Bismuth(III) triflate-catalyzed rearrangement of 16α,17α-epoxy-20-oxosteroids. Synthesis and structural elucidation of new 16α-substituted 17α-alkyl-17β-methyl-Δ13-18-norsteroids
作者:Rui M.A. Pinto、Jorge A.R. Salvador、Christophe Le Roux、Rui A. Carvalho、Ana Matos Beja、José A. Paixão
DOI:10.1016/j.tet.2009.05.043
日期:2009.8
reagents, the reaction selectively affords the corresponding 16α-acyl rearranged products. The chemoselective rearrangement of 5β,6β;16α,17α-diepoxy-20-oxopregnan-3β-yl acetate to afford a ‘backbone’ rearranged product bearing the 16α,17α-epoxide group is also reported. Some mechanistic considerations are provided. All rearranged products were the subject of comprehensive structural elucidation, by
据报道,三氟甲磺酸铋(III)用于重排16α,17α-环氧-20-氧类固醇。真正的催化条件下发生反应,得到新颖的17α -烷基- 17β甲基Δ 13 -18-也不轴承产品不同öC 16上的含取代基。当在不存在酰化剂的情况下进行反应时,获得异构体16α-和16β-羟基衍生物的混合物,而当在此类试剂的存在下进行时,反应选择性地提供相应的16α-酰基重排产物。还报道了5β,6β;16α,17α-双环氧-20-氧杂戊烷-3β-乙酸乙烯酯的化学选择性重排,以提供带有16α,17α-环氧基团的“骨架”重排产物。提供了一些机械方面的考虑。通过使用X射线晶体学和2D NMR,对所有重排产物进行了全面的结构阐明。