NEW SYNTHESIS OF THE LIQUID-CRYSTALLINE BICYCLOHEXYLBENZENE DERIVATIVES

A new improved approach to prepare the liquid crystalline bicyclohexyl benzene derivatives is proposed. The key stage is the synthesis of 3-( trans-4-arylcyclohexyl)-6-alkyl (or aryl) cyclohex-2-en-1-ones via the condensation of the corresponding Mannich salts with 2-substituted ac etoacetic esters (or methyl benzyl ketones) in the presence of a base. The catalytic hydrogenation of these cyclohexenones in base media giv es mainly saturated trans-ketones which are promising semiproducts for the preparation of different kinds of the LC compounds containing a b icyclohexyl fragment. The chemical transformations of the prepared cyc lohexanones were carried out and as a result a range of LC compounds b oth known and new ones were synthesized.