- On reactions of steroidal 23-oxo and 23,24-epoxysapogenins with Lewis acids.
On reactions of steroidal 23-oxo and 23,24-epoxysapogenins with Lewis acids.
Steroids (2009-05-26)
Izabella Jastrzebska, Leszek Siergiejczyk, Aneta M Tomkiel, Zofia Urbańczyk-Lipkowska, Dominik Wójcik, Jacek W Morzycki
PMID19463690
摘要
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.