title: Alpha-hydroxylation at C-15 and C-16 in cholesterol: synthesis of (25R)-5alpha-cholesta-3beta,15alpha,26-triol and (25R)-5alpha-cholesta-3beta,16alpha,26-triol from diosgenin.
abstract: [reaction: see text] (25R)-5alpha-cholesta-3beta,16alpha,26-triol 7b and (25R)-5alpha-cholesta-3beta,15alpha,26-triol 10b were synthesized, via (25R)-5alpha-cholesta-3beta,16beta,26-triol 5a, from diosgenin 3 in 52% yield over six steps and 47% yield over eight steps, respectively. An efficient method for inversion of a C-16beta hydroxyl to the C-16alpha position and a short method for transposition of a C-16beta hydroxyl to the C-15alpha position via the unexpected beta-reduction of a C-15 ketone in a steroid are reported.
authors.affiliation: Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122-2585, USA. john.r.williams@temple.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Williams
authors.forename: Hua
authors.initials: H
authors.lastname: Gong
authors.forename: Nathan
authors.initials: N
authors.lastname: Hoff
authors.forename: Olaoluwa I
authors.initials: OI
authors.lastname: Olubodun
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Carroll
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004144:Diosgenin / Q000138:chemical synthesis / Q000737:chemistry*; D006888:Hydroxycholesterols; D006900:Hydroxylation; D008958:Models, Molecular; D008968:Molecular Conformation
chemical_list: C496881:(25R)-5alpha-cholesta-3beta,16alpha,26-triol; D006888:Hydroxycholesterols; D002784:Cholesterol; D004144:Diosgenin