Liquid Crystals With a Chiral Core: Cyclohexene Carboxylates

A series of new liquid crystals containing a cyclohexene ring have been synthesized and characterized. The cyclohexene ring is formed by the Diels-Alder reaction between myrcene and methyl acrylate, and has a chiral center. Hydrolysis of the resulting methyl ester into the corresponding acid and esterification of the latter with 4-hydroxy-4′-n-alkoxybiphenyl yields a homologous series of liquid crystals with the structure: The compounds thus prepared are racemic mixtures. The lower members of this series (n = 1 and 2) have a large nematic range, and the higher members (n = 3–10) have multiple smectic phases in addition to the nematic phase. When (1R,2S,5R)-(-)-menthyl acrylate was used instead of methyl acrylate in the Diels-Alder synthesis, optically active compounds with 40% enantiomeric excess were obtained.