Rajive Gupta

Catalytic properties of several palladium complexes covalently anchored onto silica for the aerobic oxidation of alcohols

A series of novel silica-supported palladium catalysts bearing N–N, N–S and N–O chelating ligands have been prepared and tested for the aerobic oxidation of alcohols to carbonyl compounds. The most active catalyst, 1, was used for the oxidation of a series of primary and secondary alcohols to carbonyl compounds. The catalyst is highly selective and no over-oxidation products were detected. The catalyst 1 can also be used for the oxidation of primary benzyl alcohols to carbonyl compounds with comparable yields in the presence of atmospheric air.

Microwave assisted solvent-free synthesis of pyrazolo[3,4-b]quinolines and pyrazolo[3,4-c]pyrazoles using p-TsOH

Pyrazolo[3,4-b]quinolines and pyrazolo[3,4-c]pyrazoles have been synthesized from β-chlorovinylaldehydes and hydrazine hydrate/phenylhydrazine using p-TsOH under microwave irradiation.

Ac2O-Py/basic alumina as a versatile reagent for acetylations in solvent-free conditions under microwave irradiation

Abstract Acetic anhydride–pyridine over basic alumina has been used in order to carry out acetylations of hydroxy, thiol and amino groups in solvent-free conditions under microwave irradiation. The technique can be extended for selective acetylations by regulation of irradiation time.

MICROWAVE-INDUCED SOLVENT-FREE SYNTHESIS OF 2-ARYLBENZOTHIAZOLES USING p-TsOH

ABSTRACT A simple and efficient procedure has been developed for the synthesis of 2-arylbenzothiazoles by a one-pot reaction of o-aminothiophenol with β-chlorocinnamaldehydes using p-TsOH under microwave irradiation.

Microwave-induced selective synthesis of α-bromo and α,α-dibromoalkanones using dioxane–dibromide and silica gel under solvent-free conditions

Abstract Selective synthesis of α-bromo and α,α-dibromoalkanones using dioxane–dibromide and silica gel in solvent-free conditions under microwave irradiation has been reported. The amount of dioxane–dibromide, silica gel and time of irradiation are keys for the selective synthesis of α-bromo and α,α-dibromoalkanones.

Efficient and novel one-pot synthesis of antifungal active 1-substituted-8-aryl-3-alkyl/aryl-4H-pyrazolo[4,5-f][1,2,4]triazolo[4,3-b][1,2,4]triazepines using solid support

A simple, efficient and environment-friendly procedure is developed for the synthesis of 1-substituted-8-aryl-3-alkyl/aryl-4H-pyrazolo[4,5-f][1,2,4]triazolo[4,3-b][1,2,4]triazepines in the presence of N,N-dimethylformamide as an energy transfer medium, p-TsOH as catalyst and basic alumina as solid support under microwave irradiation. The products are obtained in moderate to good yields and are in a state of high purity. Moreover, title compounds have been screened for antifungal activity.

An Efficient Procedure for the Synthesis of Spiro (3H-Indole-3,4′ (1′H)pyrano[2,3-C]pyrrole]-5′-carbonitriles Using Solid Inorganic Supports and Microwave Activation

Abstract Microwave irradiation accelerates the Michael condensation of 3-dicyanomethylene-2H-indole-2-one with 2-pyrrolidone/ N-methy1-2-pyrrolidone (i) adsorbed on neutral alumina in “dry media” (ii) using absolute ethanol as energy transfer medium. 3-Dicyanoniethylene-2H-indol-2-one was synthesized under microwave irradiation using indole-2,3-dione and malononitrile. The results were compared with those obtained following the classical method. The advantages obtained by the use of microwave irradiation are demonstrated.

Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in water

Summary The Knoevenagel condensation between aromatic aldehydes and malononitrile, ethyl cyanoacetate or malonic acid with hydroxyapatite supported caesium carbonate in water is described. HAP–Cs2CO3 was found to be a highly active, stable and recyclable catalyst under the reaction conditions.

PhCOCl-Py/Basic Alumina as a Versatile Reagent for Benzoylation in Solvent-Free Conditions

A solvent-free procedure using PhCOCl-Py/basic alumina under microwave irradiation has been developed for N-, O- and S-benzoylation.

A Simple and Selective Procedure for α-Bromination of Alkanones Using Hexamethylenetetramine-bromine Complex and Basic Alumina in Solvent-Free Conditions

Abstract α-Bromoalkanones 2 were synthesized by the reaction of alkanones 1 with hexamethylenetetramine-bromine complex and basic alumina in solvent-free conditions under microwave irradiation.