A new protocol for the synthesis of tetracyclic nitrogen heteroarenes using cascade radical cyclisation has been developed. The key steps involve 5-exo vinyl radical cyclisation onto nitriles to yield intermediate iminyl radicals which cyclise onto an arene rings. Rings A-D of the anticancer alkaloids camptothecin, mappicine and nothapodytines A and B have been synthesised using this protocol.
一种利用级联自由基环化合成四环氮杂
芳烃的新方法已被开发出来。关键步骤涉及五元外
乙烯基自由基环化到腈类上,生成中间的亚
氨基自由基,这些自由基进一步环化到芳环上。抗癌
生物碱喜树碱、马普辛和诺塔波地汀A和B的环A-D就是通过这个方法合成的。