Author's Organization:New Drug Research Laboratories, Chugai Pharmaceutical Co., Ltd., New Drug Research Laboratories, Chugai Pharmaceutical Co., Ltd., New Drug Research Laboratories, Chugai Pharmaceutical Co., Ltd., New Drug Research Laboratories, Chugai Pharmaceutical Co., Ltd.,
The synthesis of two vitamin D3 analogues, 1α, 25-dihydroxy-20-oxa-21-norvitamin D3 (2) and 1α-hydroxy-20-oxa-21-norvitamin D3(3) from dehydroepiandrosterone (4) is described.