Lou, S., Dai, P., Schaus, S.E., Asymmetric Mannich Reaction of Dicarbonyl Compounds with α-Amido Sulfones Catalyzed by Cinchona Alkaloids and Synthesis of Chiral Dihydropyrimidones, J. Org. Chem, 2007, 72, 9998-10008
link to the article [1]
Links:
[1] http://pubs.acs.org/cgi-bin/abstract.cgi/joceah/2007/72/i26/abs/jo701777g.html