926309-16-2Relevant academic research and scientific papers
Correlation between the Selectivity and the Structure of an Asymmetric Catalyst Built on a Chirally Amplified Supramolecular Helical Scaffold
Desmarchelier, Alaric,Caumes, Xavier,Raynal, Matthieu,Vidal-Ferran, Anton,Van Leeuwen, Piet W. N. M.,Bouteiller, Laurent
supporting information, p. 4908 - 4916 (2016/05/10)
For the first time, supramolecular helical rods composed of an achiral metal complex and a complementary enantiopure monomer provided a good level of enantioinduction in asymmetric catalysis. Mixtures containing an achiral ligand monomer (BTAPPh2, 2 mol %) and an enantiopure ligand-free comonomer (ester BTA, 2.5 mol %), both possessing a complementary benzene-1,3,5-tricarboxamide (BTA) central unit, were investigated in combination with [Rh(cod)2]BArF (1 mol %) in the asymmetric hydrogenation of dimethyl itaconate. Notably, efficient chirality transfer occurs within the hydrogen-bonded coassemblies formed by BTA Ile and the intrinsically achiral catalytic rhodium catalyst, providing the hydrogenation product with up to 85% ee. The effect of the relative content of BTA Ile as compared to the ligand was investigated. The amount of chiral comonomer can be decreased down to one-fourth of that of the ligand without deteriorating the enantioselectivity of the reaction, while the enantioselectivity decreases for mixtures containing high amounts of BTA Ile. The nonlinear relationship between the amount of chiral comonomer and the enantioselectivity indicates that chirality amplification effects are at work in this catalytic system. Also, right-handed helical rods are formed upon co-assembly of the achiral rhodium complex of BTAPPh2 and the enantiopure comonomer BTA Ile as confirmed by various spectroscopic and scattering techniques. Remarkably, the major enantiomer and the selectivity of the catalytic reaction are related to the handedness and the net helicity of the coassemblies, respectively. Further development of this class of catalysts built on chirally amplified helical scaffolds should contribute to the design of asymmetric catalysts operating with low amounts of chiral entities.
Efficient microwave-assisted synthesis of ionic esterified amino acids
Ceron-Camacho, Ricardo,Aburto, Jorge,Montiel, Luisa E.,Flores, Eugenio A.,Cuellar, Frisia,Martinez-Palou, Rafael
experimental part, p. 8733 - 8744 (2011/12/02)
In this work, an efficient microwave-assisted methodology for the esterification of unprotected α-amino acids is described. Ionic esterified amino acids were synthesized in satisfactory yields in a facile one-pot solventless protocol from unprotected amin
Stable supramolecular helical structure of C6-symmetric hydrogen-bonded hexakis(phenylethynyl)benzene derivatives with amino acid pendant groups and their unique fluorescence properties
Sakajiri, Koichi,Sugisaki, Takeshi,Moriya, Keiichi
supporting information; experimental part, p. 3447 - 3449 (2009/02/05)
A highly stable supramolecular helical structure was formed by the self-assembly of novel C6-symmetric hydrogen-bonded discotic molecules, hexakis(phenylethynyl)benzene derivatives with chiral alanine parts, and exhibited orange excimer emission with a large Stokes shift. The Royal Society of Chemistry.
Antiviral phosphoramidates
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Page/Page column 36, (2008/06/13)
The invention provides novel nucleoside compounds of formula I wherein R1, R2a, R2b, R3, R4, R5, R6, R8a, R9 and R10 are as defined herein which are useful for the treatment of Hepatitis C Virus (HCV) mediated diseases. The invention further provides methods for treatment or prophylaxis of HCV mediated diseases with compounds of formula I and pharmaceutical compositions comprising these compounds,
