Maneesh Kumar Gupta

L-Proline catalysed multicomponent synthesis of 3-amino alkylated indolesvia a Mannich-type reaction under solvent-free conditions

An efficient L-proline catalyzed one-pot synthesis of 3-amino-alkylated indoles has been developed via a three-component Mannich-type reaction viz.secondary amines, aldehyde and indoles under solvent-free conditions at room temperature. Several amino acids (acidic, basic and neutral) have been screened for the reaction but the best results were obtained with L-proline.

Micelle promoted multicomponent synthesis of 3-amino alkylated indoles via a Mannich-type reaction in water

An efficient micelle promoted one-pot synthesis of 3-amino alkylated indoles has been developed via a three-component Mannich-type reaction from secondary amines, aldehydes and indoles in water under mild reaction conditions. In this Mannich-type reaction, micelles stabilize iminium ions, which undergo a nucleophilic addition of the indole to give 3-amino alkylated indoles in very good yields.

Nanoparticle catalyzed reaction (NPCR): ZnO-NP catalyzed Ugi-reaction in aqueous medium

The first ZnO-NP catalyzed Ugi type three-component (AB2C) reaction has been developed for the synthesis of 2-arylamino-2-phenylacetimidamide from an aldehyde, amine and isocyanide in aqueous media. This nanoparticle catalysed reaction (NPCR) is high yielding and has good atom economy as well as atom efficiency. The synthesized phenylacetimidamide yielded 2-amino-2-phenylacetamide on hydrolysis with I2–SDS–water, whereas alkaline hydrolysis afforded the N-substituted α-amino acid.

Micelle promoted supramolecular carbohydrate scaffold-catalyzed multicomponent synthesis of 1,2-dihydro-1-aryl-3H-naphth[1,2-e][1,3]oxazin-3-one and amidoalkyl naphthols derivatives in aqueous medium

Micelle promoted natural carbohydrate scaffold catalyzed synthesis of 1,2-dihydro-1-aryl-3H-naphth[1,2-e][1,3]oxazin-3-one and amidoalkyl naphthol derivatives have been developed via a multicomponent one pot reaction viz 2-naphthol/1-naphthol, aromatic/heteroaromatic aldehyde and urea/thiourea/amide in water. The advantages of this method are efficient catalysis, excellent cost effectiveness, simple work-up and recyclability of catalyst.

Catalyst-free hydroarylation of in situ generated ortho-quinone methide (o-QM) with electron rich arenes in water

We report the first C–H hydroarylation of in situ generated ortho-quinone methides with electron-rich arenes. The reaction takes place in water without any catalyst, and is highly regioselective. Ionic and non-ionic additives provide an increase in reaction rate, yield, and regioselectivity.

Amphiphile catalysed selective synthesis of 4-amino alkylated-1H-pyrazol-5-ol via Mannich aromatization preferred to the Knoevenagel–Michael type reaction in water

An economic and efficient amphiphile (SDS) catalysed one pot synthesis of the aromatized 4-amino alkylated-1H-pyrazol-5-ol via a Mannich type reaction that is preferable compared to a Knoevenagel–Michael type reaction, i.e. aromatic aldehyde, secondary amine and 3-methyl-1-phenyl-5-pyrazolinone in water, has been developed. In this selective Mannich aromatization, the reaction proceeds via a micelle stabilized imine intermediate, followed by the nucleophilic addition of 3-methyl-1-phenyl-5-pyrazolinone and aromatization in water.

Boric acid catalyzed Ugi three-component reaction in aqueous media

B(OH)3 catalyzed Ugi three-component reaction for the synthesis of 2-arylamino-2-phenylacetamide has been developed using aldehydes, amines, and isocyanides in water. The synthesized 2-arylamino-2-phenylacetamides were efficiently converted into α-amino acid via acidic hydrolysis.

A catalyst-free C–H hydroarylation of coumarin derived ortho-quinone methide (o-QM) with electron rich arenes in glycerol

An efficient, catalyst-free approach for C–H hydroarylation of in situ generated ortho-quinone methide (o-QM) with electron rich arenes (tertiary aryl amines) in glycerol has been developed. Several C-3-benzylated 4-hydroxycoumarin and 4-hydroxypyrone have been synthesized in good to excellent yields under mild conditions.

Cu(I)-catalyzed tandem decarboxylative/C–H activation coupling of cyclic diketones, proline and alkynes: synthesis of α-alkynylated pyrrolidine-oxyindoles

An efficient ligand/base and oxidant-free copper(I) catalyzed intermolecular direct alkynylation (IDA) strategy has been developed for the synthesis of α-alkynylated pyrrolidine-oxindole derivatives using cyclic diketones, amino acids and alkynes via tandem decarboxylative/C–H activation and reductive-amination strategy.