Kiran F. Shelke

Ionic liquid promoted synthesis of bis(indolyl) methanes

Abstract1-benzyl-3-methyl imidazolium hydrogen sulphate [bnmim][HSO4] was found to be an effective catalyst for the condensation reaction of indoles and derivatives with benzaldehydes in microwave irradiation with lower reaction time and higher yields to give bis(indolyl) methanes.

Cellulose sulfuric acid as a bio-supported and recyclable solid acid catalyst for the one-pot synthesis of 2,4,5-triarylimidazoles under microwave irradiation

Abstract A simple, rapid, and highly efficient method has been attempted for the three-component condensation of benzil/benzoin, aldehydes, and ammonium acetate under microwave irradiation in the presence of a catalytic amount of bio-supported cellulose sulfuric acid under solvent-free conditions to afford the 2,4,5-triarylimidazole derivatives. The catalyst is easily prepared, inexpensive, separated simply by filtration, gives excellent yield of products with shorter reaction times, and is recyclable several times.

Alum catalyzed simple and efficient synthesis of 5-arylidene-2,4-thiazolidinedione in aqueous media

Abstract Alum (KAl(SO4)2·12H2O) is an inexpensive, efficient, and non-toxic catalyst used for the synthesis of 5-arylidine-2,4-thiazolidinediones by the Knoevenagel condensation of aromatic aldehydes with 2,4-thiazolidinedione in aqueous media at 90°C. This method affords the 5-arylidine-2,4-thiazolidinediones in short reaction times, high yields, and green aspects by avoiding toxic catalysts and hazardous solvents.

An efficient ionic liquid promoted Knoevenagel condensation of 4-oxo-4H-benzopyran-3-carbaldehyde with Meldrum's acid

Abstract The green, mild, and efficient synthesis of 2, 2-dimethyl-5-[(4-oxo-4H-chromen-3-yl) methylene]-1, 3-dioxane-4, 6-diones by Knoevenagel condensation of 4-oxo-4H-benzopyran-3-carbaldehydes with Meldrums acid in presence of 1-benzyl-3-methylimidazolium chloride ((bnmim)(Cl)) ionic liquid at room temperature is reported. This method gives remarkable advantages such as a simple procedure, mild conditions, faster (10–20 min) reactions, and excellent yields. Additionally, the (bnmim)(Cl) was successfully recycled at least four times without significant loss of activity.

PEG-400 remarkably efficient and recyclable media for one-pot synthesis of various 2-amino-4H-chromenes

Abstract Polyethylene glycol-400 has been found to be a recyclable and rapid reaction medium for the synthesis of 2-amino-4H-chromenes by the condensation of aromatic aldehyde, malononitrile, and α-naphthol. This method gives remarkable advantages such as simple work up, high yields, and a greener method by avoiding toxic catalyst and hazardous solvents.

Dual role of ammonium acetate for solvent-free synthesis of 1,3-disubstituted-2,3-dihydro-1H-naphth-[1,2e] [1,3]-oxazine

Abstract Ammonium acetate plays a dual role for the solvent-free synthesis of 1,3-oxazine under neat heating at 60°C and under microwave irradiation with excellent yields. The synthetic strategy involved the formation of a Betti base which upon condensation with aromatic aldehydes gives the preferred oxazine ring. The present protocol contributes remarkable advantages, such as solvent- and catalyst-free reaction conditions, simple work-up procedures, shorter reaction times, and environmentally benign methodology.

Cellulose sulphuric acid as a biodegradable and reusable catalyst for the Knoevenagel condensation

A green, mild and efficient method for Knoevenagel condensation of 3-formylchromone/2-chlroquinoline-3-carbaldehyde with active methylene compounds such as Meldrum’s acid/ethyl cyanoacetate using biosupported cellulose sulphuric acid (CSA) in the solid-state by grinding under solvent-free condition has been developed. This method provides several advantages including environmental friendliness, shor t reaction times, high yields and a simple work-up procedure. Moreover, the CSA was successfully reused for four cycles without significant loss of activity.

An efficient one-pot synthesis of anthraquinone derivatives catalyzed by alum in aqueous media

Abstract Alum (KAl(SO4)2·12H2O) performs as a novel catalyst for the synthesis of anthraquinone derivatives from phthalic anhydride and substituted benzenes in good to excellent yields (70–96%) using water as a solvent at ambient temperature. Several solvents were examined for this reaction; however, in terms of reaction yield and time, water was found to be the optimum solvent. The remarkable advantages offered by this method are an inexpensive and easily available catalyst, a simple procedure, mild conditions, and much faster (60–120 min) reactions.