Vitamin D analogues

A compound of the formula I ##STR6## in which formula n is an integer from 1-7;

• and R.sup.1 and R.sup.2, which may be the same or different, stand for hydrogen, or straight or branched, saturated or unsaturated C.sub.1 -C.sub.7 -alkyl;
• with the provisos that when n=1, R.sup.1 and R.sup.2 cannot simultaneously be hydrogen, nor can R.sup.1 and R.sup.2 simultaneously be an alkyl group independently chosen from methyl, ethyl and normal-propyl, and when n=2, R.sup.1 and R.sup.2 cannot simultaneously be methyl;
• or C.sub.3 -C.sub.8 -cyclo-alkyl, or, taken together with the carbon (starred in formula I) bearing the hydroxyl group, R.sup.1 and R.sup.2 can form a saturated or unsaturated C.sub.3 -C.sub.9 carbocyclic ring;
• and R.sup.3 and R.sup.4 represent either both hydrogen, or when taken together constitute a bond, such double bond (either in the Z or E configuration) connecting carbons numbered 22 and 23;
• and derivatives of the compounds of formula I in which one or more hydroxy groups have been transformed into -O-acyl or -O-glycosyl or phosphate ester groups, such masked groups being hydrolyzable in vivo, or derivatives of the compounds of formula I in which the hydroxyl group at the starred carbon atom is lacking, these compounds being converted to active compounds of formula I by enzymatic hydroxylation after administration.