Abstract: A method of treating metabolic bone diseases such as osteoporosis, as well as other disease states treatable with vitamin D compounds, comprises administering an effective amount of one or more modified vitamin D compound. The modified compound contains a typical vitamin D nucleus but with in vivo hydrolyzable groups at one or more of the 1, 3 and 25 carbon positions. The time of conversion of the modified compound to its active form, such as calcitriol, can be regulated to thus provide controlled release of the compound in vivo over time, by changing or modifying the hydrolyzable groups.

Abstract: The invention relates to a method for preparing vitamin D-related compounds and to certain intermediate compounds in such process. The intermediate compounds are characterized by an aldehyde or ester in the C-22 position in the side chain. The presence of such groups permit facile side chain additions for the preparation of vitamin D derivatives.

Abstract: The invention relates to a process for preparing 1-hydroxyvitamin D compounds by acid-catalyzed solvolysis of the corresponding 1-hydroxy-3,5-cyclovitamin D compound in an organic solvent medium whereby the free, non-acylated, 5,6-cis and 5,6-trans-1-hydroxylated vitamin D compounds are obtained in admixture.

Abstract: The invention relates to a process for separating 1.alpha.-hydroxyvitamin D compounds from their corresponding 1.alpha.-hydroxy-5,6-trans isomers in a mixture thereof by treating the mixture with a dienophile and then separating the resulting dienophil-adduct of the 1.alpha.-hydroxy-5,6-trans vitamin D isomer from the unreacted 1.alpha.-hydroxyvitamin D compound.