Application of ionic liquids in enzymic resolution by hydrolysis of cycloalkyl acetates

Synthesis and characterization of nitrogen-based ionic liquids bearing allyl groups and examples of their application

The synthesis and characterization of a series of allyl-functionalized ionic liquids and examples of their application in catalysts and surface-functionalizing compound formation.

Improved enzyme-mediated synthesis and supramolecular self-assembly of naturally occurring conjugates of β-sitosterol

Naturally occurring acylated β-sitosteryl glucosides have been investigated for their novel properties. The synthetic protocol based on the literature data was improved and optimized. The main improvement consists in employing systems of ionic liquids combined with organic solvents in lipase-mediated esterification of (3β)-stigmast-5-en-3-yl β-d-glucopyranoside to get (3β)-stigmast-5-en-3-yl 6-O-acyl-β-d-glucopyranosides. Maximum yields of these products were achieved with Candida antarctica lipase B immobilized on Immobead 150, recombinant from yeast, in absolute THF and in the presence of either ionic liquid [1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM]BF₄) or 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM]PF₆)] employed. Pharmacological activity of (3β)-stigmast-5-en-3-yl 6-O-acyl-β-d-glucopyranosides was studied in tests on MCF7 tumor cell lines; the compounds displayed moderate activity which was higher than the activity of β-sitosterol. Supramolecular characteristics were discovered at (3β)-stigmast-5-en-3-yl 6-O-dodecanoyl-β-d-glucopyranoside that formed supramolecular polymer through multiple H-bonds in a methanol/water system (60/40). Its formation was confirmed by the independent UV-vis measurements during certain time period, by variable temperature DOSY-NMR measurement in deuteriochloroform, and visualized by transmission electron microscopy (TEM) and atomic force microscopy (AFM) showing chiral helical structures and complex superassembly systems based on fibrous supramolecular polymer. In contrary, no such properties have been observed for the other two (3β)-stigmast-5-en-3-yl 6-O-acyl-β-d-glucopyranosides under the given experimental conditions.

Use of pyridinium ionic liquids as catalysts for the synthesis of 3,5-bis(dodecyloxycarbonyl)-1,4-dihydropyridine derivative

The synthesis of cationic amphiphilic 1,4-dihydropyridine derivative, potential gene delivery agent is achieved via an efficient multi-step sequence. The key step of this approach is a two-component Hantzsch type cyclisation of 3-oxo-2-[1-phenylmethylidene]-butyric acid dodecyl ester and 3-amino-but-2-enoic acid dodecyl ester utilising bis(2-hydroxyethyl)ether as a solvent and 1-butyl-4-methylpyridinium chloride as a catalyst. The 1,4-dihydropyridine derivative with long alkyl ester chains at positions 3 and 5 of the 1,4-DHP ring — 3,5-bis(dodecyloxycarbonyl)-2,6-dimethyl-4-phenyl-1,4-dihydropyridine was obtained in substantially higher yield with respect to classical Hantzsch synthesis. Bromination of this compound followed by nucleophilic substitution of bromine with pyridine gave the desired cationic amphiphilic 1,4-dihydropyridine.