Conversion of 20-acetoxy-18-iodopregn-4-en-3-one 1 to the 18-iodosyl derivative by MCPBA resulted in a Wagner–Meerwein-type rearrangement with regioselective migration of the C13–C17 bond to give, in high yield, an abeo-pregnane in which C-18 was incorporated into ring D. The rearranged steroid was epoxidized in situ yielding a mixture of β and α 13,14-epoxides (3 and 4) which were characterized spectroscopically and by X-ray crystallography. When (20R)-20-iodopregn-4-en-3-one 9a was used as substrate, regioselective migration of the C16–C17 bond gave the D-homoandrostane with incorporation of C-20 into ring D in up to 95% yield. The 20S epimer 9b however, gave a mixture of substitution and rearrangement
products. The crystal structures of the deacetylated β-epoxide 3 (5), the methanolysis product of α-epoxide 4 (7) and 20-iodopregnanes 9a and 9b are reported.
通过 MCPBA 将 20-acetoxy-18-iodopregn-4-en-3-one 1 转化为 18-iodosyl 衍
生物,导致 Wagner-Meerwein 型重排,并伴随 C13-C17 键的区域选择性迁移,以高产率得到,一种 abeo-孕烷,其中 C-18 并入环 D。重排的类
固醇原位环氧化,产生 β 和 α 13,14-
环氧化物(3 和 4)的混合物,通过光谱和 X 射线晶体学对其进行了表征。当 (20R)-20-iodopregn-4-en-3-one 9a 用作底物时,C16-C17 键的区域选择性迁移产生 D-高
雄甾烷,其中 C-20 并入环 D,产率高达 95% 。然而,20S 差向异构体 9b 给出了取代和重排的混合物
产品。报道了脱乙酰基β-
环氧化物3 (5)、α-
环氧化物4 (7) 的
甲醇分解产物以及20-
碘孕烷9a 和9b 的晶体结构。