A serendipitous, high yield conversion of norbornenone to tricyclo[3.2.1.0<sup>2,7</sup>]octan-4-one

Ragauskas, Arthur J.; Stothers, J. B.

doi:10.1139/v83-390

Cited by 7 publications

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References 2 publications

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“…Ether was dried over sodium and freshly distilled before use; methyl iodide was dried over 4A sieves. Norbornenone (7) was employed as starting material and its preparation had been described earlier (7).…”

Section: Methodsmentioning

confidence: 99%

¹³C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

Antoniadis¹,

Clements²,

Peiris³

et al. 1987

Can. J. Chem.

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. 65, 1557 (1987).Under homoenolization conditions (I-BuO-/I-BuOH/ 185"C), 3,3-dimethylbicyclo[3.2.l]oct-6-en-2-one (5) is converted into six products through three reaction pathways. The major product, 3,3-dimethylbicyclo[3.3.0]octan-2-one, arises by unidirectional p-enolate rearrangement of 5 to the isomeric unsaturated [3.3.0] ketones, which (a) undergo efficient reduction to 2, by single electron transfer, and (b) suffer Haller-Bauer cleavage to two isomeric 2,2-dimethyl-3-cyclopentenylpropanoic acids. In competition with these processes is the reversible conjugate addition of I-BuO-to 5 to furnish the 6-tert-butoxy derivative, which undergoes p-enolate rearrangement to two isomeric ketones. The structures of these products were established primarily from their ' H and I3C magnetic resonance spectra.GREG A. ANTONIADIS, MICHAEL T. M. CLEMENTS, SRIYAWATHIE PEIRIS et J. B. STOTHERS. Can. J. Chem. 65, 1557.Dans des conditions d'homoCnolisation (I-BuO-/I-BuOH/185"C), la dimethyl-3,3 bicyclo[3.2.1]octkne-6 one-2 (5) se transforme en six produits, par le biais de trois voies rCactionnelles. Le produit principal, la dimethyl-3,3 bicyclo[3.3.0]octanone-2, provient d'une transposition unidirectionnelle du p-Cnolate du compost 5 en cetones [3.3.0] insaturees isomkres (a) qui subissent une reduction efficace en 2 par un transfert unique d'electron et (b) qui subissent un clivage de Haller-Bauer pour conduire a deux acides dimethyl-2,2 cyclopentkne-3 yl propanoi'ques isomkres. Ces processus sont en competition avec ['addition conjuguee reversible de l'anion I-BuO-au compose 5 qui conduit au derive tert-butylate-6 qui subit une transposition P-Cnolique conduisant i deux cetones isomkres. Pour determiner les structures, on a principalement fait appel aux spectres de resonance magnetique nucltaire du 'H et du I3c.[Traduit par la revue]

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Section: Methodsmentioning

confidence: 99%

¹³C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

Antoniadis¹,

Clements²,

Peiris³

et al. 1987

Can. J. Chem.

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“…As an alternative to our earlier route, we reasoned hydroxyketone 10 could be obtained from 12 via C–H oxidation of the methyl proximal to the carbonyl (Scheme ). Inspired by the work of Ragauskas and Stothers, we envisioned synthesizing the tricyclic scaffold via cyclopropanation/homoquadricyclane rearrangement cascade followed by cyclopropane opening . The enantioenriched norbornenone derivative needed for this transformation could be obtained via diastereoselective Diels–Alder cycloaddition of substituted cyclopentadiene with an optically active dienophile.…”

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confidence: 99%

“…Under the reaction conditions, 14 underwent homoquadricyclane rearrangement to give dicyclopropane 19 (Scheme ). Cleavage of the silyl ether in 19 with methanolic n -Bu 4 NOH led to formation of ketone 12 , which was converted in situ to the corresponding oxime 20 by addition of O -methylhydroxylamine hydrochloride to the reaction mixture. Triggered by the work of Sanford and co-workers, the oxime was treated with 15 mol % Pd(OAc) 2 and 2 equiv PhI(OAc) 2 in AcOH–Ac 2 O at 90 °C to effect C–H acetoxylation.…”

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confidence: 99%

Asymmetric Synthesis of the Tricyclooctane Core of Trachylobane Natural Products and Related Terpenoids

et al. 2019

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Enantioselective synthesis of a highly versatile building block en route to trachylobanes and related terpenoids is presented. The synthesis features diastereoselective Diels–Alder cycloaddition reaction, a cyclopropanation/homoquadricyclane rearrangement cascade, and palladium-catalyzed C–H acetoxylation. The targeted tricyclooctane was obtained in 20% yield over 8 steps and in 95% ee. The ketone and alcohol functional groups serve as handles for further elaboration.

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“…The I3C spectrum contained three methylene signals (6c 5.4, 9.9, 32. l), five methine peaks (20.6, 22.1, 28.3, 3 1 .O, 39.6), two quaternary signals (23.1, 69.6), and trimethylsilyl absorption at zc 1.1. On comparison with the results for 4, these data are consistent with the expected homoquadricyclene structure.…”

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confidence: 99%

¹³C magnetic resonance studies. 119. Tricyclo[3.3.0.0] and [3.2.1.0]octanones from substituted norbornenones via cyclopropanation and homoketonization

Ragauskas¹,

Stothers²

1985

Can. J. Chem.

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ARTHUR J. RAGAUSKAS and J. B. STOTHERS. Can. J. Chem. 63, 2961 (1 985). Simmons-Smith cyclopropanation of the trirnethylsilyl enol ethers of 7-isopropylidene-and two 7-spirocyclopropylnorbornenones leads directly to the 8-substituted 2-trimethylsilyl ethers of hornoquadricyclene. Homoketonization of the unsaturated ether proceeds regiospecifically to the corresponding tricyclo[3.3.0.02~H]octan-4-one while the others give the tricyclo[3.2.1 .02.6]octan-4-ones exclusively, all with high stereoselectivity favoring inversion of configuration. This difference in the regiochemistry of homoketonization can be attributed to a directive effect of P-functionalization overcoming thermodynamic control of cleavage. ARTHUR J. RAGAUSKAS et J. B. STOTHERS. Can. J. Chem. 63, 2961 (1985). La reaction de cyclopropanation suivant Simmons-Smith des Cthers Cnoliques trimCthylesilyles de l'isopropylidene-7 et de deux spiro-7,cyclopropylnorbornCnones conduit directement aux Cthers trimCthylsily1-2 de I'homoquadricyclene substitues en position 8. L'homocCtonisation de 1'Cther insaturC est rCgiospCcifique et conduit a la tricyclo[3.3.0.02~x]octanone-4 correspondante tandis que les autres Cthers conduisent exclusivement aux tricyclo[3.2.1 .02'6]octanones-4; toutes ces reactions se produisent avec une tres haute stCrCosClectivitC qui favorise une inversion de configuration. On attribue la diffkrence de rCgiochimie dans I'homocttonisation a un effet directif de la fonction en P qui est plus puissant que le contr6le thermodynamique du clivage.[Traduit par le journal]

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A serendipitous, high yield conversion of norbornenone to tricyclo[3.2.1.0^2,7]octan-4-one

Cited by 7 publications

References 2 publications

¹³C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

¹³C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

Asymmetric Synthesis of the Tricyclooctane Core of Trachylobane Natural Products and Related Terpenoids

¹³C magnetic resonance studies. 119. Tricyclo[3.3.0.0] and [3.2.1.0]octanones from substituted norbornenones via cyclopropanation and homoketonization

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A serendipitous, high yield conversion of norbornenone to tricyclo[3.2.1.02,7]octan-4-one

Cited by 7 publications

References 2 publications

13C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

13C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

Asymmetric Synthesis of the Tricyclooctane Core of Trachylobane Natural Products and Related Terpenoids

13C magnetic resonance studies. 119. Tricyclo[3.3.0.0] and [3.2.1.0]octanones from substituted norbornenones via cyclopropanation and homoketonization

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A serendipitous, high yield conversion of norbornenone to tricyclo[3.2.1.0^2,7]octan-4-one

¹³C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

¹³C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

¹³C magnetic resonance studies. 119. Tricyclo[3.3.0.0] and [3.2.1.0]octanones from substituted norbornenones via cyclopropanation and homoketonization