Chiral β-hydroxycarbonyl compounds based on (-)-menthone: structure and behavior in liquid crystalline systems

Article abstract of DOI:10.1007/BF00700889

It has been established by X-ray structural analysis that 2-(1'-biphenyl-4-yl-1'-hydroxy)methyl-p-menthan-3-one, one of the products of the reaction of (-)-menthone triisopropyloxytitanium enolate with 4-phenylbenzaldehyde, has a 1R,2S,4S,1'S configuration.In crystals, this β-hydroxyketone adopts a chair conformation with equatorial methyl and isopropyl groups and an axial 2-(1'-biphenyl-4-yl-1'-hydroxy)methyl substituent.Unlike the stereoisomeric compound with the 1R,2R,4S,1'S configuration, the exocyclic fragment of which has an intramolecular >C=O...H-O- hydrogen bond in crystals and solutions, in the crystals of the 1R,2S,4S,1'S ketol under study, molecules are linked by a network of cooperative -O-H...O-H...O-H... hydrogen bonds.Based on the results of molecular mechanics calculations and experimental data of 1H NMR and IR spectroscopy, conformations of molecules of this compound, which are in equilibrium in solution, have been characterized.Based on data on spatial structures of stereoisomeric β-hydroxyketones and the character of H-bonds formed by these compounds, the characteristic features of the effect of these chiral alloying additives on the supramolecular structure and macroscopic properties of liquid crystalline system have been interpreted. - Keywords: stereoisomeric 2-(1'-biphenyl-4-yl-1'-hydroxy)methyl-p-menthan-3-ones; molecular structure; X-ray structural analysis; crystal structure; conformational analysis; molecular mechanics; hydrogen bond; induced cholesteric liquid crystals, twisting power.