New Factors Governing Stereoselectivity in Borohydride Reductions ofβ-D-Glycoside-2-uloses − The Peculiar Effect of “Activated” DMSO

Kerékgyártó, János; Rákó, János; Ágoston, Károly; Gyémánt, Gyöngyi; Szurmai, Zoltán

doi:10.1002/1099-0690(200012)2000:23<3931::aid-ejoc3931>3.0.co;2-w

Cited by 11 publications

(4 citation statements)

References 19 publications

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“…The carbohydrate oxiranes often produce a mixture of regioisomers depending on several factors . On the other hand, it is not clear from the available literature whether the reduction of C-2 alkylidene glycosides is influenced by the 3-OH protecting group lowering the stereoselectivity of these reactions as is known for 2-keto sugars . It is therefore obvious that there is a great need for new and general methodologies for the stereocontrolled construction of carbon−carbon bonds in carbohydrates.…”

mentioning

confidence: 99%

Anomeric Configuration-Directed Diastereoselective C−C Bond Formation in Vinyl Sulfone-Modified Carbohydrates: A General Route to Branched-Chain Sugars

et al. 2003

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[structure: see text] This is the first report on the diastereoselective addition of carbon nucleophiles to vinyl sulfone-modified hex-2-enopyranosides and pent-2-enofuranosides. Nucleophiles add to the C-2 position from a direction opposite to that of the disposition of the anomeric methoxy group. This novel concept of anomeric configuration-directed stereocontrolled carbon-carbon bond formation in vinyl sulfone-modified carbohydrates is general in nature and has been implemented in the synthesis of new hexopyranosyl and pentofuranosyl branched-chain sugars and densely functionalized carbohydrates.

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confidence: 99%

Anomeric Configuration-Directed Diastereoselective C−C Bond Formation in Vinyl Sulfone-Modified Carbohydrates: A General Route to Branched-Chain Sugars

et al. 2003

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“…[25][26][27] Next, ring-closing metathesis with the 2nd generation Hoveyda-Grubbs catalyst gave 1,2-annulated alkene 7. To evade silica-induced elimination, crude 2b was directly subjected to the manno-selective vinylation.…”

Section: Resultsmentioning

confidence: 99%

“…In general, α-ulosides are usually transformed into the corresponding glucosides, whereas -ulosides result in the formation of products with manno configuration. [25][26][27] Next, ring-closing metathesis with the 2nd generation Hoveyda-Grubbs catalyst gave 1,2-annulated alkene 7. The structure of 7 was confirmed by using H,H-NOESY NMR spectroscopy.…”

Section: Resultsmentioning

confidence: 99%

1,2‐Annulated Sugars: Synthesis of Polyhydroxylated 2,10‐Dioxadecalins with β‐manno Configuration

2016

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A new synthetic route to 1,2‐pyran‐annulated O‐glycosides (pyranopyrans) with β‐manno configuration is presented. Starting from a benzyl‐protected allyl β‐2‐uloside obtained by C2‐oxidation from the corresponding allyl glucoside, vinylation and ring‐closing metathesis provided a bicyclic alkene as a key substrate. Optimized reaction conditions involving the 2‐uloside were required to circumvent the formation of the unwanted 3,2‐enolone. Subsequent stereoselective alkene dihydroxylations were investigated and are presented. Diastereoselective catalytic osmoylation afforded the bicyclic β‐mannoside with syn‐diol configuration. In contrast, a sequence featuring a directed vanadium‐catalyzed alkene epoxidation and epoxide opening provided the corresponding 2,10‐dioxadecalin target compound with trans‐diol configuration. X‐ray crystallography was employed to study the molecular structure of the target compound with syn‐diol configuration. In addition, the molecular packing and hydrogen‐bonding interactions of the hydroxy‐rich molecule were examined.

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“…The attack of the nucleophile solely occurred from the equatorial side and no diastereomeric byproduct could be detected. Similarly, high stereoselectivities were previously observed for a wide variety of nucleophilic addition reactions to β-2-ulosides [5,[10][11][12]. In order to expand the synthetic applicability of the thus prepared branched mannosides we performed a series of transacetalizations affording products with variably orthogonally protected side chain formyl moieties.…”

Section: Resultsmentioning

confidence: 99%

2-C-Alkynyl and 2-C-cis-Alkenyl β-Mannosides with Acetal Protected γ-Aldehyde Functionality via 2-Uloside Alkynylation and Lindlar Hydrogenation

Borowski

Menzel

Ziegler

2016

Molbank

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Abstract:Benzyl 3,4,6-tri-O-benzyl-β-D-arabino-hexos-2-ulo-1,5-pyranoside was subjected to mannoselective ketone alkynylation with propiolaldehyde dibenzyl acetal, resulting in the formation of a 2-C-alkynyl β-mannoside bearing a γ-dibenzyl acetal functionality. Subsequent transacetalization of the acetal moiety with methanol and 1,3-dihydroxypropane and acetylation of position 2, respectively, gave 4 different 2-C-alkynyl branched mannosides. Lindlar hydrogenation of the latter under optimized conditions in dimethylformamide afforded a series of 2-C-cis-alkenyl mannosides. X-ray molecular structures of benzyl 3,4,6-tri-O-benzyl-β-D-arabino-hexos-2-ulo-1,5-pyranoside and of the branched glycoside benzyl 3,4,6-tri-O-benzyl-2-C-((Z)-3,3-dibenzyloxyprop-1-en-1-yl)-β-Dmannopyranoside are reported.

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New Factors Governing Stereoselectivity in Borohydride Reductions ofβ-D-Glycoside-2-uloses − The Peculiar Effect of “Activated” DMSO

Cited by 11 publications

References 19 publications

Anomeric Configuration-Directed Diastereoselective C−C Bond Formation in Vinyl Sulfone-Modified Carbohydrates: A General Route to Branched-Chain Sugars

Anomeric Configuration-Directed Diastereoselective C−C Bond Formation in Vinyl Sulfone-Modified Carbohydrates: A General Route to Branched-Chain Sugars

1,2‐Annulated Sugars: Synthesis of Polyhydroxylated 2,10‐Dioxadecalins with β‐manno Configuration

2-C-Alkynyl and 2-C-cis-Alkenyl β-Mannosides with Acetal Protected γ-Aldehyde Functionality via 2-Uloside Alkynylation and Lindlar Hydrogenation

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