SPIRO UNITS AS BUILDING-BLOCKS IN THERMOTROPIC LIQUID-CRYSTALS - SYNTHESIS AND PHYSICAL-PROPERTIES OF TERMINALLY SUBSTITUTED SPIRO[5.5]UNDECANES

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.