title: Rearrangement of 23-oxospirostanes to the 22-oxo-23-spiroketal isomers promoted by Lewis acids--X-ray crystal structure of (23R,25S)-3beta-acetoxy-16beta,23:23,26-diepoxy-5beta-cholestan-22-one.
abstract: Both 25R and 25S 23-oxospirostanes undergo rearrangement to the 22-oxo-23-spiroketal isomers promoted by Lewis acids. An X-ray crystal structure analysis of the rearranged product of 23-oxosarsasapogenin acetate confirmed the R configuration at the new spiro carbon atom.
authors.affiliation: Department of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland.
authors.forename: Michał K
authors.initials: MK
authors.lastname: Cyrański
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Frelek
authors.forename: Izabella
authors.initials: I
authors.lastname: Jastrzebska
authors.forename: Jacek W
authors.initials: JW
authors.lastname: Morzycki
mesh_terms: D000143:Acids / Q000737:chemistry*; D000147:Acids, Heterocyclic; D002778:Cholestanones / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007536:Isomerism; D008968:Molecular Conformation; D013150:Spirostans / Q000737:chemistry*
chemical_list: C496312:(23R,25S)-3beta-acetoxy-16beta,23:23,26-diepoxy-5beta-cholestan-22-one; D000143:Acids; D000147:Acids, Heterocyclic; D002778:Cholestanones; D013150:Spirostans