Chiral squaramide derivatives are excellent hydrogen bond donor catalysts |
| |
Authors: | Malerich Jeremiah P Hagihara Koji Rawal Viresh H |
| |
Institution: | Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA. |
| |
Abstract: | Thioureas represent the dominant platform for hydrogen bond promoted asymmetric catalysts. A large number of reactions, reported in scores of publications, have been successfully promoted by chiral thioureas. The present paper reports the use of squaramides as a highly effective new scaffold for the development of chiral hydrogen bond donor catalysts. Squaramide catalysts are very simple to prepare. The (-)-cinchonine modified squaramide (5), easily prepared through a two-step process from methyl squarate, was shown to be an effective catalyst, even at catalyst loadings as low as 0.1 mol%, for the conjugate addition reactions of 1,3-dicarbonyl compounds to beta-nitrostyrenes. The addition products were obtained in high yields and excellent enantioselectivities. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|