title: On reactions of steroidal 23-oxo and 23,24-epoxysapogenins with Lewis acids.
abstract: The reaction of 23-oxotigogenin acetate with TMSOTf in THF afforded the corresponding bisnorcholanic lactone in 60% yield. The analogous reactions carried out in dichloromethane or benzene gave the rearranged products--the isomeric spirostanic ketone (10-15%) and bisfuran (40-42%). Similar products were also obtained upon treatment of 23,24-epoxysapogenins with BF(3). The epoxides treated with TiCl(4) afforded mostly chlorohydrins and no rearranged products were detected.
authors.affiliation: Institute of Chemistry, University of Białystok, Piłsudskiego 11/4, 15-443 Białystok, Poland.
authors.forename: Izabella
authors.initials: I
authors.lastname: Jastrzebska
authors.forename: Leszek
authors.initials: L
authors.lastname: Siergiejczyk
authors.forename: Aneta M
authors.initials: AM
authors.lastname: Tomkiel
authors.forename: Zofia
authors.initials: Z
authors.lastname: Urbańczyk-Lipkowska
authors.forename: Dominik
authors.initials: D
authors.lastname: Wójcik
authors.forename: Jacek W
authors.initials: JW
authors.lastname: Morzycki
mesh_terms: D018360:Crystallography, X-Ray; D008698:Mesylates / Q000737:chemistry; D012502:Sapogenins / Q000737:chemistry*; D014297:Trimethylsilyl Compounds / Q000737:chemistry
chemical_list: C543893:23-oxotigogenin acetate; D008698:Mesylates; D012502:Sapogenins; D014297:Trimethylsilyl Compounds; C053353:trimethylsilyl trifluoromethanesulfonate