13 C Nuclear Magnetic Resonance Studies. 45. The 13 C Spectra of Some β,γ Unsaturated Polycyclic Ketones

. 62, 1751 (1984).syn-and anti-7-lsopropyl-2-norbornanone (5 and 6) were prepared by catalytic hydrogenation of 7-isopropylidene-2-norbornanone; syri-and anti-7-benzhydryl-2-norbornane (9 and 10) were prepared in analogous fashion. Kctones 5 and 6 and syrl-and arlti-7-tert-butyl-2-norbornanone (7 and 8) were converted to the corresponding 3-diazo-2-norbornanones 1-4 via the monotosylhydrazones 44-47 of the corresponding a-diketones 40-43. The 'H and "C nmr spcctra of 1-10,40-47, and thcir precursors have been analyzed. The 'H nmr spectra of the diazo ketones 1-4 have their C-I and C-4 bridgehead proton signals shifted to higher and lower field, respectively, relative to the bridgehead signals of thc corresponding dikctones. Thc "C nmr spectra of all pairs of bicyclic epimers shown y-garrche shielding effects by the 7-substitucnt at (sp3) C-3 in thc syrl compounds and at C-5 and C-6 in the arlti compounds. A converse effect is found at (sp') C-2 (and C-3 in the diketoncs). Comparison of the magnitude of the shielding effects of C-7 methyl, isopropyl, benzhydryl, and tert-butyl substituents gives evidence of 6 deshielding effects at C-3 in the syrl compounds and at C-5 and C-6 in thc onti compounds by methyl substitucnts on C-8.PETER YATES et JOHN DAVID KRONIS. Can. J. Chem. 62, 1751 (1984.On a prCparC Ics isopropyl-7 norbornanones-2 syrl et anti (5 et 6) par hydrogenation catalytique de I'isopropylidene-7 norbornanone-2; on a prCparC les benzhydryl-7 norbornanones-2 syrl et nrlti (9 et 10) d'unc manikre semblablc. On a transform6 les cCtones 5 et 6 ainsi que les tert-butyl-7 norbornanones-2 sytl et anti (7 et 8) en leurs diazo-3 norbornanones-2 correspondantes (1-4) par le biais des monotosylhydrazones 44-47 des a-dicCtones correspondantes 40-43. On a analysC les spectrcs rmn du ' H et du "C des composCs 1-10 et 40-47 et de leurs prCcurseurs. Dans les spectres rmn du 'H des diazocCtones 1-4, les signaux des protons en tCte de pont (C-l et C-4) sont dCplacCs respectivcment vers des champs plus haut et plus bas, par rapport aux signaux des protons dans les positions Cquivalentes des dicttones correspondantes. Les spectrcs rmn du '.'c de chacune des paires d'Cpimkres bicycliques prtsentent tous des effets de blindage y-gauche, dus aux substituants en position 7 et affectant la position C-3 (sp3) des composCs syrl et les positions C-5 et C-6 dcs composts anti. On observe un effet inverse au niveau de C-2 (sp') (et de C-3 dans les dicttones). Une comparaison de I'amplitude dcs cffets de blindage provoquCs par les substituants mCthyle, isopropyle, benzhydrylc et tert-butyle en C-7 suggkre que les substituants mCthyles cn C-8 provoquent des effets de dtblindage 6 en C-3 dans les composCs syn et en C-5 et C-6 dans les composCs anti.[Traduit par le journal]In connection with our studies on the acid-catalyzed decomposition of a-diazo ketones (1, 2), we required pairs of 3-diazo-2-norbornanones with bulky syt7-and anti-7 substituents. We describe here the synthesis of the diazo ketones 1-4, prepared for this purpose, and di...

Section: A1203mentioning

confidence: 99%

Section: C Nuclear Magnetic Resonance Spectramentioning

confidence: 99%

Aliphatic diazo compounds. XIV. The synthesis of 7-substituted 3-diazo-2-norbornanones and the infrared and proton and carbon-13 nuclear magnetic resonance spectra of these diazo ketones and their precursors

Yates¹,

Kronis²

1984

“…En particulier les dtplacements chimiques B champ fort de rarbones situts en y de groupes mtthyles et tclipsts par ceux-ci sont dus des interactions steriques (4). L'influence du groupe hydroxyle a t t t ttudite dans les systkmes bicycliques conformationnellement fixes (strie bicyclo[2.2.1]-heptanique ou -[2.2.2]octanique, strie de l'adamantane) ou peu flexibles (strie bicyclo[3.2.1 Ioctanique) (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Dans des series de dtcalols (17) et de sttroides (17,18), l'influence du groupe OH sur les carbones en y et en 6 de ce substituant a aussi t t t ttudite; des effets y de -3.3 B -7.3 ppm ont pu ainsi Etre mis en tvidence.…”

Section: Introductionunclassified

Résonance magnétique nucléaire du carbone-13 de composes oxa- et azabicyclo[3.3.1]- et -[4.2.1]nonaniques

Barrelle¹,

Apparu²,

Gey³

1978

.l]nonan-2-ols, provide supplementary inforniation regarding the previously studied structures of these types. Shielding and deshielding due to y and 6 steric interactions wereobserved depending on the substituent. The study of the oxabicyclo[4.2.1]nonanes, substituted or not substituted in positions 2 and 7 by hydroxyl groups, and of the azabicyclo[4.2.1]-nonanes substituted in position 2 by the same group, yields interesting results on the conformational equilibria in these compounds which is caused by the flexibility of the sevenmembered ring. The conformational equilibrium is displaced toward the boat form of the seven-membered ring for the unsubstituted compounds. Goirche conformations are proposed for the other compounds in order to account for the experimental observations; the pure chair and boat forms are excluded. Two ketones also have been studied.[Journal translation] Introduction Les effets de substituants sur les dtplacements chimiques en rmn du 13C ont t t t trts ttudits et peuvent apporter d'importants renseignements d'ordre sttrtochimique (1-3). En particulier les dtplacements

“…The combined extracts were dried over MgS04. Evaporation of the solvent gave a yellow oil (6.3 g, 70%) that was a 1:l mixture of two major components, by glc analysis (DEGS), which were identified as 10 and 11 by I3cmr (10). The crude product was subjected to flash chromatography 20:80) to remove traces of minor impurities before the methylation step.…”

Section: Bicyclo[32 L]oct-6-en-2-and -3-ones (10 11)mentioning

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

Self Cite

. 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]