Heterogeneous graphene oxide as recyclable catalyst for azomethine ylide mediated 1,3 dipolar cycloaddition reaction in aqueous medium

Abstract

Graphene oxide (GO) catalyzed regio and diastereoselective synthesis of spiro-indenoquinoxaline pyrrolizidines and spiro-oxindoles pyrrolizidines is described with good substrate scope and yield using azomethine ylide under aq. EtOH condition at RT.

Highly efficient catalyst-free domino conjugate addition, decarboxylation and esterification/amidation of coumarin carboxylic acid/esters with pyrazolones: a green chemistry approach

“…In recent times, various investigations have focused on nontraditional synthetic protocols to replace volatile harmful solvents with green solvents, such as aqueous media, ionic liquids, and medium derived from natural feedstocks or solvent-free conditions. 32, 43 In pursuit of developing a green methodology for the synthesis of bioactive molecules, 33 we began our study for the synthesis of pyrazolyl phenyl propionates 3 with coumarin 3-carboxylic acid 1a and 5-methyl-2,4dihydro-3H-pyrazol-3-one 2a (Scheme 2). The reaction was performed in various solvents for solvent screening at room temperature for 48 h but did not yield any product.…”

Catalyst‐Free One‐Pot Regioselective Synthesis of Spiropyrrolizines Using 1,3‐Dipolar Cycloaddition Reaction

“…Synthesis of spiro[acenaphthylene-1,3'-pyrrolizin]-2-ones. [a] Reactions carried out using acenaphthenequinone (1.0 mmol), Lproline/L-thioproline (1.0 mmol) and 3-methyl-4-nitro-5-styrylisoxazole (1.0 mmol) in refluxing MeOH (3 mL) During the progression of our work, we came across a report by Reddy et al 16 on the synthesis of spiro[indeno [1,2-b] quinoxaline-11,3'-pyrrolizines using graphene oxide as catalyst unlike catalyst free synthesis having general applicability and higher yields observed by us.…”

Recent advances in the catalytic applications of GO/rGO for green organic synthesis

“…The presence of carboxyl groups boosts ipso-hydroxylation as revealed by the control experiments, and GO can be reused several times without losing its activity. Furthermore, GO has been successfully utilized as a green carbocatalyst for the synthesis of numerous biologically relevant scaffolds such as benzylbarbiturocoumarin derivatives [169], 3-dihydroquinazolinones and quinazolin-4-(3H)-ones [170] and benzylpyrazolyl coumarin derivatives [171], 2,5-dimethyl-N-phenyl pyrrole [172], poly heterocyclic spiro-indeno quinoxaline pyrrolizidines quinoxalin and spiro-oxindoles pyrrolizidines [173], 3-sulfenylimidazo[1,2-a]pyridines [174], dihydro-2-oxopyrroles [175], etc. Roy et al [176] developed an eco-friendly method for the synthesis of library of bioactive nitrogen containing heterocycles, quinoxalines [177] from 2-nitroanilines under entirely metal-free conditions using GO or rGO as a green catalyst (Scheme 12).…”