Chemistry of pyrrolizinones. Part 1. Reactions of pyrrolizin-3-ones with electrophiles: synthesis of 3,8-didehydroheliotridin-5-one 1
作者:Hamish McNab、(the late) Craig Thornley
DOI:10.1039/b005620k
日期:——
The reaction of pyrrolizin-3-one 1 with dry hydrogen chloride gives the 1-chloro-1,2-dihydro derivative 8 (93%) by electrophilic addition. The halogen of 8 is readily displaced by O-nucleophiles to give 6, 9 or 10 in 87–100% yield, and this strategy has been employed in a short synthesis of the necine base didehydroheliotridin-5-one 4. Pyrrolizinone 1 can be brominated by N-bromosuccinimide in the
吡咯嗪3-one 1与干燥的反应氯化氢通过亲电加成得到1-氯-1,2-二氢衍生物8(93%)。这卤素的8可容易地通过移位ø -nucleophiles,得到6,9或10中87-100%的产率,并且该策略已经在necine基didehydroheliotridin -5-酮的合成短已经采用4。吡咯嗪酮1可以溴化N-溴琥珀酰亚胺在亲核试剂存在下给出20或21,或在自由基条件下得到2-溴吡咯烷酮22(55%)。维尔斯迈尔甲酰化的1得到的各种产品,包括5-formylpyrrolizinone 26(16%),但偶氮耦合只能在碱性条件下可以观察到,得到耦合丙烯酸甲酯31(46%)通过开环物种的阴离子30。