Compounds of the formula ##STR1## wherein R.sup.1 and R.sup.2 each independently are lower-alkyl; or together are alkylene with 3-5 C-atoms in a straight chain; one of the residues R.sup.3 and R.sup.4 is hydrogen and the other is hydrogen or lower-alkyl; R.sup.6 and R.sup.7 are hydrogen or lower-alkyl; R.sup.5 and R.sup.8 are hydrogen, lower-alkyl, lower-alkoxy or halogen; X signifies --O--, --S--, --SO--, --SO.sub.2 -- or --NR.sup.9 ; R.sup.9 is hydrogen, lower-alkyl or acyl; Y is --S(O).sub.m R.sup.10 or --NHet and, where X is --NR.sup.9 --, --S--, --SO-- or --SO.sub.2 --, also --N(R.sup.11).sub.2 or --OR.sup.12 ; R.sup.10 is lower-alkyl; R.sup.11 and R.sup.12 are hydrogen, lower-alkyl or acyl; --NHet is a 5-8 membered, saturated or unsaturated, monocyclic heterocycle attached via a N-atom; n is 2, 3 or 4 and m is 0, 1 or 2, are described. The compounds of formula I are useful as agents for the treatment of disorders such as neoplasms, dermatoses or ageing of the skin.
