title: Constructing 24(23→22)-abeo-Cholestane from Tigogenin in a 20(22→23)-abeo-Way via a PhI(OAc)2-mediated Favorskii Rearrangement.
abstract: Transforming tigogenin, a steroidal sapogenin, to a 24(23→22)-abeo-cholestane, which is an unusual structural feature shared by the aglycons of saundersiosides and candicanoside A, is described. The spiroketal of tigogenin was unfolded and the resulting C22-ketone was subjected to Favorskii rearrangement mediated by PhI(OAc)2/KOH/MeOH to squeeze out the C22 from the side chain, thus reaching the 24(23→22)-abeo-cholestane structure.
authors.affiliation: CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.
authors.forename: Xiao-Ling
authors.initials: XL
authors.lastname: Jiang
authors.affiliation: CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.
authors.forename: Yong
authors.identifier: 0000-0002-7887-3050
authors.initials: Y
authors.lastname: Shi
authors.affiliation: CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.
authors.forename: Wei-Sheng
authors.initials: WS
authors.lastname: Tian