Process for the preparation of active-type vitamin D3 compounds and of the cholesta-5,7-diene precursors, and products so obtained
申请人:TEIJIN LIMITED
公开号:EP0028484A1
公开(公告)日:1981-05-13
The present invention relates to a novel process for the preparation of active-type vitamin D3 compounds and their intermediates. In accordance with the present invention, a large amount of an active-type vitamin D3 compound, for example 1α-hydroxycholecalciferol, 1α,25-dihydrox- ycholecalciferol and the like, is efficiently prepared with high industrial advantage by a novel process which comprises (i) reacting hydroxycholesta-5-enes having the hydroxyl groups protected with lower alkoxycarbonyl groups as a starting material with an allylic brominating agent and a dehydrobrominating agent to prepare the corresponding hydroxycholesta-5,7-dienes, (ii) exposing the hydroxycholesta-5,7-dienes to ultraviolet irradiation or to a combination of the irradiation with thermal isomerization to obtain a mixture of the unreacted hydroxycholesta-5,7-dienes and previtamin D3 compounds or a mixture of the unreacted hydroxycholesta-5,7-dienes and the protected active-type vitamin D, compounds, (iii) separating the mixture into the unreacted hydroxycholesta-5,7-dienes and previtamin D3 compounds or the protected active-type vitamin D3 compounds, (iv) recycling the unreacted hydroxycholesta-5,7-dienes for reuse and (v) thermally isomerizing the remaining compounds and/or splitting off the protective groups. The process of the invention is of very high industrial value, capable of simple operation and adaptable to large scale commercial production.
Process for the preparation of active-type vitamin D.sub.3 compounds
申请人:Teijin Limited
公开号:US04388243A1
公开(公告)日:1983-06-14
The present invention relates to a novel process for the preparation of active-type vitamin D.sub.3 compounds and their intermediates. In accordance with the present invention, a large amount of an active-type vitamin D.sub.3 compounds, for example 1.alpha.-hydroxycholecalciferol, 1.alpha.,25-dihydroxycholecalciferol and the like, is efficiently prepared with high industrial advantages by a novel processes, which comprises (i) reacting hydroxycholesta-5-enes having the hydroxyl groups protected with lower alkoxycarbonyl group as a starting material with allylic brominating agent and dehydrobrominating agent to prepare the corresponding hydroxycholesta-5,7-dienes, (ii) exposing the hydroxycholesta-5,7-dienes to ultraviolet irradiation or to a combination of the irradiation with thermal isomerization to obtain a mixture of the unreacted hydroxycholesta-5,7-dienes and previtamin D.sub.3 compounds or a mixture of the unreacted hydroxycholesta-5,7-dienes and the protected active-type vitamin D.sub.3 compounds, (iii) separating the mixture into the unreacted hydroxycholesta-5,7-dienes and previtamin D.sub.3 compounds or the protected active-type vitamin D.sub.3 compounds, (iv) recycling the unreacted hydroxycholesta-5,7-dienes as reuse and (v) thermally isomerizing the remaining compounds and/or splitting off the protective groups. The process for the preparation of active-type vitamin D.sub.3 compounds, in the present invention, is of very high industrial value, capable of carrying out by simple operation and adaptable to large scale commercial production.