On reactions of steroidal 23-oxo and 23,24-epoxysapogenins with Lewis acids

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• 作者：Izabella Jastrzę ; bska ; Leszek Siergiejczyk ; Aneta M. Tomkiel ; Zofia Urbań ; czyk-Lipkowska ; Dominik Wó ; jcik ; Jacek W. Morzycki
• 关键词：Rearrangements ; Chlorohydrins ; Spirostanes
• 刊名：Steroids
• 出版年：2009
• 出版时间：11 August 2009
• 年：2009
• 卷：74
• 期：8
• 页码：675-683
• 全文大小：872 K

文摘

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 BF₃. The epoxides treated with TiCl₄ afforded mostly chlorohydrins and no rearranged products were detected.