METHOD OF PREPARING VITAMIN D _AND VITAMIN D _OR ACTIVATED VITAMIN D _AND ACTIVATED VITAMIN D _OR DERIVATIVES THEREFROM

摘要

There is provided a method with which vitamin D2, vitamin D3, activated type vitamin D2, activated type vitamin D3 and their derivatives are prepared from 7, 8dihyroxy vitamin D2, D3 or any of their derivatives by means of a reducing elimination technique involving as cyclic orthoester of a 7,8-dihydroxy compound or a thiocarbonate compound as an intermediate compound or an elimination technique utilizing a reducing metal such as titanium. The method according to the invention ensures a practical and simple synthetic process and a high yeild as compared with any existing methods for manufacturing these chemicals.