A highly convergent and effective synthesis of the phytoalexin elicitor hexasaccharide

Wang, Wei; Kong, Fanzuo

doi:10.1016/s0008-6215(99)00003-8

Cited by 12 publications

(1 citation statement)

References 27 publications

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“…The de novo chemical synthesis of the oligosaccharide elicitor (7-9) is a rapidly developing field; however, this mainly serves the investigation of structure-activity relationships and has not been of practical use. We have reported a highly regioand stereoselective method to prepare the glucohexatose elicitor through ortho ester formation-rearrangement (10,11). Substantial improvements have been made to this method to develop a new and efficient way to prepare the elicitor on a large scale (see Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Large-Scale Preparation of the Phytoalexin Elicitor Glucohexatose and Its Application as a Green Pesticide

Ning

Kong

BangMao

et al. 2003

J. Agric. Food Chem.

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Large-scale preparation of the phytoalexin elicitor was achieved through a highly regio-and sterereoselective synthesis using 2,3,4,6-tetra-O-benzoyl-D-glucopyranosyl trichloroacetimidate (1), 1,2:5,6-di-O-isopropylidene-R-D-glucofuranose (2), and 6-O-acetyl-2,3,4-tri-O-benzoyl-R-D-glucopyranosyl trichloroacetimidate (3) as the synthons. Coupling of 1 with 2 gave the 1f3-linked disaccharide; subsequent selective removal of 5,6-O-isopropylidene to give 5 followed by selective 6-O-glycosylation with 1 afforded the trisaccharide 6. Hydrolysis to remove the 1,2-O-isopropylidene was accompanied by ring expansion, giving 3,6-branched pyranosyl trisaccharide. Acetylation, selective 1-O-deacetylation, and activation with trichloroacetonitrile gave the trisaccharide donor 7. The trisaccharide acceptor 9 was prepared from condensation of the disaccharide 5 with 3 and subsequent 6-O-deacetylation. Coupling of the trisaccharide donor 7 with the trisaccharide acceptor 9 and subsequent deprotection afforded the glucohexatose elicitor. The cost of the produced glucohexatose should be low enough to allow its applications in agriculture as a green pesticide. At a concentration of 5-10 mg/L, the resultant elicitor was used to treat growing orange trees and harvested oranges, giving very encouraging results, comparable with those obtained using commercial pesticides at a concentration of 1400 mg/L (Topsin-M) for growing trees and 900 mg/L (Tecto) for harvested oranges, respectively. Treatment of tomato leaves against Botrytis cinerea with the synthetic elicitor at a concentration of 10 mg/L gave 82% inhibition, comparable with the inhibition of 84% by Wanmeiling at a concentration of 1000 mg/L. Treatment of tea leaves also showed promising results.

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Section: Resultsmentioning

confidence: 99%

Large-Scale Preparation of the Phytoalexin Elicitor Glucohexatose and Its Application as a Green Pesticide

Ning

Kong

BangMao

et al. 2003

J. Agric. Food Chem.

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Zemplén Deacetylation

2010

Comprehensive Organic Name Reactions and Reagents

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The efficient removal of the O ‐acetyl protecting groups of carbohydrates by treatment of the O ‐acetylated substrates in methanol with a catalytic amount of sodium methoxide at room temperature is generally known as the Zemplén deacetylation, Zemplén de‐ O ‐acetylation, or Zemplen deacetylation. In addition, after the reaction, the O ‐acetyl‐protected carbohydrates are transformed into unprotected ones, in a manner analogous to the hydrolysis of an ester, thus this reaction is termed as the Zemplen saponification as well. However, it has been reported that the Zemplén deacetylation is probably not suitable for the deprotection of carbohydrates with disulfide linkages. This reaction has wide applications in carbohydrate chemistry.

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Other Methods of Glycosylation

Panza

Lay

2000

Carbohydrates in Chemistry and Biology

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A highly convergent and effective synthesis of the phytoalexin elicitor hexasaccharide

Abstract: The peracetylated hexasaccharide 1,2,4-tri-O-acetyl-3-O-(2,3,4,6-tetra-O-acetyl-b-D-glucopyranosyl)-6-O- (2,3,4-tri-O-acetyl-6-O-(2,4-di-O-acetyl-3,6-di-O-(2,3,4,6-tetra-O-acetyl-b

Cited by 12 publications

References 27 publications

Large-Scale Preparation of the Phytoalexin Elicitor Glucohexatose and Its Application as a Green Pesticide

Large-Scale Preparation of the Phytoalexin Elicitor Glucohexatose and Its Application as a Green Pesticide

Zemplén Deacetylation

Other Methods of Glycosylation

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