Sugar β-ketoesters: new chirons in the synthesis of 6-deoxyheptulosurono-7,4-lactones

Dhavale, Dilip D.; Bhujbal, Namdeo N.; Joshi, Pallavi; Desai, Sandhya G.

doi:10.1016/0008-6215(94)00166-9

Cited by 16 publications

(16 citation statements)

References 14 publications

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“…Our previous report describes a synthesis of sugar β-keto ester 3 by the reaction of 1,2- O -isopropylidene-3- O -benzyl-α- d - xylo -pentodialdose ( 2 ) with ethyl diazoacetate in the presence of BF 3 −OEt 2 . Decarbalkoxylation of 3 using sodium chloride in wet DMSO afforded 5-keto sugar 4 in good yield (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

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A Stereoselective Synthesis of 1,6-Dideoxynojirimycin by Double-Reductive Amination of Dicarbonyl Sugar

1997

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Section: Resultsmentioning

confidence: 99%

“…All the solvents, n -hexane, THF, diethyl ether, chloroform, methanol, petroleum ether (60−80 °C), and ethyl acetate, were purified and dried before use. Ethyl 3- O -benzyl-6-deoxy-1,2- O -isopropylidene-α- d - xylo -hepto-5-ulo-furanuronate (sugar β-keto ester) ( 3 ) was prepared from 2 in 85% yield as reported earlier …”

Section: Methodsmentioning

confidence: 99%

A Stereoselective Synthesis of 1,6-Dideoxynojirimycin by Double-Reductive Amination of Dicarbonyl Sugar

1997

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“…43 As shown in Scheme 1, treatment of 3a with 9:1 TFA-water at 0°C for 2 h, followed by removal of solvent under reduced pressure and column chromatography of the crude product afforded ethyl 4-O-benzyl-3,5-dihydroxy-6-oxocyclohex-1-ene carboxylate (4a) [Vasella et al 51 reported the synthesis of analogous cyclohexenone, namely tertbutyl 3,4,5-tri-O-triethylsilyl-6-oxo-cyclohex-1-ene carboxylate, from methyl 6-deoxy-6-iodo-a-D-glucopyranoside in 50% yield. However, further conversion to catechuate derivative is not reported.].…”

Section: Resultsmentioning

confidence: 97%

“…20,[40][41][42] While working in the area of carbohydrate chemistry, we have synthesized sugar b-ketoesters and demonstrated their utility in the synthesis of griseolic acid and nojirimycin analogues. [43][44][45][46][47][48][49] We now demonstrate the transformation of sugar b-ketoesters 3a/b to catechuic acid (1) and ethyl 2,4,5-trihydroxybenzoate (2) by emulating the biochemical cascade reactions (vide supra) of intramolecular aldol condensation and enolization that are known from poly-b-ketoesters to phenolic acids/esters. 50 Our results are reported herein.…”

Section: Introductionmentioning

confidence: 99%

Catechuic acid and ethyl 2,4,5-trihydroxybenzoate from d-glucose

Bhujbal

Bande

Dhavale

2009

Carbohydrate Research

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“…To our knowledge, only one unsuccessful report is available 8 wherein, the Wolff rearrangement of 3,4,5,6,7-penta-O-acetyl-1-deoxy-1-diazo-D-gluco-heptulose led to the formation of an unsaturated acid namely trans-4,5,6,7-tetra-O-acetyl-2,3-dideoxy-D-arabino-hept-2-enonic acid and not the expected saturated b-acetoxy acid. As a part of our continuing interest in the synthesis of biologically active compounds, 9 we have investigated the Wolff rearrangement of sugar derived α-diazo ketones 5a-d and our results are reported herein.…”

Section: Methodsmentioning

confidence: 99%

Synthesis of C1-C6 Segment of Carbonolide B: Wolff Rearrangement of Sugar α-Diazo Ketones

Tilekar¹,

Patil²,

Dhavale³

2000

Synthesis

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Silver benzoate catalysed Wolff rearrangement of a series of a-diazo ketones, derived from furanuronic acids, in methanol proceeds with good yields to produce the corresponding one carbon homologated methyl-5-deoxy-hexo-furanuronate. The utility of methyl-1,2-O-isopropylidene-3-O-methyl-5-deoxy-a-D-xylo-hexofuranuronate was demonstrated in the synthesis of the right wing segment of carbonolide B -the aglycone of the 16 membered macrolide antibiotic carbomycin B.Carbomycin B (magnamycin B), tylosin and josamycin (leucomycin A3) constitute the medicinally important 16-membered macrolide antibiotics. The structural aspects, intriguing configurational features, and potential biological properties of these macrolide antibiotics have been the subject of synthetic studies over the years. This has resulted in a number of carbohydrate, 1 as well as noncarbohydrate 2 based convergent syntheses of carbonolide B 1 (the aglycone portion of carbomycin B). Examination of the right hand portion of 1 shows the C1-C9 segment 2 which could be obtained by the Michael addition of lithium methallyl cuprate to the a,b-unsaturated ester 3 (Scheme 1). The key intermediate for the formation of 3 is methyl-a-D-xylo-hexo-furanuronate 4a (upon hydrolysis of 1,2-O-isopropylidene functionality followed by Wittig olefination) which represents the C1-C6 carbon framework of 1 and could be derived from D-glucose. The presence of three contiguous stereogenic centers from C3 to C5 with hydroxyl functionalities makes the carbohydrate route more appropriate for its synthesis. Only two chiron approaches for 4a are known so far. The first strategy reported by Nicolaou 3 involves the multi-step synthesis of 5,6-dideoxy-3-O-methyl-1,2-O-isopropylidene-a-D-xylo-hexo-5-eno-furanose from D-glucose followed by hydroboration and oxidative workup with H 2 O 2 /NaOH to give 5-deoxy-3-O-methyl-1,2-O-isopropylidene-a-Dxylo-hexo-furanose. Oxidation of the primary alcohol to the acid and esterification with diazomethane afforded 4a. While, in the second route 4 4a (along with its C4 epimer) was derived from the 5,6-dideoxy-6-flouro-6-(N-methyl-N-phenyl)-5,6-enamino-3-O-methyl-1,2-O-isopropylidene-a-D-xylo-hexo-furanose by reaction with 5% HCl in methanol. Although, the first route has wide utility, the second approach has very limited synthetic applications. It occurred to us that the Wolff rearrangement of sugar derived a-diazo ketone 5a in methanol should lead directly to 4a (free from its C4 epimer) (Scheme 1). The compound 5a in turn could be readily obtained from D-glucose. Scheme 1In recent years, the utility of a-diazocarbonyl derivatives either via carbene generation or through Wolff rearrangement has attracted considerable attention from both the synthetic and the mechanistic point of view. 5 The important synthetic application of the Wolff rearrangement is the Arndt−Eistert synthesis for one carbon homologation of carboxylic acids. 6 The fact that the rearrangement proceeds with the retention of configuration at the asymmetric carbon next to the carbonyl g...

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Sugar β-ketoesters: new chirons in the synthesis of 6-deoxyheptulosurono-7,4-lactones

Cited by 16 publications

References 14 publications

A Stereoselective Synthesis of 1,6-Dideoxynojirimycin by Double-Reductive Amination of Dicarbonyl Sugar

A Stereoselective Synthesis of 1,6-Dideoxynojirimycin by Double-Reductive Amination of Dicarbonyl Sugar

Catechuic acid and ethyl 2,4,5-trihydroxybenzoate from d-glucose

Synthesis of C1-C6 Segment of Carbonolide B: Wolff Rearrangement of Sugar α-Diazo Ketones

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