Enantioselective bromolactonization by using an amino-urea catalyst to generate the important bromo-containing 3,4-dihydroisocoumarins is described. Excellent yields and good enantioselectivities could be achieved for various 3,4-dihydroisocoumarin compounds.
Asymmetric chroman synthesis via an intramolecular oxy-Michael addition by bifunctional organocatalysts
作者:Ryota Miyaji、Keisuke Asano、Seijiro Matsubara
DOI:10.1039/c3ob41938j
日期:——
organocatalysts facilitate the catalytic asymmetric synthesis of chroman derivatives via an intramolecular oxy-Michael addition reaction. Phenol derivatives bearing an easily available (E)-α,β-unsaturated ketone or a thioester moiety are useful substrates for the title transformation. This method represents a facile synthesis of various optically active 2-substituted chromans in high yield.
Highly Enantioselective Decarboxylative Protonation of α-Aminomalonates Mediated by Thiourea <i>Cinchona</i> Alkaloid Derivatives: Access to Both Enantiomers of Cyclic and Acyclic α-Aminoacids
Thiourea derived cinchona alkaloids promote the asymmetric decarboxylative protonation of cyclic, acyclic, or bicyclic alpha-aminomalonate hemiesters under mild and metal-free conditions to afford enantioenriched aminoesters in high yields and enantioselectivities up to 93%. Both enantiomers of the aminoesters have been synthesized with the same selectivity when using organic base 3 and its pseudoenantiomer
Enantio- and diastereoselective Michael additions of C-succinimidyl esters to nitro olefins using cinchonine-derived bifunctional organocatalysts
作者:Pavol Jakubec、Dane M. Cockfield、Peter S. Hynes、Ed Cleator、Darren J. Dixon
DOI:10.1016/j.tetasy.2011.06.002
日期:2011.6
A novel bifunctional organocatalytic Michaeladdition of a succinimide-derived pronucleophile to nitroolefins is described. The use of a range of nitroolefins afforded Michael adducts containing contiguous quaternary and tertiary stereogenic centres in high enantioselectivities and moderate diastereoselectivities.
Asymmetric Indoline Synthesis via Intramolecular Aza-Michael Addition Mediated by Bifunctional Organocatalysts
作者:Ryota Miyaji、Keisuke Asano、Seijiro Matsubara
DOI:10.1021/ol401538b
日期:2013.7.19
A novel method for the asymmetric synthesis of 2-substituted indolines, employing bifunctional amino(thio)urea catalysts, was developed. The reaction proceeded via an intramolecular aza-Michael addition mediated by activation through hydrogen bonding. The catalytic process was shown to be highly versatile and applicable to a wide range of substrates due to the flexible catalytic mechanism utilizing a noncovalent interaction.