Synthesis of a Series of Trimeric Branched Glycoconjugates and Their Applications for Supramolecular Gels and Catalysis

Abstract

Carbohydrate-derived molecular gelators have found many practical applications as soft materials. To better understand the structure and molecular gelation relationship and further explore the applications of sugar-based gelators, we designed and synthesized eight trimeric branched sugar triazole derivatives and studied their self-assembling properties. These included glucose, glucosamine, galactose, and maltose derivatives. Interestingly, the gelation properties of these compounds exhibited correlations with the peripheral sugar structures. The maltose derivative did not form gels in the tested solvents, but all other compounds exhibited gelation properties in at least one of the solvents. Glucose derivatives showed superior performance, followed by glucosamine derivatives. They typically formed gels in toluene and alcohols; some formed gels in ethanol-water mixtures or DMSO water mixtures. The glycoclusters 9 and 10 demonstrated rate acceleration for the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. These were further studied for their metallogels formation properties, and the copper metallogels from compound 9 were successfully utilized to catalyze click reactions. These metallogels were able to form a gel column, which was effective in converting the reactants into the triazole products in multiple cycles. Moreover, the same gel column was used to transform a second click reaction using different reactants. The synthesis and characterization of these compounds and their applications for catalytic reactions were discussed.

Synthetic approaches of carbohydrate based self-assembling systems

“…Wang's group designed, synthesized, and characterized a series of glycoconjugates via a click reaction of various trimeric, tetrameric, and hexameric alkynes with glycosyl azides (Scheme 26). 88–90 Using pentaerythritol alkyne as the core structure, click reactions with azido sugars afforded a library of glycoclusters with different degrees of conjugation. The monomeric and dimeric glycosyl triazole derivatives tend to be soluble in most of the organic solvents tested, but compounds with three and four branches of sugar triazole units were found to be effective gelators for water and organic solvents.…”

“…In a related study, eight trimeric glycoclusters from different sugar azides were prepared and analyzed. 90 The resulting glycoclusters formed different SA structures depending on the sugar structures. Galactose and maltose derivatives did not form hydrogels.…”

Substrate-Controlled Diversity-Oriented Synthesis of Novel Polycyclic Frameworks via [4 + 2] and [3 + 2] Annulations of Ninhydrin-Derived MBH Adducts with 3,4-Dihydroisoquinolines

“…Polycyclic rings are the important frameworks as a core structure widespread throughout most classes of natural and non-natural products with a wide spectrum of pharmacological and biological activities, which makes them arouse ever-increasing attention in organic and medicinal chemistry [1][2][3][4][5][6][7]. The polycyclic compounds containing some privileged structures, such as tetrahydroisoquinoline motifs [8][9][10], tetrahydropyrrole moieties [11][12][13] or indane-1,3-dione units [14,15] and so on, especially play a key role in drug discovery and development.…”

“…Purification by flash chromatography (PE/EA = 3:1 as an eluent, R f = 0.32) gave a yellow solid (32.1 mg, 86% yield), mp 117-118 • C,1 H NMR (400 MHz, CDCl 3 ) δ 8.10 (d, J = 7.6 Hz, 1H), 7.82 (t, J = 7.2 Hz, 1H), 7.72 (t, J = 7.6 Hz, 1H), 7.57 (d, J = 7.6 Hz, 1H), 7.46 (s, 1H), 7.09 (d, J = 7.6 Hz, 1H), 7.03 (t, J = 7.6 Hz, 1H), 6.71 (t, J = 7.6 Hz, 1H), 6.20 (d, J = 8.0 Hz, 1H), 3.70 (dd, J = 13.2, 5.2 Hz, 1H), 3.46-3.39 (m, 4H), 3.23-3.14 (m, 1H), 2.74 (d, J = 15.2 Hz, 1H), 1.74 (s, 3H) ppm 13. C NMR (100 MHz, CDCl 3 ) δ 199.6, 199.5, 164.9, 150 5,. 143.1, 142.2, 136.8, 135.5, 135.3, 134.5, 129.6, 127.2, 126.0, 125.7, 123.1, 123.0, 100.5, 72.0, 69.1, 50.6, 42.5, 30.7, 25.4 ppm.…”