Covalently immobilized indium(III) composite (In/SiO2) as highly efficient reusable catalyst for A3-coupling of aldehydes, alkynes and amines under solvent-free conditions

• Published in: Journal of molecular catalysis. A, Chemical Vol. 399; pp. 71 - 78
• Main Authors: Silva, Tiago Lima da, Rambo, Raoní Scheibler, Rampon, Daniel da Silveira, Radatz, Cátia Schwartz, Benvenutti, Edilson Valmir, Russowsky, Dennis, Schneider, Paulo Henrique
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-04-2015
• Subjects: Indium; Multicomponent reaction; Propargylamines; Silica xerogel; Supported catalyst; Silica xerogel; Multicomponent reaction; Indium; Propargylamines; Supported catalyst
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2015.01.021

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Indium-Silicon linked: A recyclable well characterized hybrid catalyst has been applied in A3-coupling solvent free reaction under conventional and microwave heating to afford propargylamines in high yields.
•Synthesis and complete characterization of a supported indium composite (In/SiO2).•Identification that the indium is bonded to silica through covalent InOSi bonds.•Synthesis of propargylamines through an A3-coupling reaction promoted by In/SiO2.•Microwave assisted reactions.•The supported In composite could be reused for four times without losing efficiency.
We describe the synthesis and application of a silica-xerogel-supported indium(III) composite (In/SiO2). Using X-ray photoelectron spectroscopy, by the first time it was possible to identify that the indium is bonded to the silica through covalent InOSi bonds. The N2 adsorption/desorption isotherms revealed that the In/SiO2 composite presents pores with diameters between 1 and 4nm, which allows it to be used as a heterogeneous catalyst. Thus, this composite was used as catalyst in an A3-coupling reaction with several aldehydes, amines and acetylenes, leading to the formation of propargylamines in good-to-excellent yields in solvent-free conditions, using both conventional heating and microwave irradiation (MW). The recyclability was evaluated under both conditions and no considerable reduction in the yields was observed after four cycles.