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Papers by Nongthombam Geetmani Singh

Research paper thumbnail of CCDC 1008429: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1443510: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1443423: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1024257: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1024256: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Facile Synthesis of 1,2-Disubstituted Benzimidazoles Usingp-Toluenesulfonic Acid through Grinding Method

Russian Journal of Organic Chemistry, 2020

An efficient synthetic method for the highly selective synthesis of pharmacologically active 1,2-... more An efficient synthetic method for the highly selective synthesis of pharmacologically active 1,2-disubstituted benzimidazole derivatives from o-phenylenediamine and various aromatic aldehydes catalyzed by p-toluenesulfonic acid through grinding under solvent-free condition is described. The reaction requires the catalyst only during the conversion of intermediate N,N′-dibenzylidene-o-phenylenediamine into the desired product. The products were obtained within a short time with good yields by using only a mortar and pestle, which makes the proposed method convenient and cost-effective.

Research paper thumbnail of N,N′-Dialkyl-4-Aryl-3,4-Dihydropyrimidinones and Thiones: Ceric Ammonium Nitrate Catalyzed Synthesis and Molecular Structure Determination by X-ray Crystallography

Journal of Heterocyclic Chemistry, 2016

This work presents a microwave assisted solvent-free synthesis of N,N′-dialkyl-4-aryl-3,4dihydrop... more This work presents a microwave assisted solvent-free synthesis of N,N′-dialkyl-4-aryl-3,4dihydropyrimidinones/thiones in the presence of Ceric Ammonium Nitrate (CAN) via direct condensation of aromatic aldehydes, β-keto ester, and N,N′-dialkylurea/thiourea. The highlights of the methodology adopted are (i) facile condensation of the reactants into product without any side-products, and (ii) short reaction time with high yield and good purity. All the compounds synthesized were characterized and established by spectroscopic techniques such as FTIR, 1 H NMR, 13 C NMR, and Mass. The structure of the compound is further corroborated by single crystal X-ray diffraction analysis.

Research paper thumbnail of Synthetic, mechanistic and kinetic studies on the organo-nanocatalyzed synthesis of oxygen and nitrogen containing spiro compounds under ultrasonic conditions

Green Chemistry, 2016

Vitamin B1 functionalised nano-ferrites: an organo-nanocatalyst for the synthesis of various spir... more Vitamin B1 functionalised nano-ferrites: an organo-nanocatalyst for the synthesis of various spiro derivatives.

Research paper thumbnail of A convenient and greener synthesis of bis(indolyl)methanes in surfactant medium under microwave irradiation

Research paper thumbnail of Cupric acetate catalysed alkylation of indoles inwater:Acomparative study between conventional heating andmicrowave irradiation

Research paper thumbnail of Bakers' yeast: an environment benign catalyst for the one-pot synthesis of indolyl chromenes and bisindolyl alkanes

Green Chemistry Letters and Reviews, 2014

Research paper thumbnail of CCDC 1008429: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1443510: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1443423: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1024257: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of CCDC 1024256: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Research paper thumbnail of Facile Synthesis of 1,2-Disubstituted Benzimidazoles Usingp-Toluenesulfonic Acid through Grinding Method

Russian Journal of Organic Chemistry, 2020

An efficient synthetic method for the highly selective synthesis of pharmacologically active 1,2-... more An efficient synthetic method for the highly selective synthesis of pharmacologically active 1,2-disubstituted benzimidazole derivatives from o-phenylenediamine and various aromatic aldehydes catalyzed by p-toluenesulfonic acid through grinding under solvent-free condition is described. The reaction requires the catalyst only during the conversion of intermediate N,N′-dibenzylidene-o-phenylenediamine into the desired product. The products were obtained within a short time with good yields by using only a mortar and pestle, which makes the proposed method convenient and cost-effective.

Research paper thumbnail of N,N′-Dialkyl-4-Aryl-3,4-Dihydropyrimidinones and Thiones: Ceric Ammonium Nitrate Catalyzed Synthesis and Molecular Structure Determination by X-ray Crystallography

Journal of Heterocyclic Chemistry, 2016

This work presents a microwave assisted solvent-free synthesis of N,N′-dialkyl-4-aryl-3,4dihydrop... more This work presents a microwave assisted solvent-free synthesis of N,N′-dialkyl-4-aryl-3,4dihydropyrimidinones/thiones in the presence of Ceric Ammonium Nitrate (CAN) via direct condensation of aromatic aldehydes, β-keto ester, and N,N′-dialkylurea/thiourea. The highlights of the methodology adopted are (i) facile condensation of the reactants into product without any side-products, and (ii) short reaction time with high yield and good purity. All the compounds synthesized were characterized and established by spectroscopic techniques such as FTIR, 1 H NMR, 13 C NMR, and Mass. The structure of the compound is further corroborated by single crystal X-ray diffraction analysis.

Research paper thumbnail of Synthetic, mechanistic and kinetic studies on the organo-nanocatalyzed synthesis of oxygen and nitrogen containing spiro compounds under ultrasonic conditions

Green Chemistry, 2016

Vitamin B1 functionalised nano-ferrites: an organo-nanocatalyst for the synthesis of various spir... more Vitamin B1 functionalised nano-ferrites: an organo-nanocatalyst for the synthesis of various spiro derivatives.

Research paper thumbnail of A convenient and greener synthesis of bis(indolyl)methanes in surfactant medium under microwave irradiation

Research paper thumbnail of Cupric acetate catalysed alkylation of indoles inwater:Acomparative study between conventional heating andmicrowave irradiation

Research paper thumbnail of Bakers' yeast: an environment benign catalyst for the one-pot synthesis of indolyl chromenes and bisindolyl alkanes

Green Chemistry Letters and Reviews, 2014