Desaminierungsreaktionen, 48. Zerfall von 5‐ und 6‐Alkoxy‐2‐norbornandiazonium‐Ionen

Kirmse, Wolfgang; Siegfried, Rainer; Feldmann, Georg; Schoen, S.; Schwarz, Johannes

doi:10.1002/cber.19881210315

Cited by 8 publications

(2 citation statements)

References 42 publications

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“…H-6a for 2,12,13, 21-23, 29, and 30 (ddd,_/ = 6, 6, 12), for 3, 24, and 31 (ddj = 4, 17), forl4(dd J = 4, 16), for 17(ddJ = 4, 17), for25(ddd,y= 1,4,17). -6ß 2,12,13, 21-23, 29, and 30 (ddd,_/ = 2, 12, 12), for 3, 24, and 31 (dddj = 1, 3, 17), for l4(dd,y = 3, 16), for 17(ddJ = 3, 17), for25(brddJ= 3,17). H-7(ddJ = 6, 11).…”

Section: Resultsmentioning

confidence: 99%

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Molecular Rearrangements in the Longipinene Series

Román¹,

Hernández²,

Cerda-Garcı́a-Rojas³

et al. 1992

J. Nat. Prod.

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Section: Resultsmentioning

confidence: 99%

“…Recrystallizations from CHCl3/hexane gave the analytical sample: mp 158-160°; ir v max 1710 (C=0), 1670 and 1635 cm-1 (C=C-C=0); C77.55,H8.68,0 13.78; found C 77.41, H 8.53,0 13.93%. When reflux was maintained for 6 h, only moreli-3-ene-2,7-dione [3] in 93% yield was obtained.…”

Section: )mentioning

confidence: 99%

Molecular Rearrangements in the Longipinene Series

Román¹,

Hernández²,

Cerda-Garcı́a-Rojas³

et al. 1992

J. Nat. Prod.

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Rearrangements of Spirocyclobutane-Substituted 2-Norbornyl Cations

Kirmse¹,

Landscheidt²,

Siegfried³

1998

Eur. J. Org. Chem.

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2‐Norbornyl cations with spiroannellated cyclobutane rings were generated for comparison with the previously studied cyclopropane analogues. Starting with the Diels‐Alder reaction of cyclopentadiene with methylenecyclobutane, spiro‐ [bicyclo[2.2.1]heptane‐2,1′‐cyclobutan]‐6‐one (11) was prepared. The tosylhydrazone 12 of 11 was photolyzed in NaOD/D2O to give the analogous alcohol 13 with a ca. 1:1 distribution of deuterium. Ring expansion was not observed, in contrast to the cyclopropane analogue. − The tosylhydrazone 22 of spiro[bicyclo[2.2.1]heptane‐2,1′‐cyclobutan]‐3‐one (21) and the related tosylates (28, 32) rearranged, in part, to afford derivatives of spiro[bicyclo[2.2.1]heptane‐7,1′‐cyclobutane] (29, 33, 34). In both series, ring expansion of the spiroannellated cyclobutane, by exo‐3,2‐C shift, was the major reaction, giving rise to a uniquely endo‐selective tertiary cation (36). Analogously positioned cyclopropane rings remain intact, due to stabilizing interactions with the neighboring positive charge which are lacking in the cyclobutane systems. − In CDCl3 solution, the tosylate 32 produced mixtures of isomeric tosylates by way of ion pair recombination. We observed that exo → exo shifts of the counterion proceed with little scrambling of 18O whereas complete equilibration of the tosylate oxygens is attained in exo → endo shifts.

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Desaminierungsreaktionen, 49. Zerfall von 2‐Oxa‐5‐ und ‐6‐norbornandiazonium‐Ionen

Kirmse

Mrotzeck

1988

Chem. Ber.

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Das Verhalten von 2-Oxad-norbornandiazonium-Ionen (19, ZO) entspricht dem der analogen Brosylate (7, 11). Belichtung des Tosylhydrazons 17 in Natmnlauge ergibt 2-Oxa-exo-6-norbornanol(15) ohne das endo-Isomere 22. Das in D20/DONa eingbaute Deuterium verteilt sich gleichmaBig auf die Positionen 1 und 6 -ein Hinweis auf das tricyclische Oxonium-Ion 8 als Zwischenstufe. -Nach vielen vergeblichen Versuchen erhielten wir 2-Oxa-exo-5-norbornawl (45a) aus cis4Hydroxy-2-cyclopenten-1-methanol (41 a), &em Prins-Produkt des Cyclopentadiens, durch. Addition von 2-Chlorethanol, Cyclisierung des primiiren Brosylats und Abspaltung der Schutzgruppe mit n-Butyl- In der Chemie der Carbokationen spielen alkylverbruckte Strukturen (eckenprotonierte Cyclopropane) eine wichtige Rolle2'. Zusammenhange zwischen Konstitution und Verbruckung bicyclischer Carbokationen sind jedoch noch wenig untersucht. Neben Ringspannung') und sterischen Effekten4' interessiert uns der EinfluB von Substituenten am potentiell pentakoordinierten Kohlenstoff '). Alkoxygruppen an C-6 des 2-Norbornyl-Kations trugen zu dieser Problematik wenig bei, da die Wagner-Meerwein-Umlagerung von 1 durch Fragmentierung (1 -+ 2 4 3) und Nachbargruppenbeteiligung des Sauerstoffs (1 + 4 + 5) uberlagert ist 'I. IOU8The reactivity of 2-oxa-6-norbornanediazonk~11 ions (19.20) conforms to that of the analogous brosylates (7, 11). Photolysis of the tasylhydrazone 17 in aqueous sodium hydroxide yields 2-0xa-exo-6-norbornanol (15) with no endo isomer 22. The deuterium incorporated from D20/DONa is distributed equally between positions l and 6 of 15, suggesting.the tricyclic oxonium ion 8 as an intermediate. -After many fortuitous attempts, 2-oxa-exo-5-norbornanol (&a) was prepared from cis4hydroxy-2-cyclopcntene-l-methanol (41 a), a hins product Df cyclopentadiene. by addition of 2chloroethanol, cyclization of the primary brosylate, and removal of the protecting group with n-butyllithium. The tosylhydrazone 47, obtained via ketone 25, gave 99% of 458 on irradiation. Deviations from equidistribution of a deuterium label were slight (5-D:4-D = 1.1 -1.2). The small effect of the internal oxygen substituent in cation 50 stands in contrast to the much stronger effect of 6-akoxy groups on 2-norbornyl cations (52)'). A rationale is provided by the conformationdependent ibteraction of akoxy groups with protonated cyclopropanes, as calculated by Schleyer et al. ihre Solvolysen sind bereits bekannt 6.n. Die Acetolysegeschwindigkeiten der endo-Brosylate 10 und 11 machen den induktiven Effekt des Sauerstoffs deutlich. Er wird in der exo-Reihe (6, 7) durch Nachbargruppenbeteiligung iiberkompensiert, so daB fur 7, 11 ein sehr hohes exo:endo-Geschwindigkeitsverhaltnis (7 . lo7) resultiert6! Die kinetischen k,,l .O 1.10-5Daten, die ausschlieBliche Bildung von 2-Oxa-exo-6-norbornyl-Produkten (9) und die gleichmal3ige Verteilung einer 6-D-Markierung in 77' und 116) auf C-1 und C-6 von 9 sprechen fur ein symrnetrisches Oxonium-Ion 8 als Zwischenstufe. Hier war lediglich zu prufen, ob 2-Oxa-6-nor...

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Desaminierungsreaktionen, 48. Zerfall von 5‐ und 6‐Alkoxy‐2‐norbornandiazonium‐Ionen

Cited by 8 publications

References 42 publications

Molecular Rearrangements in the Longipinene Series

Molecular Rearrangements in the Longipinene Series

Rearrangements of Spirocyclobutane-Substituted 2-Norbornyl Cations

Desaminierungsreaktionen, 49. Zerfall von 2‐Oxa‐5‐ und ‐6‐norbornandiazonium‐Ionen

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