A Concise and General Method for Doubly Attaching 2‐Ketosugars to Aglycon Diols: Synthesis of the Gomphosides and Spectinomycin

Lichtenthaler, Frieder W.; Cuny, Eckehard; Sakanaka, Osamu

doi:10.1002/ange.200500434

Cited by 10 publications

(4 citation statements)

References 31 publications

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“…by low-yield glycosylation of HMF with acetobromoglucose} 1. H and 13 C NMR data (CDCl 3 ) correlated well with those reported.…”

supporting

confidence: 89%

“…Optical rotations were measured on a Perkin-Elmer 241 polarimeter at 20°C using a cell of 1 dm path length; concentration (c) in g/100 mL and solvent are given in parantheses. 1 Melibiose monohydrate (5AEH 2 O, 10.5 g, 29 mmol) was added to a sodium aluminate solution, freshly prepared by gradual dissolution of aluminium granulate (3.5 g) in 30 mL of 20% aqueous NaOH (H 2 evolution), filtration after cessation of gas evolution, and addition of water to 35 mL. The mixture was then kept at 45°C for 4.5 h, whereby it had attained a red color and TLC indicated an approximate 90% conversion 39 (R f = 0.20 in nPrOH/water/EtOAc for educt, 0.31 for product).…”

Section: Generalmentioning

confidence: 97%

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Versatile building blocks from disaccharides: glycosylated 5-hydroxymethylfurfurals

Martin

Lichtenthaler

2006

Tetrahedron: Asymmetry

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“…by low-yield glycosylation of HMF with acetobromoglucose} 1. H and 13 C NMR data (CDCl 3 ) correlated well with those reported.…”

supporting

confidence: 89%

Section: Generalmentioning

confidence: 97%

Versatile building blocks from disaccharides: glycosylated 5-hydroxymethylfurfurals

Martin

Lichtenthaler

2006

Tetrahedron: Asymmetry

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“…This synthesis procedure involves the removal of the benzoyl oxy group at C-4ꞌ, generation of a carbonyl function at C-3ꞌ, and stereoselective reduction of the latter. The methodology for this reaction sequence was firstly developed by Lichtenthaler et al in the course of synthesizing bicyclic [14b] and tricyclic pyranodioxanes [15] as well as natural occurring gomphosides [17]. Reaction of the four steroidal glycosides 7a, 7b, 8a, and 8b with tetrabutylammonium acetate in anhydrous dichloromethane gave the corresponding benzoylated 3ꞌ-dehydrogomphoside analogues 9a, 9b, 10a, and 10b in good yields.…”

Section: Synthesesmentioning

confidence: 99%

“…Lichtenthaler et al developed a practical method for the bisacetalic annulation of 2-ketosugars to glycol [14], 1,2-cycohexane diols [15], cholestanediol [16], and gomphogenin, which led to the successful synthesis of the natural products (+)-gomphoside 1, (-)-3ꞌ-dehydrogomphoside 3a and (+)-3ꞌ-epi-gomphoside 3b [17].…”

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confidence: 99%

Synthesis of Analogues of (+)-Gomphoside, a Potent HIF-1 Inhibitor and Cardenolide

Cuny

2018

Natural Product Communications

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The milkweed bush Gomphocarpus fruticosus R.Br. found in Australia contains the steroidal glycoside (+)-gomphoside, its derivatives (-)-3ꞌdehydrogomphoside and (+)-3ꞌ-epi-gomphoside, as well as other glycoside compounds. The key structural features of these unique herbal agents are bislinked steroid to sugar linkages. (+)-Gomphoside is an extremely potent cardenolide and highly effective Hypoxia-Inducible Factor (HIF)-1 inhibitor. In addition, (+)gomphoside exhibits strong cytotoxicity on human breast cancer cell lines. The syntheses of (+)-gomphoside analogues with modified steroidal D rings are described here. The syntheses started with glycosylation of (+)-(2α,3β,5α)-2,3cholestanediol with benzoylated 2-keto sugar bromides, promoted by silver carbonate. Two regioisomeric glycosides with bent up and bent down ring anellation geometry were obtained, because of the two hydroxyl groups in the diol. Modification of the sugar ring of these glycosides by base-induced elimination of benzoic acid yielded (-)-3ꞌ-dehydrogomphoside analogues. The analogues of (+)-gomphoside and (+)-3ꞌ-epi-gomphoside were then obtained by stereoselective reduction of the 3ꞌ-carbonyl function. Compared to natural (+)-gomphoside, these analogues have the following unique structural features: a steroidal D ring with C 8 H 17-alkyl chain instead of an exocyclic butenolide moiety, a different configuration at bridgehead carbon-14, and lack of a hydroxyl group at this position. The resulting altered chemical properties make them interesting structures for pharmacological evaluation and they are potentially suitable candidates for the development of new inhibitors in cancer therapy.

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Synthesis of O,S‐Containing Polycycles via One‐Pot Michael Addition–Cycloacetalisation Cascade

2015

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An efficient diversity-oriented approach for the synthesis of previously unknownd i-, tri-, tetra-and spirocyclic pyrano-1,4-dioxinones,p yrano-1,4-dithiinonesa nd pyrano-1,4-oxathiinones from readily available starting compoundsh as been described. Cascade Michaela ddition-cycloacetalisation of acetoxy-, alkoxy-, and aryloxypyranones and 1,2dinucleophiles under mild Lewis acidic conditions providesadirect access to oxygen andsulfur-contain-ing complexh eterocycles.M echanistic aspects of the cascade process were elucidated in light of experimentalf acts.T he methodology described herein shows high promise for the synthesiso fs everal bioactive natural products as well as pharmaceutically important compounds.Pyranone esters 1a-1h and pyranone ethers 14a-14c employedi nt his study were synthesised according to literature Scheme 3. Diastereoselective synthesis of the ABCD-ring carbon skeleton of alliuocide G 7 and other analogousnatural products. [11a]Scheme 4. Large scale reactions to verify the scalability of the presentm ethod.

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A Concise and General Method for Doubly Attaching 2‐Ketosugars to Aglycon Diols: Synthesis of the Gomphosides and Spectinomycin

Cited by 10 publications

References 31 publications

Versatile building blocks from disaccharides: glycosylated 5-hydroxymethylfurfurals

Versatile building blocks from disaccharides: glycosylated 5-hydroxymethylfurfurals

Synthesis of Analogues of (+)-Gomphoside, a Potent HIF-1 Inhibitor and Cardenolide

Synthesis of O,S‐Containing Polycycles via One‐Pot Michael Addition–Cycloacetalisation Cascade

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