Novel chiral hydrogen bond donor catalysts based on a 4,5-diaminoxanthene scaffold: application to enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes
Novelchiral hydrogen bond donor catalysts based on a 4,5-diamino-9,9′-dimethylxanthene skeleton were designed and synthesized. Among the phenylurea-amide hybrid molecules prepared from various natural/unnatural chiral amino acids, the phenylalanine-derived catalyst, and the proline-derived catalyst were successfully applied to enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes
Ephedrine- and Pseudoephedrine-Derived Thioureas in Asymmetric Michael Additions of Keto Esters and Diketones to Nitroalkenes
作者:Carsten Bolm、Angelika Flock、Anke Krebs
DOI:10.1055/s-0029-1219582
日期:2010.5
Ephedrine-derived bifunctional thioureas have been synthesized and applied as organocatalysts in Michael additions of 1,3-dicarbonyl compounds to nitroalkenes.
Asymmetric Michael Addition Mediated by Novel Cinchona Alkaloid-Derived Bifunctional Catalysts Containing Sulfonamides
作者:Jie Luo、Li-Wen Xu、Robyn Aik Siew Hay、Yixin Lu
DOI:10.1021/ol802486m
日期:2009.1.15
Novel cinchona alkaloid-derived bifunctional organocatalysts containing sulfonamide groups were utilized to promote Michael addition of bicyclic α-substituted β-ketoesters to nitroolefins. The desired Michael adducts with all-carbon quaternary centers were constructed in high yield and with excellent enantioselectivity, demonstrating the great potential of cinchona alkaloid-derived sulfonamides in
Synthesis of cinchona squaramide polymers by Yamamoto coupling polymerization and their application in asymmetric Michael reaction
作者:Sadia Afrin Chhanda、Shinichi Itsuno
DOI:10.1016/j.reactfunctpolym.2021.104913
日期:2021.7
chiral polymers were successfully utilized as polymeric catalysts in asymmetricMichael addition reactions. Good to excellent enantioselectivities were observed for different types of asymmetricMichaelreactions. Using the chiral homopolymer catalyst P4, almost perfect diastereoselectivity (>100:1) with 99% ee was obtained for the reaction between methyl 2-oxocyclopentanecarboxylate 25 and trans-β-nitrostyrene
Chiral Squaramide Derivatives are Excellent Hydrogen Bond Donor Catalysts
作者:Jeremiah P. Malerich、Koji Hagihara、Viresh H. Rawal
DOI:10.1021/ja805693p
日期:2008.11.5
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