Spiro units as building blocks in thermotropic liquid crystals: Synthesis and physical properties of terminally substituted spiro[5.5]undecanes

Abstract

Abstract A number of terminally substituted spiranes were prepared from 9‐pentyl‐3‐spiro[5.5]undecanone ( 7 ), which was obtained in a five‐step synthesis starting from 4‐pentylcyclohexanone ( 1 ), using an intramolecular cyclisation with 4‐toluenesulfonylmethyl isocyanide (TosMIC) as a key step. By a comparison of the physical data of the new spiro[5.5]undecane derivatives I with those of several well‐known, analogous substituted compounds – solely differing in their central building unit – conclusions regarding the effects of the spiro ring system on its mesogenic potential are drawn.