Novel ionic liquids—Imidazolium salts with a difluoromethylene fragment directly bonded to the nitrogen atom

Alkylation of N-(1,1,2,2-tetrafluoroethyl)imidazole (1) by alkyl iodides and metathesis resulting in corresponding tetrafluoroborates and bis(trifluoromethanesulfonyl)amides led to the formation of new type stable ambient temperature ionic liquids 3 and 4 with a difluoromethylene fragment directly bonded to the nitrogen atom.     

Synthesis and Characterization of a Helicene‐Based Imidazolium Salt and Its Application in Organic Molecular Electronics

Herein we demonstrate the synthesis of a helicene‐based imidazolium salt. The salt was prepared by starting from racemic 2‐methyl[6]helicene, which undergoes radical bromination to yield 2‐(bromomethyl)[6]helicene. Subsequent treatment with 1‐butylimidazole leads to the corresponding salt 1‐butyl‐3‐(2‐methyl[6]helicenyl)‐imidazolium bromide. The prepared salt was subsequently characterized by using NMR spectroscopy and X‐ray analysis, various optical spectrometric techniques, and computational chemistry tools. Finally, the imidazolium salt was immobilized onto a SiO₂ substrate as a crystalline or amorphous deposit. The deposited layers were used for the development of organic molecular semiconductor devices and the construction of a fully reversible humidity sensor.     

Aminopolyols from Carbohydrates: Amination of Sugars and Sugar‐Derived Tetrahydrofurans with Transaminases

Carbohydrates are the major component of biomass and have unique potential as a sustainable source of building blocks for chemicals, materials, and biofuels because of their low cost, ready availability, and stereochemical diversity. With a view to upgrading carbohydrates to access valuable nitrogen‐containing sugar‐like compounds such as aminopolyols, biocatalytic aminations using transaminase enzymes (TAms) have been investigated as a sustainable alternative to traditional synthetic strategies. Demonstrated here is the reaction of TAms with sugar‐derived tetrahydrofuran (THF) aldehydes, obtained from the regioselective dehydration of biomass‐derived sugars, to provide access to cyclic aminodiols in high yields. In a preliminary study we have also established the direct transamination of sugars to give acyclic aminopolyols. Notably, the reaction of the ketose d ‐fructose proceeds with complete stereoselectivity to yield valuable aminosugars in high purity.     

A Novel Ionic Liquid Based on Imidazolium Cation as an Efficient and Reusable Catalyst for the One‐pot Synthesis of Benzoxazoles,Benzthiazoles, Benzimidazoles and 2‐Arylsubstituted Benzimidazoles

A novel dicationic ionic liquid based on imidazolium cation is designed, synthesized and successfully used as catalyst for the one‐pot synthesis of benzoxazoles, benzthiazoles, benzimidazoles and 2‐arylsubstituted benzimidazoles. The remarkable feature of this new catalyst is its ethyleneoxy bridge which participates in dissolving organic compound in ionic liquid. The application of this ionic liquid is studied in a new one‐pot method for synthesis of heterocyclic compounds under solvent‐free conditions. Simple and convenient procedure, high conversion, reusability of catalyst, easy purification and shorter reaction time are the advantageous features of this method.     

Direct Addition of Amides to Glycals Enabled by Solvation‐Insusceptible 2‐Haloazolium Salt Catalysis

The direct 2‐deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2‐deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2‐deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2‐deoxyglycosylation of amide groups using a newly designed Brønsted acid catalyst under mild conditions. Through mechanistic investigations, we discovered that the amide group can inhibit acid catalysts, and the inhibition has made the 2‐deoxyglycosylation reaction difficult. Diffusion‐ordered two‐dimensional NMR spectroscopy analysis implied that the 2‐chloroazolium salt catalyst was less likely to form aggregates with amides in comparison to other acid catalysts. The chlorine atom and the extended π‐scaffold of the catalyst played a crucial role for this phenomenon. This relative insusceptibility to inhibition by amides is more responsible for the catalytic activity than the strength of the acidity.