Organocatalytic enantioselective hydrophosphonylation of ketimines using cinchona alkaloids and Na(2)CO(3) afforded products with high enantioselectivity. Both enantiomers of alpha-amino phosphonates can be prepared by using pseudoenantiomeric cinchona alkaloids. The catalyst loading of cinchona alkaloids can be reduced to 0.5 mol % without a significant loss of enantioselectivity.
Enantioselective Desymmetrization of meso-N-(Heteroarenesulfonyl)aziridines with TMSN3 Catalyzed by Chiral Lewis Acids. -Optimized reaction conditions are developed to give functionalized azides with moderate to high enantioselectivity. Product (IIa) represents a building block for the selective κ-opioid agonist U-50,488 (III). -(NAKAMURA*, S.; HAYASHI, M.; KAMADA, Y.; SASAKI, R.; HIRAMATSU, Y.; SHIBATA, N.; TORU, T.; Tetrahedron Lett. 51 (2010) 29, 3820-3823,
Alkaloids. -Organocatalytic enantioselective hydrophosphonylation of ketimines using commercially available cinchona alkaloids and Na2CO3 affords products with high enantioselectivity. Both enantiomers of α-amino phosphonates can be prepared by using pseudoenantiomeric cinchona alkaloids. The catalyst loading of cinchona alkaloids can be reduced to 0.5 mol% without a significant loss of enantioselectivity. -(NAKAMURA*, S.; HAYASHI, M.; HIRAMATSU, Y.; SHIBATA, N.; FUNAHASHI, Y.; TORU, T.; J.
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