Compounds for a liquid-crystalline medium, and the use thereof for high-frequency components

Compounds of the formula I

• in which
• A1-5, independently of one another, denote
• a) a radical of the formula
• b) 1,4-phenylene, in which one or more CH groups may be replaced by N,
• c) trans-1,4-cyclohexylene or cyclohexenylene, in which, in addition, one or two non-adjacent CH2 groups may be replaced by —O— and/or —S— and in which H may be replaced by F,
• or
• d) a radical from the group 1,4-bicyclo[2.2.2]octylene, cyclobut-1,3-diyl, spiro[3.3]heptane-2,6-diyl, thiophene-2,5-diyl, thiophene-2,4-diyl, furan-2,5-diyl, furan-2,4-diyl,
• and in which, in groups a), b), c) and d),
• one or more H atoms may also be replaced by Br, Cl, F, CN, —NCS, —SCN, SF5, C1-C10 alkyl, C1-C10 alkoxy or a mono- or polyfluorinated C1-C10 alkyl or alkoxy group,
• and where
• at least one radical from A1 to A5 represents a radical according to a),
• R1 and R2 each, independently of one another, denote a halogenated or unsubstituted alkyl radical having 1 to 15 C atoms, where, in addition, one or more CH2 groups in these radicals may each be replaced, independently of one another, by —C≡—, —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —(CO)O—, —O(CO)—, —(CO)—, —O— or —S— in such a way that O or S atoms are not linked directly to one another,
• or F, Cl, Br, CN, CF3, OCF3, SCN, NCS or SF5,
• Z2 denotes C≡C— or
• Y1, Y2, independently of one another, denote H, F, Cl, C1-C10 alkyl,
• Z1, Z5, independently of one another, denote a single bond, —C≡C—, —CH═CH—, —CH2O—, —(CO)O—, —CF2O—, —CF2CF2—, —CH2CF2—, —CH2CH2—, —(CH2)4—, —CH═CF— or —CF═CF—, where asymmetrical bridges may be oriented to both sides, and
• m, n, independently of one another, denote 0, 1 or 2.