Terpenoids. XIII.<sup>1</sup> The Structures of the Cactus Triterpenes Machaeric Acid and Machaerinic Acid<sup>2</sup>

Djerassi, Carl; Lippman, A. E.

doi:10.1021/ja01612a033

Cited by 33 publications

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“…Although many investigators have contributed to our knowledge of the chemistry of columnar cacti, two individuals stand out: Carl Djerassi and Henry Kircher. Djerassi's work in the 1950s and 60s includes some of the original chemical descriptions of cactus alkaloids and triterpenes (Djerassi and Lippman, 1955;Djerassi et al, 1953aDjerassi et al, , b, 1954aDjerassi et al, , b, 1955Djerassi et al, , 1957Djerassi et al, , 1958Djerassi et al, , 1962. Kircher was a collaborator of Bill Heed and was specifically involved in the chemistry of the cactus-microorganism-Drosophila model system from its inception in the early 1960s (Kircher, 1977(Kircher, , 1980(Kircher, , 1982Kircher and Bird, 1982).…”

Section: Allelochemistry Of Columnar Cactimentioning

confidence: 99%

Chemical Interactions in the Cactus-Microorganism-Drosophila Model System of the Sonoran Desert1

Fogleman

Danielson

2001

American Zoologist

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SYNOPSIS. The Cactus-Microorganism-Drosophila Model System of the Sonoran Desert represents an excellent paradigm of the role of chemistry in plant-animal interactions. In this system, four species of endemic Drosophila feed and reproduce in necrotic tissue of five species of columnar cacti. Studies over the past 35 yr have characterized a myriad of interactions between the three major components of the model system. The cacti contain a variety of allelochemicals which are primarily responsible for the highly specific pattern of host plant utilization exhibited by the desert Drosophila. Plant chemistry, through its effect on the microbially produced volatile patterns, is further involved in host specificity because the flies use the volatile pattern to cue in on necroses in the appropriate species of cactus. The metabolic activities of microorganisms (bacteria and yeasts) living in the necrosis can affect the substrate chemistry in both positive and negative ways (i.e., acting to increase or to decrease the toxicity of the substrate). Finally, cactus chemistry may affect drosophilid mating behavior since larval rearing substrate has been shown to influence adult hydrocarbon epicuticular composition. In D. mojavensis, adult hydrocarbon profile has been implicated as a determinant of mate choice leading to premating isolation between geographically isolated populations that use chemically different cactus substrates. Current research is focused on the evolution and regulation of genes whose products (cytochrome P450 enzymes) are involved in the specific insect-host plant relationships which exist between the Drosophila species and the cactus species.There are many reasons why investigators choose to focus their research efforts on what are referred to as ''model systems.'' Typically included among these would be the idea that model systems are easier to study because they are less complex than other scientific situations. At the same time, model systems should be representative of more complex, natural systems so that information that is obtained from their study is broadly applicable. For almost a century, the fruit fly, Drosophila melanogaster, has served as a model organism for the study of genetics. As a genetic paradigm, Drosophila is more tractable to scientific investigation than most organisms and has provided important insights into a wide variety of human maladies from alcohol abuse to neurological brain disorders (Bellen, 1998). Similarly, the interrelationships of the columnar cacti and the cactophilic Drosophila species of the Sonoran Desert have, for the past 35 yr, provided an excellent model system with which to study relevant questions in evolution, ecological genetics, and chemical ecology. The intent of this article is to briefly review and characterize the chemical interactions between the plants (cacti) and animals (Drosophila) of this model system, and, in addition, provide some thoughts on possible future directions for integrative approaches in this research area.

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Section: Allelochemistry Of Columnar Cactimentioning

confidence: 99%

Chemical Interactions in the Cactus-Microorganism-Drosophila Model System of the Sonoran Desert1

Fogleman

Danielson

2001

American Zoologist

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“…The product proved t o be a monomethyl ester. I t has previously been observed in other trlterpenoids (13,14,15,16) that the presence of an appropriately situated oxygen function can greatly facilitate the hydrolysis of an otherwise very resistant ester. This observation suggested that the carbomethoxyl group which underwent hydrolysis should be placed as in (VI, R = RIe), a part structure which already assumed a general familiarity, but a more direct demonstration of this relationship was required.…”

Section: Hooc )mentioning

confidence: 97%

Terpenoids: V. Senegenin: Functional Groups and Part Structure

Dugan¹,

Mayo²,

Starratt³

1964

Can. J. Chem.

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Senegenin, the sapogenin from Polygala senega has been shown to contain chlorine; it has the empirical formula C30H4506Cl. The oxygen atoms, contrary to earlier work, are contained in two carboxyl groups and two secondary hydroxyl groups. There is one isolated ethylenic linkage. The environment of the hydroxylic functions and one carboxyl group has been shown t o be as in (XI).Of the known triterpenoids of undetermined constitution remaining, senegenin has a claim to outstanding interest. Investigations directed to a study of the saponin of Polygala senega have spread over many years, but, as mentioned by Simonsen and Ross (I), such "investigations. . . have given rise to very divergent results". I t is this confusion, and its present clarification, which exculpates us from a charge of literary proiiferation in the presentation of incomplete work.Although senega extract has been used medicinally for some time, chiefly as a n expectorant (however, see ref.2 ) , the first results of chemical importance were obtained by Wedekind and Krecke (3). They isolated, by acid hydrolysis of the saponin, a product to which they assigned the formula C26H4406. I t contained two hydroxyl groups, as indicated by the formation of a diacetate, and gave a dimethyl ester.A more extensive study was later reported by Jacobs and Isler (4), who observed the presence of two crystalline sapogenins. T h a t of bwer solubility appeared to be senegenin, although the constants differed somewhat from those of Wedekind and Krecke: the diacetate, in particular, melted a t a much higher temperature. The empirical formula C30H4608 or C30H4408 was proposed, and evidence for an isolated ethylenic linkage found in a weak tetranitromethane test. Titration with alkali indicated the presence of two carboxyl groups (again confirmed by the preparation of a non-crystalline dimethyl ester) and the presence of a lactone was inferred by the consumption of a third equivalent of alkali on heating. Senegenin could not be recovered from the acidified hydrolysis mixture.The second sapogenin isolated from senega root by Jacobs and Isler was an acid, m.p. 257", which appeared to have the empirical formula C31H.5006 or C31H4806. This substance also gave a positive reaction with tetranitromethane, and was shown to give a diacetate. Hydrolysis revealed it to be the monoethyl ester of a dibasic acid. Both the sapogenins gave, on selenium dehydrogenation, the same substituted picene obtained previously from such triterpenoids as oleanolic acid, and shown to be ( 5 ) 1,8-dimethylpicene: results which strongly supported the supposition of Jacobs and Isler that they were dealing with a triterpenoid.

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“…The discovery of the first "carbonyl-assisted functionalization" by Lippman [1] in 1955, gestured the maturation of spectacular developments in functionalizing various unsaturated bonds, principally through intramolecular style. The well-studied reaction among them is the alkaline hydrolysis of esters and has a long history, [2] starting from their observation on substantial rate enhancement in the ester hydrolysis process enabled by a suitably positioned carbonyl group to the first observation of enzymatic hydrolysis by Balakrishnan in 1974.…”

Section: Emergence Of Carbonyl Group-assisted Functionalizationmentioning

confidence: 99%

“…The well-studied reaction among them is the alkaline hydrolysis of esters and has a long history, [2] starting from their observation on substantial rate enhancement in the ester hydrolysis process enabled by a suitably positioned carbonyl group to the first observation of enzymatic hydrolysis by Balakrishnan in 1974. [3] Later more detailed mechanistic studies by Newman [4] and Bender [5] demonstrated the idea of an intramolecular nucleophilic catalysis (Scheme 1), which involves intramolecular intercep-tion on the ester group by the monoanion of the derived hydrate (1). Besides these alkaline carbonyl ester hydrolysis, studies with other initiating nucleophiles [5b,6] such as cyanide, morpholine, and piperazine as well as heteroatom-based esters [7] (such as sulfonate and phosphate) have also been known.…”

Section: Emergence Of Carbonyl Group-assisted Functionalizationmentioning

confidence: 99%

“…In part due to these historical problems of developing a general protocol and based on their recent research success on carbonyl-assisted chemistry, [31] a synthetic protocol for 8-hydroxy-3-substituted isocoumarins 63 by the regioselective 6-endo-dig cyclization of 2,2-dimethyl-5-(alkynyl)-4H-benzo [d]-dioxin-4ones 62 has been established by Mohapatra et al in 2017. [43] This involves the use of 2,2-dimethyl-5-(alkynyl)-4H-benzo [d]- [1,3]dioxin-4-ones as the starting material and the best result for the cycloisomerization reaction was observed with PPh 3 AuCl in combination with AgSbF 6 in 1,4-dioxane as the solvent and water as one of the nucleophilic source (Scheme 21). Notably, only one regioisomeric product was formed even in lower catalyst loadings; 1 and 2 mol % of gold and silver catalysts were used, respectively.…”

Section: Carbonyl Participation Of 22-dimethyl Benzo [D]-[13]dioxinmentioning

confidence: 99%

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An Overview of Water‐Mediated Alkyne Functionalization by Neighboring Group Participation of Carbonyl Groups

Pradhan

Park

2020

Adv Synth Catal

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Reviewed herein, the progress employing the assistance of a neighboring carbonyl group for alkyne functionalization reactions that are mediated by water. Proper arrangement of these transformations is synthetically worthwhile because it will allow chemists to design straightforward synthetic routes for the construction of complex architectures with perfect regio-and chemoselectivity. Researchers must understand the mechanism before aiming a new idea based on these types of transformations as they proceed through a different way in comparison to the strategies that employ carbonyl groups as a directing group for CÀ H functionalization reactions. In general, an oxygen transposition event occurs in the presence of an alkyne activator. In an aim to expose the molecular diversity that can now be accessed employing intramolecular carbonyl assistance, all the precedents are organized systematically for the first time and can be expected to serve as a comprehensive reference work. Therefore, the key arrangement of this review is schemes accompanied by a concise explanatory text describing both advantages and limitations along with the mechanism. Different transformations are ordered in sections according to the chemical structure of the assisted groups. The overall objective of this review is to promote the application of carbonyl-assisted reactions beyond the methodologies dedicated to the regioselective synthesis of carbonyl derivatives and hence, serving it as a valuable reaction archetype in modern-day research for the synthesis of carbo-and heterocycles.

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Terpenoids. XIII.¹ The Structures of the Cactus Triterpenes Machaeric Acid and Machaerinic Acid²

Cited by 33 publications

References 0 publications

Chemical Interactions in the Cactus-Microorganism-Drosophila Model System of the Sonoran Desert1

Chemical Interactions in the Cactus-Microorganism-Drosophila Model System of the Sonoran Desert1

Terpenoids: V. Senegenin: Functional Groups and Part Structure

An Overview of Water‐Mediated Alkyne Functionalization by Neighboring Group Participation of Carbonyl Groups

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Terpenoids. XIII.1 The Structures of the Cactus Triterpenes Machaeric Acid and Machaerinic Acid2

Cited by 33 publications

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Chemical Interactions in the Cactus-Microorganism-Drosophila Model System of the Sonoran Desert1

Chemical Interactions in the Cactus-Microorganism-Drosophila Model System of the Sonoran Desert1

Terpenoids: V. Senegenin: Functional Groups and Part Structure

An Overview of Water‐Mediated Alkyne Functionalization by Neighboring Group Participation of Carbonyl Groups

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Terpenoids. XIII.¹ The Structures of the Cactus Triterpenes Machaeric Acid and Machaerinic Acid²