| 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 7,8 -dihyroxy 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.
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