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|Título:||13C NMR of 4,5-epoxy-3-substituted decalin and analogous ?4-octalin derivatives: Epoxide- and methyl-induced shifts|
|Autor(es):||Adrian Martin Pohlit|
Helena Maria Carvalho Ferraz
|Assunto:||ressonância magnética núclear|
deslocamento quimico induzido
|Revista:||Magnetic Resonance in Chemistry|
|Resumo:||Fully assigned 13C NMR chemical shifts for 4,5-epoxy-3-keto-, -3-hydroxy-, and -3-acetoxydecalins and -10-methyldecalins, Δ4-octalins and 10-methyl-Δ4-octalins are reported together with epoxide- and methyl-induced shifts. The 4,5α- and 4,5β-epoxydecalins present epoxide γ shielding in the A ring consistent in general with the syn-axial hydrogen rule. The 4,5α- and 4,5β-epoxy-10-methyldecalins present only slightly different shielding effects at γ-carbons C-1, C-2, C-7, C-9 and C-11. Methyl-induced shifts in 4,5α- and 4,5β-epoxy-10-methyldecalins are similar at all carbons to those for trans- and cis-decalins (low temperature in the case of the latter), respectively, suggesting the predominance of the transoid and cisoid A ring conformations, respectively, in these epoxides. The methyl-induced shifts in the A ring of octalin analogues are intermediate between those of the two epoxide configurational isomers. Epoxide γ-anti deshielding and γ-syn shielding (analogous to those in 5-hydroxydecalins) are evident when comparison is made with 13C shifts from analogous decalins, in contrast to the result when these effects are evaluated with data for Δ4-octalin analogues.|
|Aparece nas coleções:||Coordenação de Tecnologia e Inovação (COTI)|
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