On reactions of steroidal 23-oxo and 23,24-epoxysapogenins with Lewis acids.
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.
Jastrzebska
Izabella
I
Institute of Chemistry, University of Białystok, Piłsudskiego 11/4, 15-443 Białystok, Poland.
Siergiejczyk
Leszek
L
Tomkiel
Aneta M
AM
Urbańczyk-Lipkowska
Zofia
Z
Wójcik
Dominik
D
Morzycki
Jacek W
JW
D018360:Crystallography, X-Ray; D008698:Mesylates / Q000737:chemistry; D012502:Sapogenins / Q000737:chemistry*; D014297:Trimethylsilyl Compounds / Q000737:chemistry
C543893:23-oxotigogenin acetate; D008698:Mesylates; D012502:Sapogenins; D014297:Trimethylsilyl Compounds; C053353:trimethylsilyl trifluoromethanesulfonate