Ganguly B, Freed D A, Kozlowski M C
Department of Chemistry, Roy and Diana Vagelos Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Org Chem. 2001 Feb 23;66(4):1103-8. doi: 10.1021/jo000580i.
1,5-Diaza-cis-decalin populates two conformations in which the nitrogen atoms are either gauche (N-in) or anti (N-out) to one another. The equilibrium mixture of the two conformers depends on the substituents at the nitrogen atom, as well as the reaction conditions. Ab initio (HF/6-31G, B3LYP/6-31+G) and molecular mechanics (Amber) calculations have been performed to examine the possible role of stereoelectronics and steric effects in controlling the equilibrium of substituted 1,5-diaza-cis-decalins. In the present study, N,N'-diethyl- and N,N'-bistrifluoroethyl-1,5-diaza-cis-decalins have been synthesized, and the equilibrium mixtures have been measured using 1H and 13C NMR experiments. Steric effects appear to control the equilibria between the two conformational isomers of 1,5-diaza-cis-decalin while torsional effects appear to dominate the equilibria for the N,N'-dialkyl derivatives.
1,5-二氮杂顺式十氢化萘存在两种构象，其中氮原子彼此呈邻位交叉（N-内型）或反式（N-外型）。这两种构象异构体的平衡混合物取决于氮原子上的取代基以及反应条件。已进行了从头算（HF/6-31G，B3LYP/6-31+G）和分子力学（Amber）计算，以研究立体电子效应和空间效应在控制取代的1,5-二氮杂顺式十氢化萘平衡中的可能作用。在本研究中，已合成了N,N'-二乙基-和N,N'-双三氟乙基-1,5-二氮杂顺式十氢化萘，并使用1H和13C NMR实验测量了平衡混合物。空间效应似乎控制着1,5-二氮杂顺式十氢化萘两种构象异构体之间的平衡，而扭转效应似乎在N,N'-二烷基衍生物的平衡中占主导地位。
