Synfacts 2011(9): 0982-0982  
DOI: 10.1055/s-0030-1260904
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Catalytic Asymmetric Conjugate Addition of Pyrazolin-5-ones

Contributor(s): Hisashi Yamamoto, Patrick Brady
Z. Wang, Z. Yang, D. Chen, X. Liu, L. Lin, X. Feng*
Sichuan University, Chengdu, P. R. of China
Further Information

Publication History

Publication Date:
19 August 2011 (online)


This conjugate addition process is catalyzed by a combination of a Lewis acid and a chiral N,N′-dioxide ligand. The highly enantio-­enriched product, which is a pyrazolone derivative, bears contiguous tertiary and quaternary stereocenters. Remarkably, changing the Lewis acid and the solvent results in a switch in enantioselectivity. These inverse effects between Sc and Y may also be observed in other asymmetric reactions.