Synthesis of Active Forms of Vitamin D. VIII. Synthesis of [24R] -and [24S] -1α, 24, 25-Trihydroxyvitamin D₃

Abstract

24ξ, 25-Dihydroxycholesterol was converted, through 1, 4, 6-trien-3-one and its 1α, 2α-epoxide, into 1α, 24ξ, 25-trihydroxycholesterol. After resolution of C-24 epimers and determining their configurations, both isomers were led to [24R]- and [24S]-1α, 24, 25-trihydroxyvitamin D₃ by bromination, dehydrobromination and ultraviolet-irradiation.