Terpenes and Related Compounds

Of synthetic importance is the Wagner-Meerwein rearrangement especially in the chemistry of terpenes and related compounds." For example isoborneol 5 can be dehydrated and rearranged under acidic conditions to yield camphene 6 ... 

Starting with the simple compounds acetyl-CoA, glyceraldehyde-3-phosphate, and pyruvate, which arise via the central pathways of metabolism, the key intermediate isopentenyl diphosphate is formed by two independent mutes. It is then converted by bacteria, fungi, plants, and animals into thousands of different naturally occurring products. These include high polymers, such as rubber, as well as vitamins, sterols, carotenoids, and over 30,000 different terpenes and related compounds. Many of the latter are found only in specific plants where they may function as defensive compounds or pheromones. 

This principle represents both British and American practice, and has been followed for some years. Although a name such as methylpinane violates this principle, it is unambiguous and simpler than tetrametbylnorpinane. Also, relations among substituted pinane derivatives are more readily seen horn a series of names such as methylpinane, (chloromethyl)pinane, and methylenepinane than from a series in which methylpinane is replaced by tetrametbylnorpinane. The names of only a few terpene compounds are involved, however, in this problem and a compromise may be the best solution. For the sake of consistent nomenclature between terpenes and related compounds, sticking to a recognized principle is an important consideration. 

Commercial mixtures of the limonene molecules can also contain other terpenes, and related compounds such as p-cumene. 

CAS 138-86-3. C10H16. Commercial form is high in dipentene content, but also contains other terpenes and related compounds in varying amounts. 

In addition to the major cell wall components of cellulose, hemicellulose and lignin, wood contains varying amounts of substances termed extractives. The term extractives includes a wide range of chemical types and a very large number of individual compounds. Some of the major chemical types are 1) Terpenes and related compounds, 2) Fatty acids, 3) Aromatic compounds and 4) Volatile oils. Species differ widely in the type and amount of extractives present. Also there is considerable variation in the distribution of extractives throughout the wood of individual trees. Although some extractives are found in sapwood, the heart-wood usually contains the largest amount. 

Arigoni, D. Some Studies in the Biosynthesis of Terpenes and Related Compounds. Pure and Appl. Chem. 17, 331 (1968). 

The sensitivity of pheromone perception in bark beetles appears to be generally typical of the very high sensitivity shown by many insects to their pheromones (Seabrook, 1978 Payne, 1979 see also Mustaparta, Chapter 2). In general, beetles have a lower threshold for their own pheromonal components than to other terpenes and related compounds (Mustaparta et al., 1979 Dickens, 1981). In I. pini, receptor cells specialized for pheromone perception respond minimally, if at all, to host compounds, and vice versa (Mustaparta et al., 1979,1980). However, the behavioral interruption of the response of I. pini to (- )ipsdienol by a few percent of (+ )ipsdienol or by ipsenol must be due to processing in the central nervous system of the insect and not to any interaction of compounds at the antennal receptor sites. Similarly, the synergistic effect of a pheromone blend is due to central integration. 

Terpenes and related isoprenoid compounds are biosynthesized from isopentenyl pyrophosphate... 

Plant metabolism can be separated into primary pathways that are found in all cells and deal with manipulating a uniform group of basic compounds, and secondary pathways that occur in specialized cells and produce a wide variety of unique compounds. The primary pathways deal with the metabolism of carbohydrates, lipids, proteins, and nucleic acids and act through the many-step reactions of glycolysis, the tricarboxylic acid cycle, the pentose phosphate shunt, and lipid, protein, and nucleic acid biosynthesis. In contrast, the secondary metabolites (e.g., terpenes, alkaloids, phenylpropanoids, lignin, flavonoids, coumarins, and related compounds) are produced by the shikimic, malonic, and mevalonic acid pathways, and the methylerythritol phosphate pathway (Fig. 3.1). This chapter concentrates on the synthesis and metabolism of phenolic compounds and on how the activities of these pathways and the compounds produced affect product quality. 

Section 26.8 X fi-Thujone a toxic monoterpene present in absinthe Terpenes and related isoprenoid compounds are biosynthesized from isopentenyl pyrophosphate. 

Isoprenoid structures for carotenoids, phytol, and other terpenes start biosynthetically from acetyl coenzyme A (89) with successive additions giving mevalonate, isopentyl pyrophosphate, geranyl pyrophosphate, farnesyl pyrophosphate (from which squalene and steroids arise), with further build-up to geranyl geranyl pyrophosphate, ultimately to a- and /3-carotenes, lutein, and violaxanthin and related compounds. Aromatic hydrocarbon nuclei are biosynthesized in many instances by the shikimic acid pathway (90). More complex polycyclic aromatic compounds are synthesized by other pathways in which naphthalene dimerization is an important step (91). 

During the developing work which has led to the mature report here given, there have been three long typescript versions of the terpene nomenclature report (April, 1949, June, 1950, and June, 1952, respectively) and one condensed typescript version (September, 1953). In addition the work was presented briefly by Miss Grafflin under the title Nomenclature of Terpene Hydrocarbons and Related Compounds at a Symposium on Nomenclature of Hydrocarbons held in 1949 by the ACS Division of Petroleum Chemistry and preprinted along with the other papers of this symposium. Furthermore, Austin M. Patterson presented a preview of this nomenclature in his column in Chemical and Engineering News (Cbem. Eng. News 30, 930-5(1952)) It should be noted that the present report differs in some respects from the proposals in these earlier, more or less widely circulated versions. 

Some aspects of the photochemical behaviour of terpene have been investigated to evaluate some of the source materials in air pollution. A computational study of the Z, -isomerism of buta-1,3-diene, hexa-l,3,5-triene and related compounds has been reported. An ab initio study of the photo-cyclisation paths of buta-1,3-diene has been carried out. Calculations have... 

FIGURE 26.6 Some representative terpenes and related natural products. Structures are customarily depicted as carbon skeleton formulas when describing compounds of isoprenoid origin. 

Two German chemists, Heinrich Otto Wieland (1877-1957) and Adolf Windaus (1876- ), worked out the structure of steroids and related compounds. (Among the steroids are a number of important hormones.) Another German chemist, Otto Wallach (1847-1931), painstakingly elucidated the structure of terpenes, important plant oils (of which menthol is a well-known example), while still another, Hans Fischer (1881-1945), established the structure of heme, the coloring matter of blood. 

Biosynthesis of ipomoeamarone and related compounds in sweet potato root llpomoea batatas Lam.) infected with Ceratocystis fimbria-ta. Conversion of acetate to farnesyl pyrophosphate (see Terpenes) occurs in the uninfected plant, and is stimulated by infection. All reactions marked with an asterisk are absent before infection. [P.A.Brindle 8i D.R.Threlfall Biochem. Soc. Trans. 11 (1983) 516-5221... 

Noma, Y., E. Akehi, N. Miki, and Y. Asakawa, 1992a. Biotransformation of terpene aldehyde, aromatic aldehydes and related compounds by Dunaliella tertiolecta, 31 515 517. 

Noma, Y. and M. Iwami, 1994. Separation and identi cation of terpene convertible actinomycetes S. bottro-pensis SY-2-1, S. ikutamanensis Ya-2-1 and S. humidus Tu-1. Bull. Tokushima Bunri Univ., 47 99-110. Noma, Y., F. Kamino, T. Hashimoto, and Y. Asakawa, 2003. Biotransformation of (+)- and (-)-pinane-2,3-diol and related compounds hy Aspergillus niger. Proceedings of the 47th TEAC, pp. 91-93. 

---