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