A compound of formula I in which W denotes O or S R denotes an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -OCF 2 -, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, A on each occurrence, identically or differently, denotes a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, and decaline-2,6-diyl, in which one or more non-adjacent CH 2 groups may be replaced by -O- and/or -S- and in which one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 2,6-naphthylene, in which one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, c) the group consisting of 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, thiophene-2,5-diyl, selenophene-2,5-diyl, and 1,2,3,4-tetrahydronanaphthaline-2,6-diyl, each of which may be mono- or polysubstituted by L, d) the group consisting of bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or more H atoms may be replaced by F, L on each occurrence, identically or differently, denotes halogen, cyano, alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl group with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, Z on each occurrence, identically or differently, denotes a single bond, -CF 2 O-, -OCF 2 -, -CH 2 CH 2 -, -CF 2 CF 2 -, -C O-, -OC -, -CH 2 O-, -OCH 2 -, -CF=CH-, -CH=CF-, -CF=CF-, -CH=CH- or -C≡C-, Y 1, Y 2 and Y 3 identically or differently, denote H, F, Cl, CF 3, or CHF 2, wherein one of Y 1 and Y 2 is not H, X denotes F, Cl, CN, NCS, SF 5, fluorinated alkyl, fluorinated alkoxy, fluorinated alkenyl or fluorinated alkenyloxy each having up to 5 C atoms, and n is 0, 1 or 2. W denotes O or S R denotes an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CF 2 O-, -OCF 2 -, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, A on each occurrence, identically or differently, denotes a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, and decaline-2,6-diyl, in which one or more non-adjacent CH 2 groups may be replaced by -O- and/or -S- and in which one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 2,6-naphthylene, in which one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, c) the group consisting of 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, thiophene-2,5-diyl, selenophene-2,5-diyl, and 1,2,3,4-tetrahydronanaphthaline-2,6-diyl, each of which may be mono- or polysubstituted by L, d) the group consisting of bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or more H atoms may be replaced by F, a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, and decaline-2,6-diyl, in which one or more non-adjacent CH 2 groups may be replaced by -O- and/or -S- and in which one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 2,6-naphthylene, in which one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, c) the group consisting of 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, thiophene-2,5-diyl, selenophene-2,5-diyl, and 1,2,3,4-tetrahydronanaphthaline-2,6-diyl, each of which may be mono- or polysubstituted by L, d) the group consisting of bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or more H atoms may be replaced by F, L on each occurrence, identically or differently, denotes halogen, cyano, alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl group with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, Z on each occurrence, identically or differently, denotes a single bond, -CF 2 O-, -OCF 2 -, -CH 2 CH 2 -, -CF 2 CF 2 -, -C O-, -OC -, -CH 2 O-, -OCH 2 -, -CF=CH-, -CH=CF-, -CF=CF-, -CH=CH- or -C≡C-, Y 1, Y 2 and Y 3 identically or differently, denote H, F, Cl, CF 3, or CHF 2, wherein one of Y 1 and Y 2 is not H, X denotes F, Cl, CN, NCS, SF 5, fluorinated alkyl, fluorinated alkoxy, fluorinated alkenyl or fluorinated alkenyloxy each having up to 5 C atoms, and n is 0, 1 or 2.