The Effect of Carbonyl on the Isomerization of Galanthan Ring System and Total Synthesis of (±)-β-lycorane via a Double Michael Addition Approach

Lycorine-type alkaloids are privileged structures in the drug development due to its attractive biological activities. In this paper, the carbonyl on the C ring was proved to have played a critical role on the stereoselectivity during the synthetic process, and the galanthan skeleton with cis-B/C ring is more thermodynamic stable in its presence. Furthermore, a total synthesis of (±)-β-lycorane was successfully completed by employing the Michael addition reaction to construct the galanthan skeleton with trans-B/C ring. This system might be applied to other structural types with similar stereochemistry setting.