The intermolecular [3 + 2] annulation of azomethine ylides with 2(2-nitrophenyl)acrylate dienophiles followed by reductive heterocyclization affords the spiro(indole-pyrrolidine) ring system. Hence, this enable us to accomplish a concise and highly enantioselective synthesis of (-)-horsfiline 1, based on chiral auxiliary-directed pi-face discrimination in the 1,3-dipolar cycloaddition of (1S,2R)-2
偶氮甲
亚胺的分子间[3 + 2]与2(2-
硝基苯基)
丙烯酸二烯酯的环化反应,然后进行还原性杂环化作用,得到螺环(
吲哚-
吡咯烷)环。因此,这使我们能够基于(1S,2R)-2-苯基-的1,3-偶极环加成中的手性辅助定向pi面识别,完成简明且高度对映选择性的(-)-horsfiline 1合成。 1-环己酯4f与
N-甲基甲亚胺叶立德。