20-position modified pharmaceutically active vitamin D series compounds

A vitamin D compound of the formula ##STR51## in which Y means a hydrogen atom, an alkanoyl group of 1 to 9 carbon atoms, or an aroyl group, wherein each Y is chosen independently;

• Z means a hydrogen atom, a hydroxyl group or an alkanoyloxy group of 1 to 9 carbon atoms,
• X means a hydrogen atom or both X's together mean an exocyclic methylene group,
• R.sub.1 and R.sub.2 together mean a methylene group or together with carbon atom 20 form a cyclopropyl unit,
• R.sub.3 means a linear or branched alkyl group of 1 to 5 carbon atoms or a trifluoromethyl group, or the two R.sub.3 group together with carbon atom 25 form a cyclopropyl or cyclopentyl ring;
• L means the grouping ##STR52## in which A represents an oxygen atom, and B represents an alkylene group --(CH.sub.2).sub.n --, in which n=1, 2, 3, 4, 5 or 6, or
• L means grouping ##STR53## in which D represents a direct bond, a methylene bridge or a 1,2-ethenediyl bridge (E-double bond) between carbon atoms 20 and 22, E and F respectively represent a hydrogen atom, or together a second bond (E-double bond), and
• G represents a direct bond or an alkylene group --(CH.sub.2).sub.n --, in which n=1, 2, 3, 4, 5 or 6 or a corresponding alkylene group in which a methylene group is replaced by an oxygen atom.