Analise conformacional por ressonancia magnetica nuclear e calculos teoricos de metilenocicloexanos 2-substituidos / Conformational analysis by nuclear magnetic resonance and theoretical calculations in 2-substituted methylenecyclohexane

AUTOR(ES)

Pedro Renato Anizelli

DATA DE PUBLICAÇÃO

2008

RESUMO

Conformational preferences for 2-fluoro-methylenecyclohexane (1), 2-chloromethylenecyclohexane (2), 2-bromomethylenecyclohexane (3), 2-N,N-dimethylaminomethylenecyclohexane (4) and 2-methoxymethylenecyclohexane (5) were determined using JHH spin-spin coupling constants, while stereoelectronic interactions were obtained by means of theoretical calculations and NBO (natural bond orbital) analysis. The conformational equilibrium of compounds 1-5 can be represented by their axial and equatorial conformers. The axial conformers for 1-5 are stable in polar and non-polar solvents. These conformational preferences were attributed to the hyperconjugative interactions between the p(C1-C7)s*(C2-Xax), s(C3-Hax)s*(C2-Xax) and (LP3Xax)p*(C1-C7) orbitals, and the repulsive steric interaction observed between s(C7-H)(LP3Xeq).

ASSUNTO(S)

conformational analysis rmn nmr methyilenecyclohexane analise conformacional metilenociclexanos

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