Structural studies on optical resolution via diastereoisomeric salt formation, part 2. The conformational flexibility of (S)-2-benzylaminobutan-1-ol in enantiomer separation for permethrinic acids

Abstract

The optical resolution of trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid (1) with (S)-2-benzylaminobutanol (2) has been optimized. Thermodynamic constants, thermal behaviour, and the crystal structures of the diastereoisomeric salts were determined in order to evaluate the results of optical resolution. The resolving agent (2) exists in four different conformations in the diastereoisomeric salts of (1) and its cis isomer. The relative energies of these four rotamers have been studied by means of force-field calculations.