Oxabicyclooctanes

An oxabicyclooctane compound of the formula I

• 135
• in which
• L1 and L2, independently of one another, are H or F,
• R1 and R2, independently of one another, are CN or halogen or alkyl having from 1 to 12 C atoms which is unsubstituted or mono- to perhalo-substituted by halogen, CN or CF3, optionally one or more CH2 groups being replaced, in each case independently of one another, by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—, —CH═CF—, —CF═CF—, —C≡C— or 1,3-cyclobutylene in such a way that S and/or O atoms are not linked directly to one another,
• A1-4 are, independently of one another:
• trans-1,4-cyclohexylene, in which one or two nonadjacent CH2 groups are optionally replaced by —O—, and/or —S—;
• 1,4-phenylene, in which one or two CH groups are optionally replaced by N;
• 1,4-cyclohexenylene;
• 1,4-bicyclo-(2,2,2)-octylene;
• piperidine-1,4-diyl-;
• naphthalene-2,6-diyl;
• decahydronaphthalene-2,6-diyl;
• or 1,2,3,4-tetrahydronaphthalene-2,6-diyl;
• where the rings in the above are optionally monosubstituted or polysubstituted by F, CL, CN, CF3,
• Z1 and Z2 each, independently of one another, are —CH2O—, —OCH2—, —CF2O—, —OCF2—, —COO—, —OCO—, —CF2CF2—, —CH2CH2—, —(CH2)4—, —(CH2)3O—, —O(CH2)3—, —CF2CH2—, —CH═CH—, —CH═CF—, —CF═CF—, —C≡C— or a single bond,
• n1 is 0 or 1,
• n2 is 0 or 1, and
• n3 is 0, 1 or 2,
• with the proviso that n1=0, if n2=0.