New chemistry of pyrrolizin-3-one: a concise route to 3,8-didehydroheliotridin-5-one
作者:Hamish McNab、Craig Thornley
DOI:10.1039/c39930001570
日期:——
1-Substituted 1,2-dihydropyrrolizin-3-ones can be obtained from pyrrolizin-3-one 2 by conjugate nucleophilic addition or electrophilic addition reactions; the 1-chloro compound 9 obtained by the latter method is used as a key intermediate in a six-step synthesis of the title compound 3 from 4-acetoxymethylpyridine-N-oxide.
In the title compound (the ester 2-formyl-3-pyrrolylmethyl acetate, C8H9NO3), hydrogen bonding between the N-H function in one molecule and the ester carbonyl O atom in a molecule related to the first by the 2(1) screw axis leads to the formation of zigzag chains.
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