Atropisomerism of 1-alkylcyclohepta [b]pyrrol-2(1H)-ones. Isolation of the rotational isomers of 1-(2,4-dimethyl-3-pentyl)cyclohepta [b]pyrrol-2(1H)-one
作者:Yukari Ikeda、Nobuo Kato、Akira Mori、Hitoshi Takeshita
DOI:10.1002/mrc.1260300604
日期:1992.6
1-Alkylcyclohepta[b]pyrrol-2(1H)-ones showed rotational isomerism around the CN bond. Two rotamers of the 1-(2,4-dimethyl-3-pentyl) derivative were isolable by high-performance liquid chromatography at 0°C. The activation free energy, measured by the line-shape analysis of the variable-temperature NMR spectra, was 86.8 kJ mol−1 at 25°C. In a bromo derivative, a positive buttressing effect was observed.
1 烷基环庚基[b]吡咯-2(1H)-酮显示出围绕 CN 键的旋转异构现象。1-(2,4 二甲基-3-戊基)衍生物的两种旋转异构体可在 0°C 下通过高效液相色谱法分离出来。通过对变温核磁共振光谱进行线形分析测得的活化自由能在 25°C 时为 86.8 kJ mol-1。在一种溴衍生物中,观察到了一种正的对接效应。