Ck. Sha et al., Synthesis of aza bicyclic enones via anionic cyclization: Application to the total synthesis of (-)-brunsvigine, ORG LETT, 3(14), 2001, pp. 2177-2179
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A general approach to the synthesis of aza bicyclic enones was developed vi
a a simple two-step annulation involving a Mitsunobu protocol and anionic c
yclization. According to this strategy the total synthesis of (-)-brunsvigi
ne was accomplished with 12% overall yield.