Butterfly, monarch

For trisubstituted olefins, the nucleophile attacks predominantly at the less substituted end of the allyl moiety, e.g. to afford a 78 22 mixture of 13 and 14 (equation 7). Both the oxidative addition of palladium(O) and the subsequent nucleophilic attack occur with inversion of configuration to give the product of net retention7. The synthesis of the sex pheromone 15 of the Monarch butterfly has been accomplished by using bis[bis(l,2-diphenylphosphinoethane)]palladium as a catalyst as outlined in equation 87. A substitution of an allyl sulfone 16 by a stabilized carbon nucleophile, such as an alkynyl or vinyl system, proceeds regioselectively in the presence of a Lewis acid (equation 9)8. The... 

Some insects can protect themselves against the toxins present in their food plants by storing them. One example is the monarch butterfly, the caterpillars of which store potentially toxic cardiac glycosides obtained from a food plant, the milkweed (see Harborne 1993). Subsequently, the stored glycosides have a deterrent effect upon blue jays that feed upon them. 

The HPLC analysis of milkweed, the food-plant source for Monarch butterflies, demonstrates that it contains a complex mixture of carotenoids including lutein, several other xanthophylls, xanthophyll epoxides, and (3-carotene, Figure 25.3b. There is a component in the leaf extract that is observed to elute near 8min, which has a typical carotenoid spectrum but is not identical to that of the lutein metabolite observed at near the same retention time in the extracts from larval tissue. 

This sequential substitution of the chloro and acetoxy groups makes the chloroacetates useful as building blocks. An example of the use of the chloroacetate 34 from isoprene for the synthesis of the Monarch butterfly pheromone is given in Scheme 737. Two different nucleophiles, sodium dimethyl malonate and sodium methyl acetoacetate, were employed in Pd(0)-catalyzed allylic substitutions. The transformation of 34 to 36 was also made... 

The fragmentation is stereospecifically anti as shown by complementary geometry obtained in the cleavage of the epimeric pair of epoxycyclobutanones 91 and 92 (Eq. 110). The fragmentation product 93 of cyclobutanone 91 is transformable into the dimethyl ester of the pheromone of the Monarch butterfly. Considering the availability of the starting epoxy ketones from enones, the oxasecoalkylation serves to reorient the oxidation pattern with chain extension as summarized in Eq. 111. 

A classical example of sequestration is the monarch butterfly Danaus plexip-pus (Danainae) which feeds on leaves oiAsclepias curassavica (Asclepiadaceae) and sequesters cardenolides such as calotropin (158) (Fig. 29). This molecule was shown to afford the butterfly an efficient protection against birds [150-152]. It was also demonstrated that its resistance to cardiac glycosides is due to a single amino acid mutation in the ouabain-binding site of the Na+/K+ ATPase [153,154]. 

The relationship between milkweeds and the monarch butterfly demonstrates a synergistic relationship between a plant and an insect (Harborne, 1993). The larvae of the monarch butterfly feed on milkweeds and accumulate cardenolides. Birds feeding on the caterpillars, pupae, or adults, will vomit and subsequently become averted and thus avoid the monarch butterflies. Interestingly, other butterflies, such as viceroy, which do not feed on milkweed, have evolved with nearly identical color pattern (mimicry), so birds avoid these nontoxic insects as well. 

At overwintering sites of the monarch butterfly [Danaus plexippus) in Mexico, only one of the three local mouse species, Peromyscus melanotis, actually feeds on the butterflies. The monarchs contain cardiac glycosides (CG) and pyrrolizidine alkaloids (PA). All three species of mice have similarly low avoidance thresholds to PA (specifically, monocrotaline). But P. melanotis is less sensitive to CG (specifically, digitoxin) than the other two, Reithrodontomys sumichrasti and Peromyscus aztecus. Laboratory tests indicate that PA is toxic to young mice. 

Mice Peromyscus spp., Reithrodontomys Monarch butterfly Cardiac glycosides and PA Glendinning, etal., 1990... 

Brower, L. P., Nelson, C. J., Seiber, J. N., Fink, L. S. and Bond, C. (1988). Exaptation as an alternative to coevolution in the cardenolide-based chemical defense of monarch butterflies (Danaus plexippus L.) against avian predators. In Chemical Mediation of Coevolution, ed. K. C. Spencer, pp. 447-475. San Diego, CA Academic Press/Harcourt Brace. 

Glendinning, J. F., Brower, L. P., and Montgomery, C. A. (1990). Responses of three mouse species to deterrent chemicals in the Monarch butterfly. I. Taste and toxicity tests using artificial diets laced with digitoxin or monocrotaline. Chemoecology 1,114-123. 

Glycoside diversification also has occurred in the coevolution of monarch butterflies and milkweeds (7). It may be desirable to relate the toxicity of cardenolides to the hydrolytic capabilities of susceptible and nonsusceptible insects. Cardenolides from Rsclepias species can be hydrolyzed by 3-glucosidases present in the plant (6), yet specialized Danans species are able to sequester these compounds, a process wh ich requires control of hydrolysis. 

Three 3-alkyl-2-methoxypyrazines (24b, 24c, and 24d) are detected as odor components in the monarch butterfly, Danaus plexippus (Table III). The wide variability in pyrazine content observed with this insect is correlated with similar variability in the larval food plants, Asclepias sp. It seems possible that the pyrazines may be one of the factors implicated in the food choice mechanism (69). 

Cardenolldes appear to be metabolized by a variety of species, possibly as a mechanism for converting these steroids into compounds that can be efficiently sequestered. The milkweed bug, Oncopeltus fasclatus, metabolizes (hydroxylates ) the nonpolar cardenollde dlgltoxln to more polar compounds that are subsequently sequestered In the dorsolateral space fluid (17. 18). Larvae of another cardenolide-adapted Insect, the monarch butterfly, Danaus plexlppus. also convert these steroids Into compounds that are readily sequestered. For example, uscharldln, which contains a carbonyl group at C-3 ( ) of the... 

Rothschild, M., Moore, B. R and Vance Brown, W. (1984). Pyrazines as warning odour components in the Monarch butterfly, Danaus plexippus, and in moths of the genera Zygaena and Amata (Lepidoptera). Biological Journal of the Linnaean Society 23 375-380. 

Fig. 3.1 The shapes and patterns of some pleasing designs found in nature or constructed as artifacts (a) the flower of the black-eyed Susan. RmJbetkia hirin, lb) the flower, stem, and leaves of the black-eyed Susan (c) a red eft, Notophtluilrrws vintlescens (d) a cut diamond (c) a paisley tie (f) a snail shell. Cepea ne/noralis (g) a monarch butterfly, Daniws plexippiix (h) a suspension bridge. Which are truly symmetrical ...

One species, the monarch butterfly (Danaus plexippus), anomalous by virtue of its migratory habits, is exceptional also in that it visits PA-containing plants and sequesters PAs, but fails to produce a pheromonal pyrrolizidine (Meinwald et al., 1968 Pliske, 1975a Edgar et al., 1971, 1976a). Such an exception does not obscure the central fact that danaines, as a group, show male sequestration... 

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