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Atropisomerism of 1‐alkylcyclohepta [ b ]pyrrol‐2(1 H )‐ones. Isolation of the rotational isomers of 1‐(2,4‐dimethyl‐3‐pentyl)cyclohepta [ b ]pyrrol‐2(1 H )‐one
Author(s) -
Ikeda Yukari,
Kato Nobuo,
Mori Akira,
Takeshita Hitoshi
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260300604
Subject(s) - chemistry , atropisomer , conformational isomerism , derivative (finance) , stereochemistry , nuclear magnetic resonance spectroscopy , medicinal chemistry , molecule , organic chemistry , financial economics , economics
1‐Alkylcyclohepta[ b ]pyrrol‐2(1 H )‐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.