[reaction: see text]. The intramolecular [4 + 2]-cycloaddition of a 2-methylthio-5-amidofuran was used to create the azepinoindole skeleton present in the Stemona alkaloid stenine. The rearranged cycloadduct was converted to stenine (1) in 11 additional steps via a sequence that features a Crabtree catalyst directed hydrogenation (9-->10), iodolactonization (2-->11), and a Keck allylation (11-->12)
[反应:请参见文字]。使用2-甲
硫基5-
氨基
呋喃的分子内[4 + 2]-环加成反应,可生成存在于Smonona
生物碱Stenine中的氮杂
吲哚骨架。经过重排的环加合物在11个额外的步骤中通过一个以Crabtree催化剂为导向的氢化反应(9-> 10),
碘代内酯化反应(2-> 11)和Keck烯丙基化反应(11->)的顺序转化为斯坦丁(1) 12)。