Compounds of the formula (I), in which E is O or S; and x is 0 or 1, A is cyclopentyl, cyclohexyl, naphthyl, biphenylyl, anthracyl or an O-, S- or N-containing 5- or 6-membered heterocyclic ring, where the mentioned radicals are unsubstituted or substituted by halogen, C.sub.1 C.sub.4alkyl or C.sub.1 C.sub.4alkoxy; or A is a group formula (II) R is C.sub.1 C.sub.24alkyl, unsubstituted or substituted, C.sub.2 C.sub.24alkyl which is interrupted once or more than once by nonconsecutive O, S or NR.sub.14 and which is unsubstituted or substituted, C.sub.2 C.sub.24alkenyl which is uninterrupted or interrupted once or more than once by nonconsecutive O, S or NR.sub.14 and which is unsubstituted or substituted, C.sub.5 C.sub.24cycloalkenyl which is uninterrupted or interrupted once or more than once by nonconsecutive O, S or NR.sub.14 and which is unsubstituted or substituted; C.sub.7 C.sub.24arylalkyl which is unsubstituted or substituted on the aryl group. C.sub.4 C.sub.24cycloalkyl which is uninterrupted or interrupted once or more then once by O, S or NR.sub.14 and which is unsubstituted or substituted, C.sub.8 C.sub.24arylcycloalkyl or C.sub.8 C.sub.24arylcycloalkenyl; or, R is a group of the formula (III) W is a bond, --CO--O-- or --CO--N(R.sub.15)--; L a di-tri-or tetravalent linking group, n is a number of 2,3 or 4; ##STR00001##