Abstract: A compound of the formula I: in which P is hydrogen or alkyl; Y and Y′ are each hydrogen or, when taken together, represent a group ═CH2; W and W′ are each hydrogen; X is selected from the group consisting of a hydroxyalkyl, a hydroxyalkoxy, an alkoxy optionally comprising an epoxide function, a hydroxyalkene, a hydroxyalkadiene, a hydroxyalkyne and isomeric forms thereof; and a) either R1 and R3 or R′3 form a saturated 5- or 6-membered carbocyclic ring and R2, R′2, R3 or R′3, R4, R′4, R5 and R′5 are each independently hydrogen or alkyl; or b) R2 or R′2 and R4 or R′4 form a saturated 5- or 6-membered carbocyclic ring, and R1, R2 or R′2, R3, R′3, R4 or R′4, R5 and R′5 are each independently hydrogen or alkyl; or c) R3 or R′3 and R5 or R′5 form a saturated or unsaturated 5- or 6-membered carbocyclic ring, and R1, R2, R′2, R3 or R′3, R4, R′4, and R5 or R′5 are each indep

Abstract: The present invention relates to analogues of vitamin D, which lack the combined presence of the trans-fused six-membered C-ring and of five-membered D-ring, but still possess a central part consisting of a substituted chain of five atoms, atoms which correspond to positions 8, 14, 13, 17 and 20 of vitamin D, and at the ends of which are connected, at position 20 a structural moiety representing part of the side-chain of vitamin D or of an analogue of vitamin D, and at position 8 the .DELTA.(5,7)-diene moiety connected to the A-ring of the active 1-alpha-hydroxy metabolite or of an established vitamin D analogue, to their preparation process, to preparation intermediates, to pharmaceutical preparations comprising these compounds and to their use in medicine.