Synthesis and chromatographic resolution of some chiral four-carbon 2,2′-bridged biphenyls. Some unusually high selectivity factors
5,6,7,8-Tetra hydrodibenzocyclooctene and 14 of its 6-monosubstituted and cis- and trans-6,7-disubstituted derivatives have been prepared and resolved into enantiomers and diastereoisomers on a preparative scale by chromatography on swollen, microcrystalline triacetylcellulose. The solvent and structure dependence of capacity and selectivity factors is discussed in relation to the absolute configurations of the biphenyl units, the orientations of the substituents, and the symmetry of the molecules. Several remarkably high selectivity factors were observed, with 51.6 for the trans-6,7-dimethyl derivative with ethanol as the mobile phase as the most impressive one.