrangements are shown in Scheme 6.14. Entry 1 illustrates the application of the Claisen rearrangement in the introduction of a substituent at the junction of two six-membered rings. Introduction of a substituent at this type of position is frequently necessary in the synthesis of steroids and terpenes. In Entry 2, formation and rearrangement of a 2-propenyl ether leads to formation of a methyl ketone. Entry 3 illustrates the use of 3-methoxyisoprene to form the allylic ether. The rearrangement of this type of ether leads to introduction of isoprene structural units into the reaction product. Entry 4 involves an allylic ether prepared by O-alkylation of a (3-keto enolate. Entry 5 was used in the course of synthesis of a diterpene lactone. Entry 6 is a case in which PdCl2 catalyzes both the formation and rearrangement of the reactant. 

The germination regulation effects of ten sesquiterpene lactones, the flavonoid artemetin and the diterpene lactone, 17-acetoxyacanthoaustralide, on 12 crop and weed seeds are presented. 

Zheng J. Screening of active anti-inflammatory, immunosuppressive and anti-fertility components of Tripterygium wildfordii III. A comparison of the anti-inflammatory and immunosuppressive activities of 7 diterpene lactones epoxides compounds in vivo. Zhongguo Yixue Kexueyuan Xuebao 1991 13 391-397. 

Patarapanich C, Laungcholatan S, Mahaverawat N, Chaichantipayuth C, Pummangura S. (2007) HPLC determination of active diterpene lactones from Andrographis paniculata Nees planted in various seasons and regions in Thailand. Thai J Pharm Sci 31 91-99. 

Higher plants and some microorganisms produce a number of diterpene lactones such as podolactones A-E, ponolactones A and its glucoside, inumakilactones A, its glucoside, B and E, nagi-latone C, momilactones A-C, and sellowin A, many of which are inhibitory to the growth of plants (Table 5). 

On the other hand, the epoxides obtained by caction of ketones with I equiv. of 2 react with a large variety of nucleophiles. Thus this method was used to synthesize the diterpene lactone isomarrubiin (6, equation I). 

Recently a collection and chemical examination of Aplysia Juliana from the intertidal zone of the Karachi, Pakistan coastline yielded a new diterpene lactone—angasiol acetate [26], the... 

Nakatani, N.R. and Inatani, R. 1983. A new diterpene lactone, rosmadial from rosemary. Agric. Biol. Chem. 47 353-358. 

Paquette, L.A., Wang, T.-Z., Wang, S., and PhiUppo, C.M.G., Enantioselective synthesis of (+)-cleomeolide, the structurally unique diterpene lactone constituent of Cleome viscosa. Tetrahedron Lett., 34, 3523, 1993. 

Paquette, L.A., Wang, T.-Z., Philippo, C.M.G., and Wang, S., Total synthesis of the cembranoid diterpene lactone (-i-)-cleomeolide. Some remarkable conformational features of nine-membered belts linked in a 2,6-fashion to a methylenecyclohexanc core, J. Am. Chem. Soc., 116, 3367, 1994. Moskva, V.V., and Razumov, A.I., Phosphinic and phosphinous acids. Part 34. Phosphorylated 1,3-dioxolanes, Trans. Kazan. Khim.-Tekhnol. Inst., 34, 273, 1965 Chem. Abstr, 68, 39729y, 1968. Razumov, A.L, and Gurevich, P.A., Synthesis of phosphorylated 1,3-dioxoles, Zh. Obshch. Khim., 38, 944, 1968 J. Gen. Chem. USSR (Engl. Transl.), 38, 909, 1968. 

H. (+)-CLEMEOLIDE, THE STRUCTURALLY UNIQUE DITERPENE LACTONE CONSTITUENT OF CLEOME VISCOSA... 

The herb Cleome viscosa (syn. cleome icosandra)y which is widely distributed in India, has long been recognized by the native population to serve as a rubefaciant, vesicant, and anthelmintic agent. As a consequence of these reputed properties, three research groups undertook almost simultaneously in the late 1970 s to determine the principal active constituent of this sticky, odoriferous plant [82,83]. On the basis of the NMR, X-ray, and CD data, the substance was determined to be the macrocyclic diterpene lactone 160 and named cleomeolide. The structural features of this macrolide are unusual in several respects (a) the double bond positioned a,p to the lactone carbonyl resides at a bridgehead site, a... 

This diterpene lactone, bacchotricuneatin A was also isolated from B. tricuneata [24] and Baccharis cassinaefolia D. C. [25],... 

Fig. (62). Structure of an antimicrobial diterpene lactone isolated from Baccharis genistelloides...

Latrunculin B was also present in extracts of C. hamiltoni collected from the reefs off southern Mozambique. The latter specimens of C. hamiltoni also yielded two spongiane diterpene lactones (150,151) [127]. No evidence of the hamiltonins was found in extracts of the Mozambique specimens of C. hamiltoni and possibly reflects geographical variation in the organisms that make up C. hamiltonf s diet in this region of the southern African coast. The structures of both spongiane diterpenes and the hamiltonins A -E were determined from spectroscopic data while the absolute stereochemistry at C-16 in 147 was established by comparison of its CD data with those of related compounds [127]. 

The macrocyclic diterpene lactone, cleomeolide (1) was first isolated by us [9,10] in the late 1970s and its complete structure and stereochemistry were determined by means of NMR, X-ray and CD methods. Burke et al. 

In the course of the search for novel potent anti-AIDS agents, the ethanolic extract of the roots of T. wilfordii was found to show significant anti-HIV activity. Bioassay-directed fractionation of the active extract has led to the isolation and characterization of a new anti-HIV principle, a kaurane-type diterpene lactone, tripterifordin (90), Fig (27). This compound inhibited HIV replication in H9 lymphoc e cells with an EC50 of 1 pg/ml (6 (M) but it did not inhibit uninfected H9 cell growth at 15 xM [180]. From the same species a new kaurene type diterpene, neotripterifordin (91) was also isolated, which showed potent anti-HIV replication activity in H9 lymphocyte cells with an EC50 of 25 nM and a... 

In the past 20 years hundreds of Chinese traditional and herbal medicines with immunomodulating functions have been screened, and their active components studied. Through these studies, six diterpene lactone epoxide compounds, with antiinflammatory and immunosuppressive actions, were isolated from T. wilfordii. Zheng et al. [183] assayed the half-effective dose (ED50), the therapeutic index (TI) and a certain safety factor (CSF) using croton oil induced ear swelling and hemolysin-antibody formation mouse models and found that triptolide (79), tripdiolide (80), triptonide (81), tripchlorolide (92), and triptolidenol (93) possessed both antiinflammatory and immunosuppressive activities, while triptriolide (94) showed antiinflammatory action only. Fig. (28). The results of the TI and CSF of both activities clearly demonstrated that the antiinflammatory and immunosuppressive compounds in T. wilfordii are pluralistic and the differences in these compounds can be used as a base for the evaluation and selection of them. 

Numerous diterpenes with the briarane skeleton are isolated from sea fans, sea feathers, and soft corals, e. g. briarein A, a chlorinated diterpene lactone from the gorgonian Briareum asbestinum ( 301139010,3, Mr 643,08) or E. (C26H3,C10,o, Mr 538.98) from the sea fan Erythropodium cartbaeorum, which is formed by a di- r-methane rearrangement from E. B (C26H3 C10,o, Mr 538.98). The compounds have antiinflammatory activities. 

Zainutdinova UN, Pulatova MP, Badalbaeva TA, Ummova RU, Mavlyankulova ZI, Pulatova TP, Aslanova KhA (1994) Diterpene lactones and iridoid glycosides of plants of the genus LagochUus. Chem Nat Compd 30(l) 27-30... 

---