substructure of Strychnos alkaloids and a Nb-(formylmethyl) substituent protected as an oxime or hydrazone derivative, have been prepared by nucleophilic addition of the enolate of indoleacetic ester 1 to pyridinium salts 2b–d followed by acid cyclization. The same one-pot, two-step sequence allowed the preparation of tetracycle 3f, which incorporates an α-methoxyacrylate chain at the piperidine β-position
Tetracycles 3B-d ,具有的AB
CD环子
马钱子碱和一个Ñ b - (甲酰基甲基)取代基保护为
肟或腙衍
生物,制备通过亲核加成的
吲哚酯的烯醇化物的1到
吡啶鎓盐2B-d随后通过酸环化。相同的一锅两步程序允许制备四环3f,该四环3f在
哌啶β位置掺入了α-甲氧基
丙烯酸酯链。