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DOI: 10.1055/s-0030-1258780
Cinchona Alkaloid Squaramide Catalyzed Sulfa-Michael Addition
Contributor(s):Benjamin List, Anna LeeFudan University, Shanghai, P. R. of China
A Bifunctional Cinchona Alkaloid-Squaramide Catalyst for the Highly Enantioselective Conjugate Addition of Thiols to trans-Chalcones
Adv. Synth. Catal. 2010, 352: 2137-2141
Publication History
Publication Date:
21 October 2010 (online)
Key words
bifunctional organocatalysis - squaramides - sulfa-Michael addition
Significance
An efficient cinchona alkaloid squaramide catalyzed asymmetric sulfa-Michael conjugate addition of thiols to trans-chalcones is described. Chen and co-workers applied the cinchona squaramide catalyst developed by Rawal’s group (J. P. Malerich, K. Hagihara, V. H. Rawal J. Am. Chem. Soc. 2008, 130, 14416) to sulfa-Michael reactions and the products were obtained in moderate to good yields as well as moderate to high enantioselectivities under mild reaction conditions.
Comment
Recently, Melchiorre and co-workers developed an efficient sulfa-Michael addition (SMA) to α,β-unsaturated ketones using cinchona alkaloid catalyst salts (Adv. Synth. Catal. 2008, 350, 49). Although there are several examples of organocatalytic sulfa-Michael reactions (P. Suresh, K. Pitchumani Tetrahedron: Asymmetry 2008, 19, 2037; H. Li, L. Zu, J. Wang, W. Wang Tetrahedron Lett. 2006, 47, 3145), these catalytic systems still have limitations, such as a relatively high catalyst loading and narrow substrate scope. Here, Chen and colleagues present a more effective catalyst system for the SMA.