New Liquid Crystalline Compounds Based on Thiophene.

A homologous series of 2-alkyl-5-(4′-cyanophenyl)thiophenes has been prepared and shown to have improved properties for use in liquid crystal displays. The thiophene ring is prepared from a 1-(4′-bromophenyl)-1,4-dioxoalkane, constructed using the Stetter procedure, by the action of Lawesson’s reagent, and the cyano-group is finally introduced using a copper(I)-mediated exchange reaction.