The asymmetric synthesis of .alpha.-amino acids. Electrophilic azidation of chiral imide enolates, a practical approach to the synthesis of (R)- and (S)-.alpha.-azido carboxylic acids

Evans, David A.; Britton, Thomas C.; Ellman, Jonathan A.; Dorow, Roberta L.

doi:10.1021/ja00166a045

Cited by 469 publications

(224 citation statements)

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“…This structural assignment was confirmed via an NMR-spectroscopic mixing experiment, whereby a small amount of synthetic m-tyrosine was added to the isolated active fraction (7). Finally, the absolute configuration of the isolated m-tyrosine was determined to be L by NMRspectroscopic comparison of its (S)-methoxytrifluoromethylphenylacetic acid [(S)-MTPA] derivative with the (R)-and (S)-MTPA derivatives of synthetic m-tyrosine (8). Structures of juglone, sorgoleone, the protein amino acid L-ptyrosine, and its isomer, L-m-tyrosine.…”

Section: Resultsmentioning

confidence: 93%

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Bertin

Weston²,

Huang

et al. 2007

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

172

185

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Fine fescue grasses displace neighboring plants by depositing large quantities of an aqueous phytotoxic root exudate in the soil rhizosphere. Via activity-guided fractionation, we have isolated and identified the nonprotein amino acid m-tyrosine as the major active component. m-Tyrosine is significantly more phytotoxic than its structural isomers o-and p-tyrosine. We show that mtyrosine exposure results in growth inhibition for a wide range of plant species and propose that the release of this nonprotein amino acid interferes with root development of competing plants. Acid hydrolysis of total root protein from Arabidopsis thaliana showed incorporation of m-tyrosine, suggesting this as a possible mechanism of phytotoxicity. m-Tyrosine inhibition of A. thaliana root growth is counteracted by exogenous addition of protein amino acids, with phenylalanine having the most significant effect. The discovery of m-tyrosine, as well as a further understanding of its mode(s) of action, could lead to the development of biorational approaches to weed control.allelopathy ͉ festuca ͉ rhizosphere ͉ root ecology ͉ Arabidopsis R oot exudation of small molecules plays a major role in plant ecosystems and is often associated with the development of competitive advantage through allelopathy (1, 2). Juglone, a highly phytotoxic naphthoquinone produced by black walnut (Juglans nigra L.), and sorgoleone, a substituted quinone from sorghum (Sorghum spp.), are two classic examples of potently active allelochemicals deposited via the plant's living root system ( Fig. 1) (3). Elucidation of the structures and mode of action of previously unknown root-derived phytotoxins could lead to new biorational approaches to weed control.Because of their stress tolerance and disease resistance, fescue (Festuca spp.) grasses are commonly used in landscape, roadside, and pasture settings, as well as for conservation purposes (4, 5). The unusual ability of many fine leaf fescue species to outcompete other plants is well known, and previous investigations suggested that fescue root exudates have phytotoxic properties (4). Here, we report the isolation, identification, and biological activity of m-tyrosine, a potent, structurally unusual broadspectrum phytotoxin exuded by the roots of some fine leaf fescue grasses. Results and DiscussionIn an initial field evaluation of 80 fine fescue cultivars, 8 cultivars with strong weed suppressive potential were identified and their allelopathic potential in laboratory settings was confirmed (4). Based on both field and laboratory results, we selected ''Intrigue,'' a common Chewing's fescue cultivar (Festuca rubra L. ssp. commutata), for further studies.To identify the allelopathic compound(s) contained in Intrigue root exudates, we developed an activity-guided separation scheme based on the inhibition of lettuce (Lactuca sativa L.) radicle elongation in a filter paper-based assay. By using this assay, we compared the phytotoxicity of root surface washes (hexanes, dichloromethane, methanol, and water) prepared from 2-w...

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Section: Resultsmentioning

confidence: 93%

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Bertin

Weston²,

Huang

et al. 2007

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

172

185

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“…32,33) Acidic hydrolysis of the dimethyl acetal moieties in 12a-f produced aldehydes 13a-f. The retro-Michael reaction of 13a-f using cesium carbonate (Cs 2 CO 3 ) as a base and subsequent treatments of the resulting cesium thiolates with propionyl or acetyl chloride, provided a-acylthio esters 14a-f or 15a-f.…”

Section: ) Based On These Preliminary Results (S)-4-benzyloxazolidmentioning

confidence: 99%

Synthesis and Biological Activity of Enantiomeric Pairs of 5-(Alk-2-enyl)thiolactomycin and 5-[(E)-Cycloalk-2-enylidenemethyl]thiolactomycin Congeners

Ohata¹,

Terashima

2009

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…With the exception of the more promising compounds cited above (9,27,30), N-methoxy-o-benzenedisulfonimide was prepared by reaction with diazomethane but without synthetic developments, whilst other derivatives could not be prepared.…”

Section: N-dialkylcarbamoyl-o-benzenedisulfonimides (32)mentioning

confidence: 99%

“…Although inactivated aromatic compounds were efficiently halogenated by using N-chloroand N-bromo-o-benzenedisulfonimide (27) In the diastereoselective fluorination of chiral imide enolates, Davis and co-workers used Evans' oxazolidinones (55) [29] as chiral auxiliaries to prepare the α-fluoroacids 57 and the β- …”

Section: N-fluoro-o-benzenedisulfonimide (30)mentioning

confidence: 99%

o-Benzenedisulfonimide: An Organic Reagent and Organocatalyst of Renewed Interest

Barbero¹,

Bazzi

Cadamuro

et al. 2011

COC

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ABSTRACT:Synthesized nearly one century ago as a saccharine-like sweetener compound, the obenzenedisulfonimide has received a discontinuous attention in the past. In the last century, various synthetic procedures have been reported, in confirmation of the interest in this intriguing compound. In recent years, it has been used as a leaving group in reactions of nucleophilic substitution of amines with alcohols or phenols to give the corresponding ethers. Its Nfluoroderivative is a stable and efficient fluorinating agent, which has found applications in several asymmetric syntheses. In previous studies, its conjugated base has been extensively used as stabilizing counter-ion of arenediazonium salts; safely isolated and stored in a dry state, ready to use, they have been applied successfully in many dediazoniation reactions, with interesting mechanistic insights. More recently, due to its high acidity, the o-benzenedisulfonimide has been used in catalytic amounts in some common acid-catalyzed organic reactions. Valuable aspects of this catalyst are its easy recovery from the reaction mixture and its reuse in other reactions, with clear economic and ecological advantages. Finally, the disulfonimide functional group has been proposed as a powerful chiral motif for strong Brønsted acids in asymmetric organocatalysis.

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The asymmetric synthesis of .alpha.-amino acids. Electrophilic azidation of chiral imide enolates, a practical approach to the synthesis of (R)- and (S)-.alpha.-azido carboxylic acids

Cited by 469 publications

References 0 publications

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Grass roots chemistry: meta -Tyrosine, an herbicidal nonprotein amino acid

Synthesis and Biological Activity of Enantiomeric Pairs of 5-(Alk-2-enyl)thiolactomycin and 5-[(E)-Cycloalk-2-enylidenemethyl]thiolactomycin Congeners

o-Benzenedisulfonimide: An Organic Reagent and Organocatalyst of Renewed Interest

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