Desoxy‐nitrozucker. 3. Mitteilung. Synthese von Ketosen durch Kettenverlängerung von 1‐Desoxy‐1‐nitro‐aldosen. Nucleophile Additionen und Solvolyse von Nitroaethern

Aebischer, Bernard; Bieri, Jost H.; Prewo, Roland; Vasella, Andrea

doi:10.1002/hlca.19820650730

Cited by 81 publications

(20 citation statements)

References 26 publications

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“…are 'endo'-adducts. Assuming a pseudoequatorial position of the COOCH, group, examination of models shows that the coupling constants J(2,3), .J(2,3'), J (3,4), and J(3', 4) (see Table3) are only compatible with the proposed configurational assignment. The same coupling constants of 12a are only compatible with the 'endo'-adduct.…”

Section: 3-dipolar Addition Of Methylmentioning

confidence: 91%

“…However, this isomer was not detected in the mixture of cycloadducts. The configuration at C(3) of the 3-substituted 2-oxapyrrolizidines 13a, 13b, and 14a cannot be deduced from spectroscopic data, because the vicinal coupling constants J (3,4) are too similar to each other. The assignment is tentative and may be reversed.…”

Section: 3-dipolar Addition Of Methylmentioning

confidence: 96%

“…To a cooled soln. (-75", C02/i-PrOH) of 3 (3.038 g, 9.67 mmol) [3] in dry Et20 (40 ml), a soln. of DIBAH 20 H (10.5 ml, 12.6 mmol) was added through a syringe within 5 min.…”

Section: Experimental Partmentioning

confidence: 99%

“…For its preparation, the spirolactone 3 [3] (Scheme 2) was first reduced with diisobutylaluminium hydride (DIBAH) to give a crystalline hemiacetal4 (88%). Treatment of 4 with excess hydroxylamine in MeOH at reflux gave rapidly and quantitatively the oximes 5 (see below).…”

mentioning

confidence: 99%

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Diastereoselectivity in the Reaction of N‐Glycosyl‐nitrones: 1,3‐Dipolar Cycloaddition and Addition of Phosphite Anion

Bernet

Krawczyk

Vasella

1985

Helvetica Chimica Acta

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The direction of approach of dibenzyl phosphite on the one hand and of dipolarophiles on the other hand to the spironitrone 7 was examined. The nitrone 7 was prepared from the lactone 3. The nucleophilic addition of dibenzyl phosphite gave 8 as a single adduct (86%). Its structure was established by X-ray analysis. From the cycloaddition of methyl methacrylate, the products 9a, 9b, l l a , and l l b (83:2:7.5:7.5, 81 %) were isolated. The structure of the main adduct 9a was established by an X-ray analysis of a derivative of it, and the structures of the other adducts were deduced from their NMR spectra. The cycloaddition of 7 and methyl acrylate gave the adducts 10a, lob, 12a, 13a, 13b, and 14a (27:10:54:1:2:6,87%). The structures of these compounds were deduced from their NMR spectra. The results are discussed in relation to prior hypothesis.1. Introduction. -The nucleophilic addition of dialkyl phosphite anions to (2)-Calkyl-N-(2,3 : 5,6-di-0 -isopropylidene-cc -D-mannofuran0syl)nitrones 1 gives the (1 S ) -Nglycosyl-N-hydroxyaminophosphonates 2 with a diastereoselectivity of about 90 % [ 11 (Scheme I ) . A high diastereoselectivity had been predicted, based on the analogy between a LUMO-controlled 1,3-dipolar cycloaddition of N-glycosyl-nitrones and the addition of nucleophiles to it [ 11.

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Section: 3-dipolar Addition Of Methylmentioning

confidence: 91%

Section: 3-dipolar Addition Of Methylmentioning

confidence: 96%

“…To a cooled soln. (-75", C02/i-PrOH) of 3 (3.038 g, 9.67 mmol) [3] in dry Et20 (40 ml), a soln. of DIBAH 20 H (10.5 ml, 12.6 mmol) was added through a syringe within 5 min.…”

Section: Experimental Partmentioning

confidence: 99%

mentioning

confidence: 99%

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Diastereoselectivity in the Reaction of N‐Glycosyl‐nitrones: 1,3‐Dipolar Cycloaddition and Addition of Phosphite Anion

Bernet

Krawczyk

Vasella

1985

Helvetica Chimica Acta

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“…2) reagierte mit p-Nitrobenzaldehyd zum gelben, einheitlichen, aber wenig stabilen Nitron 18 der P-D-Galactofuranose, dessen Struktur aus seiner ozonolytischen Umwandlung in die kristalline Nitro-b-D-galactofuranose 19 (52% aus 7) folgt. Die Oxime 8 [18] und 9 [19] 26)) mit denjenigen der fruher hergestellten Nitromannopyranosen (l/2 und 27/28 [9] [13]; s. Tub.…”

Section: ' )unclassified

Desoxy‐nitrozucker. 13. Mitteilung. Herstellung ungeschützter und partiell geschützter 1‐Desoxy‐1‐nitro‐D‐aldosen sowie Röntgenstrukturanalysen einiger ihrer Vertreter

Beer

Bieri

Macher

et al. 1986

Helvetica Chimica Acta

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, and 4,6-0-benzylidene-~-~-galactose (see 42) were prepared by ozonolysis of the corresponding nitrones which were obtained from the acid-catalyzed reaction of p-nitrobenzaldehyde with the hydroxylamine 4, the unprotected oximes 3 and 5-9 and the 4,643 -benzylidenc oximes 3537, respectively (Schemes 1-3). Thegluco-and manno-nitrones 10 and 12 were isolated, and their ring size and their anomeric and ( E / Z ) configurations were determined by NMR spectroscopy and by their transformation into their corresponding nitro derivatives. The structure of the deoxynitroaldoses were determined by NMR spectroscopy, polarimetry, and, in the case of 14, 16, and 17, by formation of the 4,6-O-benzylidene (14+40) or 4,6-0-isopropylidene (16+43, 17-23) derivatives (Scheme 3). Acetylation of the nitroglucopyranose 14, the 2-acetamido-nitroglucopyranose 17, and the nitrogalactofuranose 19 gave the crystalline peracetylated nitroaldoses 22, 24, and 45, respectively (Scheme 4 , Figs. I and 3); acetylation of the nitromannopyranose 16 gave the nitro-arabino-glycal44 (Scheme 4 ) . The structure of the peracetylated nitroglucopyranose 22, the nitroglucosamine 25, the nitrogalactofuranose 45, and the nitroribofuranose 20 were confirmed by X-ray analysis (Figs. 1 4 ) . In all cases, including the b-u-glucopyranose derivative 22, considerably shortening of the (endocyclic) C( 1)-0 bond was observed. Basecatalyzed anomerization of the 8-D-configurated nitroglucopyranose 14, the nitromannopyranose 16, the benzylidene acetal 40 of nitroglucose, and the 2,3,4,6-tetraacetylated glucosamine derivative 24 gave the corresponding nitro-cc-u-aldoses 15, 26,47, and 25, respectively (Scheme 4).

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A Ramberg−Bäcklund Approach to the Synthesis ofC-Glycosides,C-Linked Disaccharides, andC-Glycosyl Amino Acids

et al. 2002

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Synthetic applications of exo-glycals, derived from S-glycoside dioxides using the Meyers variant of the Ramberg−Bäcklund rearrangement, are described. These include a formal synthesis of a β-glycosidase inhibitor 12 and an efficient route to spirocyclic glucose derivatives 17 and [a] Scheme 2. exo-Glycals are versatile intermediates for the synthesis of more highly functionalised C-glycosides CHCl 3 )}. Sigmatropic rearrangements involving the enol ether function have recently been described: a Claisen rearrangement of 6-vinyl exo-glycals [12] and a ClaisenϪIreland rearrangement of 2-O-acyl exo-glycals [13] furnish cyclooctene and C-glycan derivatives, respectively. Exomethylenic sugars have also proved to be good substrates for ring-closing olefin metathesis: derivatives of 2a bearing an unsaturated side chain at position 2 have been shown to undergo ruthenium catalysed ring closure to give bicyclic glycosylidene compounds. [14] Postema and Calimente have also exploited this powerful carbonϪcarbon bond-forming process for the preparation of C1-substituted glycals [15a] and C-linked disaccharides. [15b] The phenyl-substituted exo-glycal derivative 2b is accessible in high yield and good stereoselectivity from the tandem halogenation-RambergϪBäcklund rearrangement of benzyl sulfone 1b (Scheme 1). We decided to explore the elaboration of this substrate (Scheme 3). When hydroboScheme 3. HydroborationϪoxidation of exo-glycal 2b to give the known C-glycoside 11Eur.

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Desoxy‐nitrozucker. 3. Mitteilung. Synthese von Ketosen durch Kettenverlängerung von 1‐Desoxy‐1‐nitro‐aldosen. Nucleophile Additionen und Solvolyse von Nitroaethern

Cited by 81 publications

References 26 publications

Diastereoselectivity in the Reaction of N‐Glycosyl‐nitrones: 1,3‐Dipolar Cycloaddition and Addition of Phosphite Anion

Diastereoselectivity in the Reaction of N‐Glycosyl‐nitrones: 1,3‐Dipolar Cycloaddition and Addition of Phosphite Anion

Desoxy‐nitrozucker. 13. Mitteilung. Herstellung ungeschützter und partiell geschützter 1‐Desoxy‐1‐nitro‐D‐aldosen sowie Röntgenstrukturanalysen einiger ihrer Vertreter

A Ramberg−Bäcklund Approach to the Synthesis ofC-Glycosides,C-Linked Disaccharides, andC-Glycosyl Amino Acids

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