Optically active compound and liquid crystal composition containing the compound

Field of the Invention An optically active compound containing 5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-bi-2-naphthol of the general formula (1) as an asymmetric source, wherein n is an integer of 1 to 10, Y is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a phenyl group, a phenyl group substituted with an alkyl group having 1 to 5 carbon atoms or a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, X is a single bond (-), -OOC- or -OCH-, and each of A and B is a substituent formed by specifically combining rings selected from cyclohexane, benzene, pyrimidine, naphthalene, dioxane, etc., including mutual bonding forms of rings so that the substituent has 1 to 4 rings, the optically active compound characteristically having a large helical twisting power (HTP) of 50 or more and being useful as a chiaral dopant, the chiral dopant being capable of adjusting a helical pitch when only added in a small amount, so that the deterioration of performances of a base liquid crystal can be prevented.