560119-47-3Relevant academic research and scientific papers
The First and Second Cinchona Rearrangement. Two Fundamental Transformations of Alkaloid Chemistry
Franz, M. Heiko,Roeper, Stefanie,Wartchow, Rudolf,Hoffmann
, p. 2983 - 2991 (2007/10/03)
Stereochemistry, products, and driving forces of the "first and second Cinchona rearrangement" have been investigated and a unified theory is presented. The first cage expansion affords [3.2.2]azabicyclic α-amino ether and is formulated via a configurationally stable bridgehead iminium ion and quasiequatorial nucleophilic attack. The second cage expansion affords β-functionalized [3.2.2]azabicycles. In this case a nonclassical nitrogen-bridged cation is postulated to account for retention of configuration and potential reversibility of the cage expansion. The second rearrangement is favored for the so-called cinch bases (6′-R = H) in trifluoroethanol. Stereoelectronic factors, electron demand at C9, ground state conformation, and solvent type are crucial in all cases. A two-step protocol for preparing 9-epi-configured Cinchona alkaloids from 9-nat precursors is described.
Preparation of enantiopure 1-azabicyclo[3.2.2]nonanes Functionalized at carbon C3, from cinchonine and cinchonidine. Stereoselective solvolysis and an easily enolizable ketone
Roeper, Stefanie,Franz, M. Heiko,Wartchow, Rudolf,Hoffmann, H. Martin R.
, p. 4944 - 4946 (2007/10/03)
Solvolysis of C9 mesylated cinchonidine 1-OMs and cinchonine 2-OMs in solvent MeOH, EtOH, and CF3CH2OH affords ring-expanded 1-azabicyclo[3.2.2]nonanes oxygenated at carbon C3 ("second Cinchona rearrangement"). The newly introduced s
