(Matrix presented) (+)-Sparteine The total synthesis of (+)-sparteine was accomplished from 2,5-norbornadione in 15 steps and 15.7% overall yield. The key steps were two ring-expansion reactions, one involving an intramolecular Schmidt reaction and one using a novel variant of the photo-Beckmann rearrangement.
As the starting material for the synthesis of sparteine derivatives, 5-oxosparteine (II) was synthesized. Condensation of Δ5-dehydrosparteine (IX) or Δ1(6)-dehydrosparteinium ion (VIII) and benzaldehyde gave 5-benzylidene-Δ1(6)-dehydrosparteinium ion (X) which was reduced to 5-benzylidenespartein (XI), and its oxidative cleave should have provied II but the objective was not attained. 5-Hydroximinosparteinium ion was obtained by the condensation of IX and nitrosyl chloride or VIII and ethyl nitrite, this sparteinium ion was reduced to 5-hydroximinosparteine (XIII), and its treatment with pyruvic acid gave the objective II. II has the same configuration as that of sparteine.
A Synthesis of Sparteine - ResearchGate
We hope that the increased availability of both enantiomers will break barriers to the use of Sparteine in synthesis and catalysis and reduce the cost of downstream specialty products that depend on Sparteine along their production.