The invention relates to compounds of the formula (I) and also liquid-crystal mixtures comprising these compounds, and their use in liquid-crystal displays: in which R1 is H, F, CF3, OCF3, OCF2H, OCFH2, an alkyl radical or alkyloxy radical or an alkenyl radical or alkenyloxy radical, R2 is H, an alkyl radical or alkyloxy radical or an alkenyl radical or alkenyloxy radical, M1 and M2 are —C(═O)O—, —OC(═O)—, —CH2O—, —OCH2—, —OCF2—, —CF2O—, —C≡C—, —CH2CH2—, —CF2CF2—, —CF═CF—C(═O)O— or a single bond A1 and A2 are &agr;-1,4-diyl, unsubstituted or mono- or disubstituted by F; where &agr; is: phenylene cyclohexane, 1-cyclohexene, or 1,3-dioxane-2,5-diyl m and n are zero or 1; m+n=0 or 1 L1, L2, L3, L4 and L5 are H or F.