3149-62-0Relevant articles and documents
Calorimetric measurement of the CH/π interaction involved in the molecular recognition of saccharides by aromatic compounds
Bautista-Ibanez, Lorena,Ramirez-Gualito, Karla,Quiroz-Garcia, Beatriz,Rojas-Aguilar, Aaron,Cuevas, Gabriel
, p. 849 - 857 (2008)
(Chemical Equation Presented) Can a benzene molecule differentiate between two isomeric carbohydrates? It is generally accepted that two factors govern molecular recognition: complementarity and preorganization. Preorganization requires the presence of cavities for positioning the host's groups of complementary nature to those of the guest. This study shows that, in fact, groups should be complementary to recognize each other (for the case presented here, it is controlled by the CH/π interaction) but preorganization is not essential. Since weak interactions have their origin in dispersion forces, they also have impact on the enthalpic term of the free energy, so it was considered that their participation can be demonstrated by measuring the energy involved. For recognition to happen, two conditions must be satisfied: specificity and associated stabilizing energy. In this study we evaluated the heat of dissolution of different carbohydrates such as methyl 2,3,4,6-tetra-O-methyl- α-D-mannopyranoside and methyl 2,3,4,6-tetra-O-methyl-β-D- galactopyranoside using different aromatic solvents. The solvation enthalpies in benzene were -78.8 ± 3.9 and -88.7 ± 5.5 kJ mol-1 for each carbohydrate, respectively; and these values yielded a CH/π energy of interaction of 9.9 kJ mol-1. In addition, NMR studies of the effect of the addition of benzene to chloroform solutions of the two carbohydrates showed that benzene specifically interacts with the hydrogen atoms of the pyranose ring at positions 3, 4, and 5 located on the α face of the methyl-β-galactoside, so it is, in fact, able to recognize it. Thus, the interactions between carbohydrates and the aromatic residues of proteins occur in the absence of the confinement generated by the protein structure. By experimentally measuring the energy associated with this interaction and comparing it to theoretical calculations, it was also possible to unequivocally determine the existence of CH/π interactions between carbohydrates and proteins.
Enthalpic nature of the CH/π interaction involved in the recognition of carbohydrates by aromatic compounds, confirmed by a novel interplay of NMR, calorimetry, and theoretical calculations
Ramirez-Gualito, Karla,Alonso-Rios, Rosa,Quiroz-Garcia, Beatriz,Rojas-Aguilar, Aaron,Diaz, Dolores,Jimenez-Barbero, Jesus,Cuevas, Gabriel
, p. 18129 - 18138 (2009)
Specific interactions between molecules, including those produced by a given solute, and the surrounding solvent are essential to drive molecular recognition processes. A simple molecule such as benzene is capable of recognizing and differentiating among very similar entities, such as methyl 2,3,4,6-tetra-O-methyl-α-D-galactopyranoside (α-Me5Gal), methyl 2,3,4,6-tetra-O-methyl-β-D-galactopyranoside (β-Me 5Gal), 1,2,3,4,6-penta-O-acetyl-β-D-galactopyranose (β-Ac5Gal), and methyl 2,3,4,6-tetra-O-methyl-α-D- mannopyranoside (α-Me5Man). In order to determine if these complexes are formed, the interaction energy between benzene and the different carbohydrates was determined, using Calvet microcalorimetry, as the enthalpy of solvation. These enthalpy values were -89.0 ± 2.0, -88.7 ± 5.5, -132.5 ± 6.2, and -78.8 ± 3.9 kJ mol-1 for the four complexes, respectively. Characterization of the different complexes was completed by establishing the molecular region where the interaction takes place using NMR. It was determined that β-Me5Gal is stabilized by the CH/π interaction produced by the nonpolar region of the carbohydrate on the α face. In contrast, α-Me5Man is not specifically solvated by benzene and does not present any stacking interaction. Although α-Me5Gal has a geometry similar to that of its epimer, the obtained NMR data seem to indicate that the axial methoxy group at the anomeric position increases the distance of the benzene molecules from the pyranose ring. Substitution of the methoxy groups by acetate moieties, as in β-Ac 5Gal, precludes the approach of benzene to produce the CH/π interaction. In fact, the elevated stabilization energy of β-Ac 5Gal is probably due to the interaction between benzene and the methyl groups of the acetyls. Therefore, methoxy and acetyl substituents have different effects on the protons of the pyranose ring.
Highly regioselective and stereoselective synthesis of C-Aryl glycosidesvianickel-catalyzedortho-C-H glycosylation of 8-aminoquinoline benzamides
Chen, Xi,Ding, Ya-Nan,Gou, Xue-Ya,Liang, Yong-Min,Luan, Yu-Yong,Niu, Zhi-Jie,Shi, Wei-Yu,Zhang, Zhe,Zheng, Nian
supporting information, p. 8945 - 8948 (2021/09/10)
C-Aryl glycosides are of high value as drug candidates. Here a novel and cost-effective nickel catalyzedortho-CAr-H glycosylation reaction with high regioselectivity and excellent α-selectivity is described. This method shows great functional group compatibility with various glycosides, showing its synthetic potential. Mechanistic studies indicate that C-H activation could be the rate-determining step.
TOLL-LIKE RECEPTOR 9 AGONISTS
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Page/Page column 35, (2009/02/10)
The present invention provides TLR9 agonists comprising, as an active ingredient, a compound represented by formula (I): (wherein a represents 0 or 1; n represents an integer of 0 to 2; m represents an integer of 0 to 5; X1 and X2 each independently represent a hydrogen atom or hydroxy; Y represents an oxygen atom or a sulfur atom; -Q1-represents -O- or the like; -Q2- represents -O- or the like; -Z- represents -O- or the like; R1, R3 and R4 each independently represent hydroxy or the like; R2 and R5 each independently represent a hydrogen atom, hydroxy or the like; and A represents 6-aminopurin-9-yl or the like) or a pharmaceutically acceptable salt thereof, and the like.
