Semiempirical and ab initio calculations versus dynamic NMR on conformational analysis of cyclohexyl-N,N-dimethylcarbamate

Journal of the Brazilian Chemical Society

Universidade Estadual de Maringá, Maringá, Brazil¹  Caetano, Josiane¹  Basso, Ernani A.¹  Oliveira, Paulo R.¹  Schuquel, Ivânia T. A.¹ 

关键词: conformational analysis;    theoretical calculations;    cyclohexane derivative;    dynamic NMR;   

DOI  :  10.1590/S0103-50532001000200015

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

The conformational analysis of six-membered rings has provided the foundation for modern stereochemistry investigation of the factors that determine conformational preferences of substituents on saturated six-membered rings (A values)1,2 and have enriched our understanding of how atoms and functional groups interact with hidrocarbons fragments.The conformational preference of a monosubstituted cyclohexane is determined largely by the interaction of the substituent with the syn-axial protons and the carbons to which the latter are attached.There have been numerous studies aimed at determining the conformational preferences of monosubstituted cyclohexanes, and a wide range of different substituents were investigated3,4. As well known, when the time scale of observation is relatively long, the two forms equilibrate (eq. 1) and render measurements of distinct conformations impossible.The most used methodology investigating this equilibrium have been NMR spectroscopy which involves low temperature experiments on which the equilibration is "slow" and the conformations may be observed individually. In that

【 授权许可】

Unknown