Studies of vitamin D (calciferol) and its analogs. 42. 3-Deoxy-3-thia-1. alpha., 25-dihydroxyvitamin D3 and its 1. beta.-epimer: synthesis and biological evaluation

AS Lee, AW Norman, WH Okamura

Index: Lee, Adam S.; Norman, Anthony W.; Okamura, William H. Journal of Organic Chemistry, 1992 , vol. 57, # 14 p. 3846 - 3854

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Citation Number: 25

Abstract

The syntheaea of 3-deoxy-3-thia-la, 25-dihydroxyvitamin D3 (Sa) and its@ epimer Sb have been achieved starting from CD-fragment 10 and the enantiomerically pure A-rings lla and llb prepared from thia 1, 3-diketone 13. For the preparation of lla and llb, the thia diketone 13 was converted in two steps to the trimethylsilyl enynone 18. In the most effective route, the latter was asymmetrically reduced using (R)-or (5')-oxazaborolidine 24 and 25 and ...