Mild One‐Step Synthesis of 4,6‐Benzylideneglycopyranosides from Aromatic Aldehydes and Gelation Abilities of the Glucose Derivatives

Abstract

We report herein an efficient one‐step synthesis of 4,6‐benzylidene glycoside derivatives from aromatic aldehydes bearing electron‐donating or ‐withdrawing groups as well as polymerisable monomer groups. Glucose, mannose and galactose derivatives could also be used successfully. Several of the glucose derivatives thus obtained acted as gelators for various solvents, including water. 4‐(n‐Butoxybenzylidene)glucose derivative 3a produced both a clear squalane gel and a hydrogel at 0.1 wt.‐%. Furthermore, 3‐(n‐butoxybenzylidene)glucose derivative 3i produced a clear organogel and an opaque hydrogel. The critical gelation concentration (CGC) of 3i in squalane was determined to be 0.02 wt.‐%, which is one of the lowest CGC values reported so far. The organogels, hydrogels and aqueous solution gels produced from 3a and 3d exhibited thixotropy. The strength and thixotropy of the organo‐ and hydrogel produced from 3a were estimated by a rheometer. The gel morphologies were observed by field‐emission and wet‐scanning electron microscopy, and the self‐assembly modes were analysed by XRD. We have concluded that super‐gelators can be created by this method.

Boron Effect on Sugar‐Based Organogelators

“…We described herein a series of alkylglucoside phenylboronic esters 1 (Figure 1) easily prepared in a single chemical step. Their chemical structures are similar to known benzylidene type organogelators 2 that already demonstrated their ability as good organogelators with typical minimum gelation concentration between 2 to 10 mg mL −1 [7e, j, 13] . The replacement of the acetal function by a boronic ester group induces two main differences; 1) the tetrahedral carbon is replaced by a planar boron atom and 2) the presence of a vacant orbital on the boron atom.…”

Synthesis of C2-Regioselectively Substituted Curdlan Acetate Propionate and the Effect of C2 Substituent on Their Properties

“…The Curdlan C4 and C6 hydroxyl groups were protected by acetalization in a homogeneous Curdlan/benzaldehyde/DMSO solution using pyridine as base, CSA as catalyst, and TMOF as dehydrating agent at 25 °C. − Unexpected gelation occurred when TMOF was added. This might be attributed to aggregation of the triple helix of 4,6-acetalized Curdlan that transformed from a random coil of the Curdlan chain through formation of an apolar exterior benzylidene structure at the acetalized C4 and C6 positions in DMSO. , After 3 days of acetalization, a softened transparent gel was obtained.…”

Carbohydrate Derived Organogelators and the Corresponding Functional Gels Developed in Recent Time

“…Shinkai and coworkers have synthesized several 4,6- O -arylidene derivatives of D-Glc, D-Gal, and D-Man under mild condition in one-step, using aromatic aldehydes in the presence of triethylorthoformate and cat. pTSA [62]. Several of these compounds form organogels with a variety of solvents, and two of these derivatives form hydrogels.…”