Chiral Silylation Reagents for the Determination of Absolute Configuration by NMR Spectroscopy

Weibel, Douglas B.; Walker, Tameka R.; Schroeder, Frank C.; Meinwald, Jerrold

doi:10.1021/ol006162h

Cited by 22 publications

(13 citation statements)

References 5 publications

(5 reference statements)

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“…3) and pinoresinol in a ratio of Ϸ96:4. For the determination of the absolute configuration of the pinoresinol, we used our recently introduced chiral silylation reagents, which showed the caterpillars' compound to be (Ϫ)-pinoresinol of 94% enantiomeric purity (13,14).…”

Section: Resultsmentioning

confidence: 99%

“…The residue was dissolved in 0.6 ml of CD 3 OD, followed by acquisition of 1 H-NMR and ( 1 H, 1 H)-dqf-COSY spectra. The remaining 1.0 g of material was placed in a mixture of 10 ml of dioxane and 70 ml of 0.15 molar aqueous sulfuric acid (14). The mixture was stirred for 70 min at 65°C under argon and, after cooling to room temperature, was extracted with two 50-ml portions of a 1:1 mixture of ether and hexane.…”

Section: Methodsmentioning

confidence: 99%

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Pinoresinol: A lignol of plant origin serving for defense in a caterpillar

Schroeder

Campo

Grant

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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Pinoresinol, a lignan of wide distribution in plants, is found to occur as a minor component in the defensive secretion produced by glandular hairs of caterpillars of the cabbage butterfly, Pieris rapae. The compound or a derivative is appropriated by the larva from its normal food plant (the cabbage, Brassica oleracea). Pinoresinol was shown to be absent from the secretion if the larva was given a cabbage-free diet but present in the effluent if that diet was supplemented with pinoresinol. Pinoresinol is shown to be a feeding deterrent to ants (Formica exsectoides), indicating that it can complement the defensive action of the primary components of the secretion, a set of previously reported lipids called mayolenes. In the test with F. exsectoides, pinoresinol proved to be more potent than concomitantly tested mayolene-16.ignans comprise a large class of secondary metabolites in vascular plants. Derived from the three phenyl-propanoid precursors, p-coumaryl alcohol (1 in Fig. 1), coniferyl alcohol (2 in Fig. 1) and sinapyl alcohol (3 in Fig. 1), they fulfill important physiological functions in plants (1) and are of considerable pharmaceutical interest (2). For example, podophyllotoxin (4 in Fig. 1) derivatives are used extensively in anticancer treatments and have been shown recently to possess antiviral properties as well (3). Pinoresinol (5 in Fig. 1) is one of the structurally simplest lignans, being a dimer of coniferyl alcohol, and its frequent presence in woody or fibrous plants should come as no surprise [the Beilstein database (MDL Information Systems, San Leandro, CA) revealed 46 and 8 references, respectively, for the isolation of (ϩ)-pinoresinol and (Ϫ)-pinoresinol from plants] (4). Virtually any plant capable of producing lignin can be presumed to have the enzymes necessary to link two units of coniferyl alcohol (2 in Fig. 1) in a fashion leading to the bicyclic ring core of pinoresinol (5 in Fig. 1).The amount of pinoresinol produced by plants varies widely. Particularly high concentrations of pinoresinol have been found in young foliage, for example of Forsythia spp., as well as in the reproductive organs and seeds of many plants (5). The compound is therefore generally presumed to be a defensive agent, as is suggested also by its antihelminthic and antifungal activity (6-9). Animals are not known to produce pinoresinol or other dimeric lignols, nor have they been shown to acquire such compounds from plants. We here report the presence of pinoresinol in the defensive secretion of a caterpillar, the larva of Pieris rapae, the cabbage butterfly, one of the world's most familiar lepidopterans (10). We had earlier reported on the composition of this secretion, produced as droplets by glandular hairs on the back and flanks of the larva (11) (Fig. 2). We had noted the fluid to contain a series of structurally labile linolenic acid derivatives, the mayolenes (6 in Fig. 3), which we demonstrated to be protective against ants (Crematogaster lineolata) (11). We have found pinoresinol itself to also be dete...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Pinoresinol: A lignol of plant origin serving for defense in a caterpillar

Schroeder

Campo

Grant

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…Similarly, the AC of alcohols could be assigned on the basis of shifts in the 1 H NMR spectrum when derivatized with chloromenthoxydiphenylsilanes into silyl ethers. 22 The silyl reagent was particularly suitable for allylic alcohols that are incompatible with ester-based methodologies and its utility was demonstrated with several natural products.…”

Section: Chiral Reagents For Determining Ee and Acmentioning

confidence: 99%

Chiral Reagents for the Determination of Enantiomeric Excess and Absolute Configuration Using NMR Spectroscopy

Wenzel

Wilcox

2003

ChemInform

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Recent advances in the development of chiral derivatizing and solvating agents that facilitate the determination of enantiomeric excess and absolute configuration are reviewed. These include metal-containing species, host-guest systems, donoracceptor compounds, and liquid crystal discriminating agents. In the aggregate, these reagents can be used to analyze a wide range of compound classes. Chirality 15: 256-270, 2003.

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“…[198][199][200][201][202][203] These and structurally-related acids as well as several types of optically-active alcohols have found great utility to determine the absolute stereochemistry of enantiomerically pure or enriched secondary alcohols [353][354][355][356][357][358] and diols, 359,360 b-chiral alcohols, 361,362 a-chiral amines, [363][364][365][366][367] mixed chiral amines and alcohols, 368,369 chiral carboxylic acids, [370][371][372] and chiral 3-hydroxy b-lactams. 373 These reagents have also found combined utility in enantiomeric separation, including LC-NMR, plus determination of absolute stereochemistry of various types of compounds such as diastereomeric alcohols [374][375][376][377] and 2-hydroxypyrrolizidinones.…”

Section: Current Toolbox-nmr Approachesmentioning

confidence: 99%

Enantiomeric separation and determination of absolute stereochemistry of asymmetric molecules in drug discovery—Building chiral technology toolboxes

McConnell¹,

Bach

Balibar³

et al. 2007

Chirality

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The application of Chiral Technology, or the (extensive) use of techniques or tools for the determination of absolute stereochemistry and the enantiomeric or chiral separation of racemic small molecule potential lead compounds, has been critical to successfully discovering and developing chiral drugs in the pharmaceutical industry. This has been due to the rapid increase over the past 10-15 years in potential drug candidates containing one or more asymmetric centers. Based on the experiences of one pharmaceutical company, a summary of the establishment of a Chiral Technology toolbox, including the implementation of known tools as well as the design, development, and implementation of new Chiral Technology tools, is provided.

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Chiral Silylation Reagents for the Determination of Absolute Configuration by NMR Spectroscopy

Cited by 22 publications

References 5 publications

Pinoresinol: A lignol of plant origin serving for defense in a caterpillar

Pinoresinol: A lignol of plant origin serving for defense in a caterpillar

Chiral Reagents for the Determination of Enantiomeric Excess and Absolute Configuration Using NMR Spectroscopy

Enantiomeric separation and determination of absolute stereochemistry of asymmetric molecules in drug discovery—Building chiral technology toolboxes

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