Monosaccharide mit stickstoffhaltigem Ring, XII. Über Monosaccharide mit stickstoffhaltigem Siebenring

Paulsen, Hans; Todt, Klaus

doi:10.1002/cber.19671000217

Cited by 71 publications

(19 citation statements)

References 17 publications

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“…Le seul azolide a avoir CtC ttudie jusqu'h prtsent est l'acttyl-l pyrrole 14 dont la barriere a t t t dkterminte indtpendement par trois groupes d'auteurs (19-21) (tableau 3); la valeur trouvte, environ 52 kJ mol-I est beaucoup plus basse que celle des amides; par exemple pour I'acttyl-1 pyrrolidine 15 on trouve AG* = 75 kJ molpl (22). L'introduction d'un atome d'azote sp2 en position 3 diminue la barriere d'environ 10 kJ mol-l: comparer les produits 12 et 14.…”

Section: Rcsultats Et Discussionunclassified

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a-pentalène. XI. Etude par résonance magnétique nucléaire de l'imidazo [1,2-b] pyrazole et du pyrazolo [1,5-a] benzimidazole

Elguero¹,

Fruchier²,

Knutsson³

et al. 1974

Can. J. Chem.

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Chem. 52, 2744 (1974).L'Ctude r.m.n, a perinis de determiner la tautomerie annulaire et I'isoinCrie de position du derive acetyle de deux systemes hCttroaromatiques [5,5]: dans tous les cas c'est le praduit substitue (par H ou COCH,) sur l'atorne d'azote imidazolique qui est le plus stable. On a mis egalenient en evidence des couplages peu courants avec le NH dans les produits non substitues sur I'azote et des barrieres anormalement elevees dans les azolides, ce qui a conduit a eniettre I'hypothese d'une diminution de l'arornaticite de la partie imidazolique.Josi ELGUERO, ALAIN FRUCHIER, LEIF K N U T S S O~, R E N~ LAZARO, and JAI\ SA~DSTROM. Can. J. Chem. 52, 2744 (1974).Nuclear magnetic resonance spectroscopy has allowed us to determine the annular tautomerism in two [5,5]-heteroaromatic systems and the position of the acetyl group in their acetyl derivatives. In each case, the more stable compound is the one in which the imidazolic nitrogen atom is bearing H or COCH,. We have also found unusual couplings with the N-H in the N-unsubstituted conlpounds and abnormally high barriers for the azolides. These observations agree well with the hypothesis of a decrease in the aromaticity of the imidazolic part.

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Section: Rcsultats Et Discussionunclassified

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a-pentalène. XI. Etude par résonance magnétique nucléaire de l'imidazo [1,2-b] pyrazole et du pyrazolo [1,5-a] benzimidazole

Elguero¹,

Fruchier²,

Knutsson³

et al. 1974

Can. J. Chem.

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“…Since the work of Paulsen, 63 it is known that 6-azidolactols undergo a reductive ring-enlargement in the presence of excess hydrogen and a catalyst to yield azepanes. Paulsen Subsequently, Closa and co-workers observed that when the isoxazolidinium salt 28 was subjected to zinc-mediated reduction in aqueous hydrochloric acid followed by treatment with sodium methoxide (NaOMe) in refluxing methanol, the azabicycle 29 was isolated in 53% overall yield as a single isomer.…”

Section: Systems With a 13-oxazepane Corementioning

confidence: 99%

2,8-Diheterobicyclo[3.2.1]octane Ring Systems: Natural Occurrence, Synthesis and Properties

Flores

Dı́ez

2014

Synlett

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This account describes the developments on the synthesis and reactivity of functionalized 2,8-diheterobicyclo[3.2.1]octanes. The continued interest in the chemistry of these compounds is mainly due to their abundance in Nature, being at the core of numerous families of biologically active natural products, and also as a result of their versatile reactivity, which makes them very useful building blocks with considerable impact in modern organic synthesis. The present article is aimed toward providing a comprehensive coverage of the literature on these heterocyclic scaffolds, including our own contributions, and has been organized according to the nature of the heteroatom embedded in the 2,8-bicyclo[3.2.1]octane framework.

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“…69,70 Since then many novel routes have been devised. An asymmetric synthesis using a chiral resolution was reported by Vogel et al (Scheme 2).…”

Section: Noncarbohydrate Routes To 1-deoxynojirimycin (Dnj)mentioning

confidence: 99%

Recent advances in the chemistry of azapyranose sugars

Afarinkia

Bahar

2005

Tetrahedron: Asymmetry

230

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Monosaccharide mit stickstoffhaltigem Ring, XII. Über Monosaccharide mit stickstoffhaltigem Siebenring

Cited by 71 publications

References 17 publications

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a-pentalène. XI. Etude par résonance magnétique nucléaire de l'imidazo [1,2-b] pyrazole et du pyrazolo [1,5-a] benzimidazole

Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a-pentalène. XI. Etude par résonance magnétique nucléaire de l'imidazo [1,2-b] pyrazole et du pyrazolo [1,5-a] benzimidazole

2,8-Diheterobicyclo[3.2.1]octane Ring Systems: Natural Occurrence, Synthesis and Properties

Recent advances in the chemistry of azapyranose sugars

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