Reductive cleavage as a route to carbohydrate enolates. Applications to the synthesis of C-linked disaccharides

Binch, Hayley; Griffin, Andrew M.; Schwidetzky, Sabine; Ramsay, M. V. J.; Gallagher, Timothy; Lichtenthaler, Frieder W.

doi:10.1039/c39950000967

Cited by 26 publications

(20 citation statements)

References 18 publications

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“…Treatment of 1 with the diacetonegalactose-6-aldehyde 24, for example, smoothly gave an approximately 8:1 mixture of two addition products ( 1 H NMR), [23] which, because of difficulties in separating the mixture on silica gel, was directly subjected to NaHCO 3 treatment in aqueous acetone to induce β-elimination of benzoate. This resulted in the isolation of the beautifully crystalline galacto-dihydropyranone 25 (yield as high as 73%).…”

Section: Methodsmentioning

confidence: 99%

C‐Glycosidations of a 2‐Ketohexosyl Bromide with Electrophilic, Radical, and Nucleophilic Anomeric Carbons

Lichtenthaler¹,

Lergenmüller²,

Schwidetzky³

2003

Eur J Org Chem

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The susceptibility of acylated 2‐ketohexosyl halides to C‐homologation is demonstrated with the easily accessible tri‐O‐benzoyl‐α‐D‐arabino‐hexos‐ulosyl bromide 1 as the model compound. C‐Glycosidation with an electrophilic anomeric carbon requires prior carbonyl protection, to avoid carbonyl addition by the C‐nucleophile, for example, as the cyanohydrin. Silver triflate‐promoted reaction with the silylenol ether of acetophenone then efficiently yields the β‐phenacyl product. With thermal (AIBN) or photochemical induction, 1 smoothly generates an anomeric radical − comparatively electrophilic, due to its capto‐dative substitution − which exclusively traps hydrogen in the presence of tributyltin and electron‐deficient alkenes. With allyltributylstannanes, however, it reacts with high stereoselectivity to afford α‐C‐allyl glycosiduloses. The α‐bromoketone functionality in ulosyl bromide 1 is susceptible to Reformatsky conditions: treatment with zinc‐copper couple readily generates the 1,2‐enolate, a most simple anomeric nucleophile, which effectively adds to aldehydes to give α‐C‐hydroxyalkyl glycosiduloses or α‐C‐disaccharides (with sugar aldehydes) with a high degree of double stereoselection. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Section: Methodsmentioning

confidence: 99%

C‐Glycosidations of a 2‐Ketohexosyl Bromide with Electrophilic, Radical, and Nucleophilic Anomeric Carbons

Lichtenthaler¹,

Lergenmüller²,

Schwidetzky³

2003

Eur J Org Chem

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“…This may be advantageously used for regioselective enolate formation in polycarbonyl compounds, which is difficult to achieve by base-induced proton abstraction. [80][81][82] To extend the scope of the Reformatsky reaction, various parameters have been extensively investigated. Since the reaction is initiated by insertion of zinc into the carbon-halogen bond, most efforts have been focused on the activation of zinc or the utilization of other metals to facilitate the insertion.…”

Section: -76)mentioning

confidence: 99%

Investigation of Innovative Synthesis of Biologically Active Compounds on the Basis of Newly Developed Reactions

Honda

2012

CHEMICAL & PHARMACEUTICAL BULLETIN

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Synthesis of biologically active compounds, including natural products and pharmaceutical agents, is an important and interesting research area since the large structural diversity and complexity of bioactive compounds make them an important source of leads and scaffolds in drug discovery and development. Many structurally and also biologically interesting compounds, including marine natural products, have been isolated from nature and have also been prepared on the basis of a computational design for the purpose of developing medicinal chemistry. In order to obtain a wide variety of derivatives of biologically active compounds from the viewpoint of medicinal chemistry, it is essential to establish efficient synthetic procedures for desired targets. Newly developed reactions should also be used for efficient synthesis of desired compounds. Thus, recent progress in the synthesis of biologically active compounds by focusing on the development of new reactions is summarized in this review article.

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“…Aldol-type reactions, which are some of the most effective methods for forming C-C bonds, have also been investigated for the formation of a C-glycosidic linkage; in these cases, 1-deoxygluco-2-uloses or 2-ulosyl-l-bromides 54,55) were used as precursors for generating 1-enolates. [56][57][58] However, the yields of C-glycosides were insufficient, and problems remained; as shown in Chart 2, the former gave undesirable enolization at the 3-position of uloses to give 19, and in the latter case the precursors were significantly unstable. SmI 2 can reduce functional groups such as hydroxy, acetoxy, and alkoxy groups when a carbonyl group is present at the a-position of these functional groups, and the generation of samarium enolates as intermediates is presumed to occur during the reaction course.…”

Section: Synthesis Of Branched-sugar Nucleosides Bymentioning

confidence: 99%

“…Because of their unique and complex structures, considerable efforts have been devoted to the total synthesis, however, none of these attempts had been yet successful. [68][69][70][71][72][73][74][75] Having established the SmI 2 -promoted aldol reaction, we planned to synthesize herbicidin B by the aldol reaction between 1-phenylthio-2-urose derivative 32 and xyloadenosine-5Ј-aldehyde derivative 34 (Chart 5). Since this reaction proceeds under neutral condition, it was expected to be suitable for the use of the sensitive substrates such as 34.…”

Section: Total Synthesis Of Herbicidin Bmentioning

confidence: 99%

Fine Synthetic Nucleoside Chemistry Based on Nucleoside Natural Products Synthesis

Ichikawa

2008

CHEMICAL & PHARMACEUTICAL BULLETIN

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Synthetic nucleoside chemistry based on nucleoside natural products synthesis were described. First, a samarium diiodide (SmI 2 )-promoted aldol reaction with the use of a a-phenylthioketone as an enolate was developed. The characteristics of this reaction are that the enolate can be regioselectively generated and the aldol reaction proceeds under near neutral condition. This reaction is proved to be a powerful reaction for the synthesis of complex nucleoside natural products, and herbicidin B and fully protected tunicaminyluracil, which were undecose nucleoside natural products, were synthesized. Next, the synthetic methodology of the caprazamycins, which are promising antibacterial nucleoside natural products, was also developed by the strategy including b bselective ribosylation without using a neighboring group participation. Our synthetic route provided a range of key analogues with partial structures to define the pharmacophore. Simplification of the caprazamycins was further pursued to develop diketopiperazine analogs.

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Reductive cleavage as a route to carbohydrate enolates. Applications to the synthesis of C-linked disaccharides

Abstract: The carbohydrate-derived a-bromo ketones 4 and 5 undergo reductive cleavage using either Zn-Cu or CeC13-Nal and the resulting enolates are trapped by carbohydrate-based aldehydes 6, 7 and 14 t o give C-disaccharide derivatives.

Cited by 26 publications

References 18 publications

C‐Glycosidations of a 2‐Ketohexosyl Bromide with Electrophilic, Radical, and Nucleophilic Anomeric Carbons

C‐Glycosidations of a 2‐Ketohexosyl Bromide with Electrophilic, Radical, and Nucleophilic Anomeric Carbons

Investigation of Innovative Synthesis of Biologically Active Compounds on the Basis of Newly Developed Reactions

Fine Synthetic Nucleoside Chemistry Based on Nucleoside Natural Products Synthesis

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