3189-43-3Relevant articles and documents
Understanding "on-water" catalysis of organic reactions. Effects of H+ and Li+ ions in the aqueous phase and nonreacting competitor H-bond acceptors in the organic phase: On H2O versus on D2O for Huisgen cycloadditions
Butler, Richard N.,Coyne, Anthony G.
, p. 1809 - 1817 (2015)
For a typical Huisgen cycloaddition, carried out on water, the behavior of water molecules at the oil-water interface depended on the properties of the reactants. With weakly basic reactants, a small quantity of added H+ (HClO4, 0.0001-0.01 M) present in the aqueous phase had negligible effects, but larger quantities of H+ (HClO4, 0.1-3.0 M) increased the catalytic effect and caused protons to cross the water-organic interface and affect the products. Added Li+ ions (LiClO4, 0.1-3.0 M) had no effect for on-water reactions but enhanced the rates and endo products for in-water reactions. For these cycloaddition reactions, the product endo:exo ratios, when compared to those in organic solvents, can be used to distinguish between the on-water and in-water modes. Comparisons of organic reactions on H2O and on D2O indicate that on-water catalysis ranges from weak to strong trans-phase H-bonding for reactants with basic pKa a > ca. 2 (pKa of conjugate acid). Water shows a chameleon-type response to organic molecules at hydrophobic surfaces.
Cu(I)-Catalyzed Highly Enantioselective [3 + 3] Cycloaddition between Two Different 1,3-Dipoles, Phthalazinium Dicyanomethanides and Iminoester-Derived Azomethine Ylides
Yuan, Chunhao,Liu, Honglei,Gao, Zhenzhen,Zhou, Leijie,Feng, Yalin,Xiao, Yumei,Guo, Hongchao
supporting information, p. 26 - 29 (2015/07/28)
(Chemical Equation Presented). The Cu(I)-catalyzed highly enantioselective [3 + 3] cycloaddition between two different 1,3-dipoles, phthalazinium dicyanomethanides and iminoester-derived azomethine ylides, has been achieved under mild reaction conditions, providing novel chiral heterocyclic compounds, 2,3,4,11b-tetrahydro-1H-pyrazino[2,1-a]phthalazine derivatives, in high yields with excellent diastereo- and enantioselectivies (up to 99% yield, 99% ee, >20:1 dr).
Effect of electron-withdrawing substituents on the epoxide ring: An experimental and theoretical electron density analysis of a series of epoxide derivatives
Grabowsky, Simon,Schirmeister, Tanja,Paulmann, Carsten,Pfeuffer, Thomas,Luger, Peter
experimental part, p. 1305 - 1318 (2011/04/23)
A series of acceptor-substituted epoxide derivatives is scrutinized by means of experimental and theoretical electron-density investigations. Due to the possibility of nucleophilic ring-opening, the epoxide ring is not only a very useful functional group in organic synthesis, but acceptor-substituted epoxides are valuable building blocks for the design of protease inhibitors. Therefore, the electron-density analysis in this work focuses on two main aspects that can contribute to rational drug design: (i) the quantification of the electron-withdrawing substituent effects on the epoxide ring and (ii) the intermolecular interactions involving the epoxide ring in combination with different substituents. It can be shown that the electron-withdrawing properties of the substituents cause an elongation of the C-C bonds in the epoxide rings and the loss of electron density can be measured by an analysis of critical points, atomic charges, and the source function. The different strengths of the substituents are reflected in these properties. Covalent and electrostatic contributions to the intermolecular interactions and thus the lattice energies are depicted on different molecular surfaces.(Figure Presented)
