Starch mediates and cements densely magnetite-coating of talc, giving an efficient nano-catalyst for three-component synthesis of imidazo[1,2-c]quinazolines.

Hot-water-soluble starch (HWSS) was used as a powerful cementing material to produce nano-size conglomerates of talc and magnetite nanoparticles. Coordination of HWSS hydroxyl groups to iron atoms at surface of magnetite leads to grafting and encapsulation of its nanoparticles. The resulting nano-complex showed a higher loading capacity on talc than pristine magnetite nanoparticles.

Expedient synthesis of novel antibacterial hydrazono-4-thiazolidinones under catalysis of a natural-based binary ionic liquid.

A library of pyran-2H-one-3-ylmethylidene and chromene-2H-one-3-ylmethylidene derivatives of the titled heterocyclic framework was synthesized from 3-acyl-4-hydroxypyran/chromene-2H-one via sequential reaction with thiosemicarbazide and dialkyl acetylenedicarboxylates. The syntheses were carried out under efficient catalysis of a new binary ionic liquid mixture [L-prolinium chloride][1-methylimidazolium-3-sulfonate] in one pot and solvent-free conditions. Calculations based on density functional theory displayed that the barrier energy for interconversion of the two possible diastereomeric isomers of each product is less than the thermal energy of molecules at room temperature, as only one product can be resolved from a given reaction mixture.

Synthesis of symmetrical and unsymmetrical 3,3-di(indolyl)indolin-2-ones under controlled catalysis of ionic liquids.

Three ionic liquids, [BMIM][BF] doped with 60 mol % of LiCl ([BMIM][BF]-LiCl), ,,,-tetramethylguanidinium trifluoroacetate (TMGT), and ,,,-tetramethylguanidinium triflate (TMGT) were found useful as catalyst solvents for controlled 3-indolylation of isatins. Our investigation revealed that the reaction between isatin and indoles in [BMIM][BF]-LiCl or TMGT media stops at the step of addition of the two components providing 3-indolyl-3-hydroxyindolin-2-ones while the ionic liquid TMGT runs the reaction further through accompanying Friedel-Crafts substitution to afford symmetrical 3,3-di(indol-3-yl)indolin-2-ones. To take advantage of the difference between the effects of these ionic liquids on the reaction progress, we planned a two-step protocol for the efficient synthesis of unsymmetrical 3,3-di(indol-3-yl)indolin-2-ones.

Silica-bound benzoyl chloride mediated the solid-phase synthesis of 4H-3,1-benzoxazin-4-ones.

The solid-phase synthesis of 4H-3,1-benzoxazin-4-ones was achieved using silica-bound benzoyl chloride (SBBC) as dehydrating agent in reaction with 2-acylaminobenzoic acids. The silica-grafted reagent (SBBC) was simply recovered after reaction and reused several times.