Fremgangsmåde til at fremstille 16-dehydro vitamin D forbindelser

The invention relates to a new method of preparing 16-dehydro vitamin D compounds having formula I wherein: R has the epi-configuration or the normal configuration and represents straight or branched C1-6-alkyl, C2-6-alkenyl, C3-6-cycloalkyl, or an aromatic group optionally substituted with halogen, C1-3-alkyl or alkoxy, Z is a saturated or unsaturated straight hydrocarbon group or oxahydrocarbon group containing 3-6 C-atoms which may be substituted with OH, F, alkyl (C1-3) or cycloalkyl (C3-5), R1 is hydrogen or an hydroxy protecting group, R2 is hydrogen or hydroxy, and A and B represent hydrogen or methyl, or together form the methylene group, to the new compounds having this formula and to new intermediates obtainable according to this process.