Compounds of formula ##STR1## wherein Q is a --CH.sub.2 --, --CH.dbd.CH-- or --C.dbd.C--; U is a C.sub.1 -C.sub.6 alkylene; R.sup.1 is hydrogen, a C.sub.1 -C.sub.4 alkyl or YR' in which Y stands for the radicals --SO-- or --SO.sub.2 -- and R' stands for a C.sub.1 -C.sub.4 alkyl; R.sup.2 and R.sup.3 are independently hydrogen or C.sub.1 -C.sub.4 alkyl, and additionally R.sup.2 and R.sup.3, when taken together with the starred carbon atom, may form a C.sub.3 -C.sub.6 carbocyclic ring; Z is hydrogen or hydroxy; and derivatives thereof. The compounds show antiinflammatory and immunomodulating effects as well as strong activity in inducing differentiation and inhibiting undesirable proliferation of certain cells. The compounds are prepared by adding an anion R.sup.- to 1(S),1(R)-bis-(tert-butyldimethylsilyl-oxy)-9,10-secopregna-5(E),7(E),10(19)-triene-20-one and the resulting compound is alkylated or acylated with R.sup.1 X.sup.1 where X.sup.1 is a leaving group followed by triplet-sensitized photoisomerization and deprotection to give the compound of formula I.