Direct C(1) Hydroxylation of Vitamin D3 and Related Compounds

Article abstract of DOI:10.1021/jo01304a022

A direct synthesis of C(1) hydroxylated vitamin D analogues from the corresponding vitamin D precursors has been developed.Allylic oxidation of 3,5-cyclovitamin D derivatives, readily obtained from the buffered solvolysis of vitamin D tosylates, with selenium dioxide yields 1α-hydroxylated 3,5-cyclovitamin D compounds which are smoothly converted to the desired 1α-hydroxyvitamin D derivatives by acid-catalyzed cycloreversion.Application of this scheme to vitamin D₃ (1a), 25-hydroxyvitamin D₃ (1b), and vitamin D₂ (1c) affords the 1α-hydroxy products in ca.20 percent overall yield.