Iodine, a novel catalyst in carbohydrate reactions I. -isopropylidination of carbohydrates

Kartha, K. P. Ravindranathan

doi:10.1016/s0040-4039(00)84810-8

Cited by 141 publications

(50 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…3-Deoxy-C3-methylene-D-glucose (analog 1) and (E)-3-deoxy-C3-fluoromethylene-D-glucose (analog 2) were prepared as follows. Chromic oxidation (10) of the hydroxyl group at C3 of 1,2:5,6-diisopropylidene-a-D-glucose (11) gave the ketone 3. The Wittig reaction of ketone 3 with ylide prepared from triphenylmethylphosphonium bromide with potassium t-butanolate (12) or with the ylide derived from fluoromethyl triphenylphosphonium tetrafluoroborate (13) with n-butyllithium and potassium t-butanolate (14) gave, after quantitative acid hydrolysis (15) of the acetonides (16,17), the glucose analogs 1 § and 2$ (Scheme 1).…”

mentioning

confidence: 99%

X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

Carrell

Glusker

Burger

et al. 1989

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

192

138

View full text Add to dashboard Cite

The structures of crystalline D-xylose isomerase (D-xylose ketol-isomerase; EC 5.3.1.5) from Streptomyces rubiginosus and of its complexes with substrate and with an active-site-directed inhibitor have been determined by x-ray diffraction techniques and refined to 1.9-A resolution. This study identifies the active site, as well as two metal-binding sites. The metal ions are important in maintaining the structure of the active-site region and one of them binds C3-O and C5-O of the substrate forming a six-membered ring. This study has revealed a very close contact between histidine and Cl of a substrate, suggesting that this is the active-site base that abstracts a proton from substrate. The mechanism-based inhibitor is a substrate analog and is turned over by the enzyme to give a product that alkylates this same histidine, reinforcing our interpretation. The changes in structure of the native enzyme, the enzyme with bound substrate, and the alkylated enzyme indicate that the mechanism involves an "open-chain" conformation of substrate and that the intermediate in the isomerization reaction is probably a cis-ene diol because the active-site histidine is correctly placed to abstract a proton from C' or C2 of the substrate. A water molecule binds to C'O and C20 of the substrate and so may act as a proton donor or acceptor in the enolization of a ring-opened substrate. We (at the University of Strasbourg, V.B., F.M., D.T., and J.F.B.) designed and synthesized a substrate analog that is a suicide inactivator, analog 2 (Scheme 1) (9). It was used to test whether the D-xylose isomerase studied by x-ray diffraction techniques by us (at the Fox Chase Cancer Center, H.L.C. and J.P.G.) is active in crystalline state. Three crystal structures have been determined and each has been refined: native enzyme, enzyme with bound substrate/product, and MATERIALS AND METHODS Preparation of Active-Site-Directed Inhibitor. 3-Deoxy-C3-methylene-D-glucose (analog 1) and (E)-3-deoxy-C3-fluoromethylene-D-glucose (analog 2) were prepared as follows. Chromic oxidation (10) of the hydroxyl group at C3 of 1,2:5,6-diisopropylidene-a-D-glucose (11) gave the ketone 3. The Wittig reaction of ketone 3 with ylide prepared from triphenylmethylphosphonium bromide with potassium t-butanolate (12) or with the ylide derived from fluoromethyl triphenylphosphonium tetrafluoroborate (13) with n-butyllithium and potassium t-butanolate (14) gave, after quantitative acid hydrolysis (15) of the acetonides (16, 17), the glucose analogs 1 § and 2$ (Scheme 1). Anomers of analogs 1 and 2 were detected in aqueous solutions by NMR spectroscopy.Assay ofXylose Isomerase. The enzyme from S. rubiginosus was assayed by the cysteine-carbazole test (18) as the quantity of D-fructose formed. All reactions were performed in a 0.2 M sodium phosphate buffer (pH 8.0) at 40°C. The reaction mixture (1 ml) contained 0.8 M glucose, 0.01 M tTo whom reprint requests should be addressed. §In a total yield of 80%: m.p. 123-125. 13C-NMR (50 MHz, 2H20) 8 (ppm): 148; 146.4; 98.8; 9...

show abstract

mentioning

confidence: 99%

X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

Carrell

Glusker

Burger

et al. 1989

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

192

138

View full text Add to dashboard Cite

show abstract

“…We first studied the reactivity of anomeric alcohols to show the generality of the methodology. Thus, anomeric alcohol [16] 24, synthesized from -(+)-mannose, iodine, and acetone, was treated with benzoic acid, PPh 3 , NBS, and reagent 1 to form the correwww.eurjoc.org Table 1. Reaction of benzoic acid with various alcohols.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Thioesters by Simultaneous Activation of Carboxylic Acids and Alcohols Using PPh₃/NBS with Benzyltriethylammonium Tetrathiomolybdate as the Sulfur Transfer Reagent

2009

View full text Add to dashboard Cite

A new and simple route for the synthesis of thioesters starting from carboxylic acids and alcohols is reported by using tetrathiomolybdate as the key sulfur transfer reagent. Triphenylphosphane and N-bromosuccinimide were used for the activation of the carboxylic acid and alcohol in the same pot followed by the transfer of sulfur from tetrathiomolybdate. Thioesters were obtained in good to moderate yields. Pri-

show abstract

“…Elemental analyses were performed with a PerkinϪElmer 240 C instrument. (1a) was purchased from Aldrich, 3,4-O-isopropylidene--arabinopyranose (1b), [17] 2,3-Oisopropylidene--ribofuranose (1c), [18] 2,3,5-tri-O-benzyl--xylofuranose (1d), [19] 2,3,5-tri-O-benzyl--arabinofuranose (1e), [20] 2,3-Oisopropylidene--erythrose (1f) [21] and (2,3:5,6)-di-O-isopropylidene--mannofuranose (1g) [22] were prepared according to published procedures.…”

Section: Methodsmentioning

confidence: 99%

Preparation of N‐Glycosylhydroxylamines and Their Oxidation to Nitrones for the Enantioselective Synthesis of Isoxazolidines

et al. 2003

View full text Add to dashboard Cite

N‐benzyl‐ and N‐methyl‐N‐glycosylhydroxylamines 3a−i were conveniently obtained by reaction of sugars with N‐substituted hydroxylamines according to a novel procedure. Subsequent oxidation occurred at the alkyl group, selectively affording the corresponding C‐phenyl‐ and C‐unsubstituted N‐glycosylnitrones. C‐phenyl‐N‐glycosylnitrones 10 and 13 underwent highly stereoselective 1,3‐dipolar cycloaddition with dimethyl maleate, with the sugar moiety acting as a chiral auxiliary. Final removal of the glycosyl moiety afforded enantiopure enantiomeric isoxazolidines 17 and ent‐17 which are oxa‐analogues of proline diester derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

show abstract

Iodine, a novel catalyst in carbohydrate reactions I. -isopropylidination of carbohydrates

Cited by 141 publications

References 1 publication

X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

Synthesis of Thioesters by Simultaneous Activation of Carboxylic Acids and Alcohols Using PPh₃/NBS with Benzyltriethylammonium Tetrathiomolybdate as the Sulfur Transfer Reagent

Preparation of N‐Glycosylhydroxylamines and Their Oxidation to Nitrones for the Enantioselective Synthesis of Isoxazolidines

Contact Info

Product

Resources

About

Iodine, a novel catalyst in carbohydrate reactions I. -isopropylidination of carbohydrates

Cited by 141 publications

References 1 publication

X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.

Synthesis of Thioesters by Simultaneous Activation of Carboxylic Acids and Alcohols Using PPh3/NBS with Benzyltriethylammonium Tetrathiomolybdate as the Sulfur Transfer Reagent

Preparation of N‐Glycosylhydroxylamines and Their Oxidation to Nitrones for the Enantioselective Synthesis of Isoxazolidines

Contact Info

Product

Resources

About

Synthesis of Thioesters by Simultaneous Activation of Carboxylic Acids and Alcohols Using PPh₃/NBS with Benzyltriethylammonium Tetrathiomolybdate as the Sulfur Transfer Reagent