Terpenoids structures

Scheme 13.6 is a retrosynthetic outline of the syntheses in Schemes 13.7 to 13.9. The common feature of these syntheses is the use of terpene-derived starting materials. The use of such a starting material is suggested by the terpenoid structure of juvabione, which can be divided into isoprene units. ... 

While the unbranched 204-207 clearly originate from the acetate pool, the structure of ( )-3,7-dimethyl-2-octene-l,8-dioic acid, callosobruchusic acid 207, a female produced copulation releasing pheromone of the azuki bean weevil, Callosobruchus chinensis [374] points to a terpenoid structure. The synthetic enantiomers [375] proved to be equally effective in releasing copulation behaviour in males. 

IPP and DMAPP are reactive hemiterpene intermediates in the pathways leading to more complex terpenoid structures. They are also used as alkylating agents in the formation of meroterpenoids as indicated above, but examples of these structures are discussed under the section appropriate to the major substructure, e.g. alkaloids, shiki-mate, acetate. Relatively few true hemiterpenes are produced in nature, with isoprene, a volatile compound which is released by many species of plants, especially trees, being the notable example. Isoprene is formed by loss of a proton from the allylic cation (Figure 5.7). 

Birch, A. J., R. J. English, R. A. Massy-Westropp and H. Smith Studies in relation to biosynthesis, 15. Origin of terpenoid structures in mycelianamide and mycophenolic acid. J. Chem. Soc. 369 (1958). 

Mariani, E Ixtngobardi, M., Schenone, P Bondavalli, F., and Bianchi, C., Acetylenic Mannich bases with terpenoid structure, Chim. Ther. 8,281. 1973. 

Hanson Jr. The development of strategies for terpenoid structure determination. Nat. Prod. Rep. 2001 18 607-617. 

The novel heliannane-type sesquiterpenoid (-)-heliannuol E was synthesized in the laboratory of K. Shishido. Interest in the total synthesis of this natural product was not only spurred by its irregular terpenoid structure and significant biological activity but the need to establish the absolute stereochemistry at the C2 and C4 stereocenters. The Sonogashira reaction was utilized to prepare the 3-arylpropargyl alcohol by coupling of a heavily substituted aryl iodide with an unprotected propargyl alcohol in quantitative yield. 

Thousands of different terpenoid structures occur in perfume ingredients, both natural and synthetic. The chemistry of terpenoids is rich and varied, and attempts to understand it have, on many occasions, contributed... 

During processing of turpentine and other terpene sources, often a variety of acid-catalysed reactions and aerial oxidations occur. / -Cymene is often produced as a result of these processes since it is one of the most thermodynamically stable of terpenoid structures, ft does occur in essential oils and fragrances, but its main uses are as a thermally stable heat transfer fluid and as a precursor for musks (see Section 4.3). 

This type of alkylation reaction is very important in the synthesis of terpenoids as it represents a method for the introduction of gem-dimethyl groups, a common feature of terpenoid structure. An example of this strategy in action is shown in Figure 6.20. 

The terpenoids form the largest group of natural odorants and so it is only to be expected that they also form the largest group of modern fragrance ingredients. Thousands of different terpenoid structures, both natural and synthetic, will be found in perfumes from fine fragrance to household cleaners. Some of the more important ones are shown in Table 9.1. 

Mayol (10.39) has an overall shape rather reminiscent of that of Lilial but has a terpenoid structure similar to that of hydroxycitronellal... 

Some natural products containing a furan ring have an intense odour, e.g. 2-furylmethanethiol 27, a component of coffee aroma, rose furan 28, a component of rose oil, and menthofuran 29, which occurs in peppermint oil. The compounds 28 and 29 are reminiscent of terpenoid structures ... 

C.d. data for steroid and terpenoid structures which include a seven-membered (c)-lactam ring have afforded correlations between the Cotton effect (at 210—230 nm) and structure which reveal limitations to the scope of Ogura s chirality rule (Figure 5). Fusion to additional rings via the 4,5- or 5,6-positions gives e-lactams which generally obey the earlier rule , but 3,4- or 6,7-ring... 

This defect was overcome by exchanging the unstable terpenoid structure with a 4-phenoxyphenyl group. Fenoxycarb (9), a carbamate with a 4-phenoxyphenyl group, was the first compound developed for agricultural use [12]. TTie ether compound pyriproxyfen (10) was found later by Sumitomo Chemical [13]. 

Many ortho- and para-quinones based on terpenoid structures are found in the Lamiaceae (Labiatae, the mint family) especially in the genus Salvia (4,19,20) (Fig. 6.3), the Malvaceae (Gossypium and Hibiscus), the Bombacaceae Bom-bax), Boraginaceae (Cordia, 21-25), the Asteraceae Cac-alia) (26, 27), as well as other families. The wood of the blue mahoe. Hibiscus elatus (Malvaceae), has a dark bluish... 

Irving, R. S. and R. P. Adams, Genetic and biosynthetic relationships of monoterpenes, in Terpenoids Structure, Biogenesis and Distribution (V. C. Runeckles and T. J. Mabry, eds.). Recent Advances in Phytochemistry Vol. 6,187-214, Academic Press, New York, 1973. 

A large number of alkaloids are based on terpenoid structures. In most instances, the source of the nitrogen is not established, but the remaining portions of the molecule typi-... 

It is clear from the mechanism shown in Figure 6.14 that terpenoid structures will always contain a multiple of ve carbon atoms when they are rst formed. The rst terpenoids to be studied contained 10 carbon atoms per molecule and were called monoterpenoids. This nomenclature has remained and so those with 5 carbon atoms are known as hemiterpenoids those with 15, sesquiterpenoids those with 20, diterpenoids and so on. In general, only the hemiterpenoids, monoterpenoids, and... 

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