Using NMR spectroscopy, the structure of the new products obtained in reaction of ninhydrin-derived azomethine ylide with cyclopropenes was established and conformational mobility was studied. Complete signal assignments in 1 H and 13 C spectra on base analysis of some homo- and heteronuclear correlation spectra were made, and qualitative comparison of the cross-peak intensities in the NOESY spectrum confirmed the structure of compounds 4a – 4c in which three aromatic rings “ a ”, “ b ” and “ c ” at carbons of the cyclopropane ring are facing to us and the side substitute group at carbon C 10 is situated in back direction. The hindered rotations of these aromatic rings in rigid part of molecules under study were found and values of free energy activation ∆ G ≠ of these rotations were evaluated on base coalescence temperature ( T c ) and frequency difference (∆ν) data. The existence of fast in NMR time-scale conformational equilibrium in the solution associated with hindered rotation of side substitute group around C 10 –C 14 bond was proved. In case of adduct 4c, the ratio 68:32 of two preferable conformers has been determined at room temperature in CDCl 3 on base a comparison of calculated and experimental values of vicinal constant 3 J 10 α –14 β . This scalar constant turned out to be 1.0 Hz more for adduct 4a and this reflects an increase in the population of the main conformer almost by 10%. In the NOESY spectra of all studied adducts, a very rare phenomenon of scalar relaxation was found. It manifests itself in appearance of the additional scalar input into the effective cross-relaxation rate between two protons, and in case ω o τ c ≪ 1, it may lead to a change in the sign of the cross-peak to the opposite if the scalar constant between them J H–H turns out to be time-dependent (scalar relaxation of the first kind) or in case of quadrupole nuclear situated near from one of these protons (scalar relaxation of the second kind). Thus, the conformational mobility which is connected with fast (in NMR time scale) nitrogen inversion in five-membered ring of adducts under study was proved due to the presence of the so-called scalar relaxation effects in NOESY spectra which look as a change cross-peak sign in comparison with the usual case.

中文翻译：

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茚三酮衍生的偶氮甲碱叶立德与环丙烯加合物的空间结构和内动力学的核磁共振研究

使用核磁共振光谱，建立了茚三酮衍生的偶氮甲碱叶立德与环丙烯反应所得新产物的结构，并研究了构象迁移率。基于一些同核和异核相关光谱的基础分析，对 1 H 和 13 C 光谱中的信号进行了完整的分配，NOESY 光谱中交叉峰强度的定性比较证实了化合物 4a-4c 的结构，其中三个芳环环丙烷环碳上的“a”、“b”和“c”面向我们，碳C 10 处的侧取代基位于背面。这些芳香环在所研究分子的刚性部分中的受阻旋转被发现，并且这些旋转的自由能活化值 Δ G ≠ 是根据基础聚​​结温度 ( T c ) 和频率差 (Δν) 数据评估的。证明了与侧取代基围绕 C 10 -C 14 键的受阻旋转相关的溶液中存在快速的 NMR 时间尺度构象平衡。在加合物 4c 的情况下，基于邻位常数 3 J 10 α –14 β 的计算值和实验值的比较，已在室温下在 CDCl 3 中确定了两种优选构象异构体的比率 68:32。结果表明，加合物 4a 的标量常数增加了 1.0 Hz，这反映了主要构象异构体的数量增加了近 10%。在所有研究的加合物的 NOESY 谱中，发现了一种非常罕见的标量弛豫现象。它表现为两个质子之间的有效交叉弛豫率的额外标量输入的出现，并且在 ω o τ c ≪ 1 的情况下，它可能导致交叉峰的符号发生相反的变化，如果它们之间的标量常数 JH-H 结果证明是时间相关的（第一类标量弛豫），或者在四极核位于这些质子之一附近的情况下（第二类标量弛豫）。因此，由于 NOESY 光谱中所谓的标量弛豫效应的存在，证明了与所研究的加合物的五元环中的快速（在 NMR 时间尺度上）氮反转有关的构象迁移率，其看起来像一个变化交叉- 与通常情况相比的峰值符号。它表现为两个质子之间的有效交叉弛豫率的额外标量输入的出现，并且在 ω o τ c ≪ 1 的情况下，它可能导致交叉峰的符号发生相反的变化，如果它们之间的标量常数 JH-H 被证明是与时间相关的（第一类标量弛豫），或者在四极核位于这些质子之一附近的情况下（第二类标量弛豫）。因此，由于 NOESY 光谱中所谓的标量弛豫效应的存在，证明了与所研究的加合物的五元环中的快速（在 NMR 时间尺度上）氮反转有关的构象迁移率，其看起来像一个变化交叉- 与通常情况相比的峰值符号。它表现为两个质子之间的有效交叉弛豫率的额外标量输入的出现，并且在 ω o τ c ≪ 1 的情况下，它可能导致交叉峰的符号发生相反的变化，如果它们之间的标量常数 JH-H 被证明是与时间相关的（第一类标量弛豫），或者在四极核位于这些质子之一附近的情况下（第二类标量弛豫）。因此，由于 NOESY 光谱中所谓的标量弛豫效应的存在，证明了与所研究的加合物的五元环中的快速（在 NMR 时间尺度上）氮反转有关的构象迁移率，其看起来像一个变化交叉- 与通常情况相比的峰值符号。