Convenient synthesis of 1α,25-dihydroxyvitamin D3 from vitamin D2

Article abstract of DOI:10.1246/bcsj.67.2494

(1S,6R)-1-Acetoxy-6-(1,3-benzodithiol-2-yloxy)-3,5-cyclovitamin D₂ (7) was synthesized from vitamin D₂ by five steps. The new compound 7 was ozonized regioselectively and subsequently reduced, leading to (7E)-(1S,3S,5R,6R)-1-acetoxy-6-(1,3-benzodithiol-2-yloxy)-3,5-cyclo-9, 10-seco-23,24-dinor-7,10(19)-choladien-22-ol (11). The alcohol 11 obtained as a key intermediate was tosylated, iodinated, and coupled with 2-methyl-4-phenylsulfonyl-2-(tetrahydropyranyloxy)butane to give (1S,6R)-1-hydroxy-6-(1,3-benzodithiol-2-yloxy)-23-phenylsulfonyl-25-te trahydropyranyloxy-3,5-cyclovitamin D₃ (16). By desulfonylation and hydrolysis of the compound 16 1α,25-dihydroxyvitamin D₃ was obtained selectively.