Naturally Occurring Compounds

Mikes and Turkova have given a classification of naturally occurring hydroxamic acids in terms of their biological function or activity. They have distinguished (a) growth factors, e.g., ferri-chromes, mycobactin, and ferrioxamines, ferrichrysins, ferrirubins, etc. (6) antibiotics, e.g, aspergillic acid, mycelianamide, albomycin, nocardamine and (c) microbial pigments such as pulcherrimin. 

For the present purpose this is not a useful scheme and the naturally occurring compounds are arranged instead in order of increasing molecular complexity. Compounds that do not contain a cyclic hydroxamic acid structure are excluded. 

The first natural products shown to be cyclic hydroxamic acids belong to the group of aspergillic acids, formed by cultures of Aspergillus flavus and related organisms. 

Pulcherrimin, the red pigment from Candida pulcherrima, is a polymeric ferric complex of pulcherriminic acid (9). The structure of 

Strelitz, H. Flow, and I. N. Ashe.shov, Arch. Biochem. Biophys. 74, 150 (1958). 

This cyclic hydroxamic acid (10) and the related demethoxy compound have been isolated from corn seedlings. Both compounds are fungistatic agents. 

Shibata, N. Ichikawa, andT. Kubota, Chem. Lett., 1979, 1301. 

Peltogynin (355) has been isolated from Acacia fasciculifera and its structure has been determined spectroscopically and by preparation from a known compound.Isolisetin dimethyl ether (356), which is related to a flavone present in the root of Jamaican dogwood, Piscidia erythrina, has been synthesized.  

9 Heterocycles containing Oxygen and/or Sulphur Atoms in each of Two or Three Rings 

Successive treatment of bis-3,3-dimethylallenyl sulphone (357) with butyl-lithium in THF at 0 °C gave a 60% yield of the dithia-adamantane (358), whose structure was confirmed by X-ray crystallography. Photolysis of thietans in the presence of a new triplet sensitizer, l,3-dimethyl-2-thioxoimidazolidine-4,5-dione, has produced interesting results for example, the spiro-xanthone (359) gave the acetate (360), but in u.v. light, and without the sensitizer, the thiopyran (361) was obtained in addition to (360). Among several flavonoids identified in a Chinese plant. Euphorbia lunulata Bge., which is used in the treatment of 

Tsukayama, T. Horie, M. Masumura, M. Nakayama, and S. Hayashi, Heterocycles, 1979, 12, 

---

Many naturally occurring compounds contain several chirality centers By an analysis similar to that described for the case of two chirality centers it can be shown that the maximum number of stereoisomers for a particular constitution is 2" where n is equal to the number of chirality centers... 

Naturally occurring compounds with carbon-metal bonds are very rare The best example of such an organometallic compound is coenzyme Bi2 which has a carbon-cobalt ct bond (Figure 14 4) Pernicious anemia results from a coenzyme B12 deficiency and can be treated by adding sources of cobalt to the diet One source of cobalt IS vitamin B12 a compound structurally related to but not identical with coen zyme B12... 

Table 3. Naturally Occurring Compounds with Characteristic Odors...

Fig. 2. Naturally occurring compounds with characteristic odors. See Table 3.

Naturally Occurring Compounds. Many derivatives of iadole are found ia plants and animals where they are derived from the amino acid tryptophan. Several of these have important biological function or activity. Serotonin [50-67-9] (12) functions as a neurotransmitter and vasoconstrictor (35). Melatonin [73-31-4] (13) production is controlled daily by the circadian cycle and its physiological level iafluences, and seasonal rhythms ia humans and other species (36). Indole-3-acetic acid [87-51-4] (14) is a plant growth stimulant used ia several horticultural appHcations (37). 

Diosphenol [490-03-9] the main constituent of buchu leaves, is an example of a naturally occurring compound with tautomeric properties (286) ... 

Aledicine. A wide variety of alkaloids (qv) contain the quinoline ring system this fact accounts, in large measure, for the extensive synthetic research reported (107). In addition to the naturally occurring compounds, a large number of synthetic quinolines, eg, (22) and (23), have been prepared and studied for use in medicine. Table 3 presents selected examples. 

T. K. Devon and A. 1. Scott, Terpenes, Vol. 11, Handbook of Naturally Occurring Compounds, Academic Press, Inc., New York, 1972. 

Plasma Inhibitors, In Vivo Anticoagulants. Fourteen naturally occurring compounds that normally exert an inhibiting effect on the activity of coagulation, platelet function, and fibrinolytic activity and complement systems have been identified within the circulating blood. 

Anthraquinone chemistry began in 1868 with the elucidation of the stmcture of the naturally occurring compound alizarin (1) (1,2-dihydroxyanthraquinone) [72-48-0] by C. Graebe and C. Liebermann. 

The same thought occurred to early chemists. However, the complete absence of naturally occurring compounds based on cyclobutadiene and cyclooctatetraene contrasted starkly with the abundance of compounds containing a benzene unit. Attempts to synthesize cyclobutadiene and cyclooctatetraene met with failure and reinforced the growing conviction that these compounds would prove to be quite unlike benzene if, in fact, they could be isolated at all. 

Isonitriles are stable, often naturally occurring, compounds that contain a divalent carbon. An example is axisonitrile-3, which can be isolated from a species of sponge and possesses anti-malarial activity. Write a resonance form for axisonitrile-3 that satisfies the octet rule. Don t forget to include formal charges. 

Icosanoids (Section 26.6) A group of naturally occurring compounds derived from unsaturated C20 carboxylic acids. 

The synthesis leading to the originally proposed structure 120 starts from Oxychelerythrine (124) as shown in Scheme 45 (85CPB1763). The structure is not identical to the naturally occurring compounds and obviously does not occur in nature. 

Figure 8.9 GMD separation of various naturally occurring compounds of wide polarity range from the same sample.

The hundreds of different pharmaceutical agents approved for use by the U.S. Food and Drug Administration come from many sources (see the Chapter 5 Focus On). Many drugs are isolated directly from plants or bacteria, and others are made by chemical modification of naturally occurring compounds, but an... 

Naturally occurring compounds called cyanogenic glycosides, such as lotau-stralin, release hydrogen cyanide, HCN, when treated with aqueous acid. The reaction occurs by hydrolysis of the acetal linkage to form a cyanohydrin, which then expels HCN and gives a carbonyl compound-fa) Show the mechanism of the acetal hydrolysis and the structure of the cyanohydrin that results. 

Esters are among the most widespread of all naturally occurring compounds. Many simple esters are pleasant-smelling liquids that are responsible for the fragrant odors of fruits and flowers. For example, methyl butanoate is found in pineapple oil, and isopentyl acetate is a constituent of banana oil. The ester linkage is also present in animal fats and in many biologically important molecules. 

The naturally occurring compound urea, CO(NH,), was first synthesized by Friedrich Wohler in Germany in 1828 by heating ammonium cyanate. This synthesis was a significant event because it was the first time that an organic compound had been produced from an inorganic substance. Urea may also be made by the reaction of carbon dioxide and ammonia ... 

Because of the presence of the 1,5-diene moiety in many naturally occurring compounds, a great deal of effort has been expended in searching for methods to... 

A list of most of the known natural compounds (e.g., terpenes, alkaloids, carbohydrates) to which structures have been assigned, along with structural formulas, melting points, optical rotations, and references, is provided in Devon and Scott, Handbook of Naturally Occurring Compounds , 3 vols.. Academic Press, New York, 1972. 

Copping, L.G. and Menn, J.J. (2000). Biopesticides A Review of Their Action, Applications, and Efficacy—A valuable account of naturally occurring compounds that act as pesticides. 

---