Liquid-crystalline medium and liquid-crystal display having high twist

A liquid-crystalline medium having a helically twisted structure comprising:

• a nematic component and an optically active component, wherein
• said optically active component comprises one or more chiral compounds whose helical twisting power and concentration are selected in such a way that the helix pitch of the medium is ≦1 μm, and
• said nematic component comprises one or more compounds of formula I,
• in which
• R1 is H or an alkyl or alkenyl radical having up to 20 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, and wherein one or more CH2 groups are each, independently of one another, optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH— or —C≡C— in such a way that O atoms are not linked directly to one another,
• is
• X0 F, Cl or alkyl, alkenyl or alkoxy each of which is halogenated and has up to 6 C-atoms, and
• L1-6 are each, independently of one another, H or F.