Diterpenoid

Synthetic and mechanistic aspects of iatramolecular cycli2ation in the tricycHc diterpenoid area have been studied in detail. In general, the presence of electron withdrawing groups such as carbonyl in the side chain retard the rates of cycli2ation (61). 

The synthesis of cafestol, an antiinflammatory agent which occurs in coffee beans along with related diterpenoids such as actractyloside and kahweol, was accomplished by the same strategic approach which was applied to its companion atractyligenin. 

Kahweol, a "coffee" diterpenoid, was synthesized from the co-occurring natural product cafestol. 

Diisocyanoadociane, a novel marine-derived diterpenoid, was analyzed retrosynthetically using the intramolecular Diels-Alder transform as T-goal concurrently with topological and stereochemical guidance. The enantioselective synthesis outlined below allowed assignment of absolute configuration. 

Heterocycles in synthesis of drimane sesquiterpenoids from labdane diterpenoids 97IZV896. 

Chemistry of taxol, anticancer diterpenoid with oxethane cycle as a part of fused system 98PAC331. 

Furosclerodanes (diterpenoids including furan or y-butyrolactone cycle) from Teucrium genus 9814(48)2185. 

Synthesis of paclitaxel and resiniferatoxin analogs, diterpenoids with oxetane fragments 97G461. 

Total synthesis of taxoids, diterpenoids with 0-heterocyclic fragments 97H(46)727. 

Terpenoids are classified according to the number of five-carbon multiples they contain. Monoterpenoids contain 10 carbons and are derived from two isopentenyl diphosphates, sesquiterpenoids contain 15 carbons and are derived from three isopentenyl diphosphates, diterpenoids contain 20 carbons and are derived from four isopentenyl diphosphates, and so on, up to triterpenoids (C30) and tetraterpenoids (C40). Monoterpenoids and sesquiterpenoids are found primarily in plants, bacteria, and fungi, but the higher terpenoids occur in both plants and animals. The triterpenoid lanosterol, for example, is the precursor from which steroid hormones are made, and the tetraterpenoid /3-carotene is a dietary source of vitamin A (Figure 27.6). 

The terpenoid precursor isopentenyl diphosphate, formerly called isopentenyl pyrophosphate and abbreviated IPP, is biosynthesized by two different pathways depending on the organism and the structure of the final product. In animals and higher plants, sesquiterpenoids and triterpenoids arise primarily from the mevalonate pathway, whereas monoterpenoids, diterpenoids, and tetraterpenoids are biosynthesized by the 1-deoxyxylulose 5-phosphate (DXP) pathway. In bacteria,... 

Diterpenoids are derived biosynthetically from geranylgeranyl diphosphate (GGPP), which is itself biosynthesized by reaction of farnesvl diphosphate with isopentenyl diphosphate. Show the structure of GGPP, and propose a mechanism for its biosynthesis horn FPP and IPP. 

The benzannulation reaction of ethynylferrocene 120 with the diterpenoid chromium alkoxycarbene 119 leads to novel diterpenoid ferrocenyl quinones 121 which, due to their electron-transfer properties, are regarded as potential candidates for non-linear optical materials [71] (Scheme 52). 

Tokoroyama T. Synthesis of Clerodane Diterpenoids and Related Compounds -Stereoselective Construction of the DecaUn Skeleton With Multiple Contiguous Stereogenic Centers Synthesis 2000 611-633... 

Keywords diterpenes, stereoseiective construction of the decaiin skeieton of cierodane diterpenoids... 

Bruno M, Piozzi F, Rosselli S. Natural and hemisynthetic neoclerodane diterpenoids from Scutellaria and their antifeedant activity. Nat Prod Rep 2002 19 357-78. 

Makinoa crispata (Steph.) Miyake from Japan was shown by Hashimoto et al. (1989) to contain diterpene derivatives of the sort illustrated as [466-469] (see Fig. 5.7 for stractures). More recently, Liu and Wu (1997) reported the presence of the rearranged abietane-type diterpenoid derivative makanin [470] from plant material of M. crispata collected on Taiwan. Of note was the apparent absence of any of these compounds in the Japanese plants. 

Leong, Y.-W. and Harrison, L. J. 1997. ent-Trachylobane diterpenoids from the liverwort Mastigophora diclados. Phytochemistry 45 1457-1459. 

Liu, H.-J. and Wu, C.-L. 1997. A rearranged abietane-type diterpenoid from the liverwort Makinoa crispata. Phytochemistry 44 1523-1525. 

Yu Z, GR Stewart, W Mohn (2000) Apparent contradiction psychrotolerant bacteria from hydrocarbon-contaminated arctic tundra soils that degrade diterpenoids synthesized by trees. Appl Environ Microbiol 66 5148-5154. 

Smith DJ, VJJ Martin, WH Mohn (2004) A cytochrome P450 involved in the metabolism of abietane diterpenoids by Pseudomonas abietaniphila BMKE-9. J Bacterial 186 3631-3639. 

Hanson JR, PB Reese, JA Takahashi, MR Wilson (1994) Biotransformation of some stemodane diterpenoids by Cephalosporium aphidicola. Phytochem 36 1391-1393. 

Martin VJJ, WW Mohn (2000) Genetic investigation of the catabolic pathway for degradation of abietane diterpenoids by Pseudomonas abietaniphila BKME-9. J Bacteriol 182 3784-3793. 

Sultankhodzhaev et al. (2005) reported tyrosinase inhibition studies on 15 diterpenoid alkaloids with the lycoctonine skeleton, and their semisynthetic... 

Table 2 Tyrosinase inhibitory activities of the diterpenoid and napelline type alkaloids and their derivatives [49]...

Sultankhodzhaev MN et al. (2005) Tyrosinase inhibition studies of diterpenoid alkaloids and their derivatives structure-activity relationships. Nat Prod Res 19(5) 517-522... 

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