New cinchona alkaloids for the industrial chemist’s toolkit

The cinchona alkaloids quinine and cinchonidine (together with their pseudoenantiomers quinidine and cinchonine) are recognised as a priveleged class of compounds in asymmetric catalysis. A recent Angewandte minireview* has highlighted an emerging class of bifunctional phenolic (“desmethyl”) cinchona organocatalysts known as cupreine and cupreidine respectively:

The minireview highlights the application of these catalysts in Baylis-Hillman reactions, conjugate additions, electrophilic aminations and nitroaldol reactions.
The catalysts are available in one or two easy steps from commercially available alkaloids. Minimal catalyst loading is required in many cases, and the levels of chemo- regio- and enantio- control is in some cases unmatched by metal complexes or other organocatalysts.
Although not reported in the minireview, cupreine and cupreidine will no doubt be a new addition to the organic chemists collection of tools for the classical resolution of chiral acids by diastereomeric salt formation.
* T. Marcelli, J.H. van Maarseveen and H. Hiemstra, Angew. Chem. Int. Ed., 2006, 45, 7496-7504.


Peter Spargo