Khatavi, S Y and Kantharaju, K and Yamanappa, H and Raghothama, S (2019) Rice husk SiO2 (NPs) supported-BO3H3: a highly active, solvent-free and recyclable catalyst to dihydropyrimidin-2(1H)ones-(thiones) and coumarin-3-carboxylic acid synthesis. In: CURRENT SCIENCE, 117 (11). pp. 1828-1841.
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Abstract
3,4-Dihydropyrimidin-2(1H)ones(thiones) (DHPM) and coumarin-3-carboxylic acid are obtained in excellent to good yield by employing green catalyst under solvent-free condition. The condensation of substituted arylaldehyde, 1,3-diketoester and urea/thiourea in the presence of green catalyst after 1 h of stirring at 50 degrees C resulted in DHPM. The reaction of substituted o-hydroxybenzaldehyde with Meldrum's acid in the presence of catalyst under sonication for a few minutes gave coumarin-3-carboxylic acid. Here, we have used Lewis acid catalyst RHA-SiO2(NPs)-BO3H3 derived from the agro-waste of rice husk, a heterogeneous catalyst for important organic scaffold synthesis. The reaction required low catalyst loading (1.2 mg) to achieve a target product under solvent-free condition. A series of other derivatives of heterogeneous catalysts synthesized are RHA-SiO2, RHA-SiO2(NPs), RHA-SiO2-BO3H3. We examined their catalytic activity in the synthesis of DHPM and coumarin-3-carboxylic acid. Only the reaction catalysed by RHA-SiO2(NPs)-BO3H3 gave excellent yield of the product. The final isolated pure product has been fully characterized by various spectroscopic methods and confirmed.
| Item Type: | Journal Article |
|---|---|
| Publication: | CURRENT SCIENCE |
| Publisher: | INDIAN ACAD SCIENCES |
| Additional Information: | Copyright of this article belongs to INDIAN ACAD SCIENCES |
| Keywords: | Agro-waste; coumarin-3-carboxylic acid; dihydropyrimidin-2(1H)ones(thiones); heterogeneous catalyst; rice husk |
| Department/Centre: | Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility) |
| Date Deposited: | 31 Dec 2019 06:02 |
| Last Modified: | 31 Dec 2019 06:02 |
| URI: | http://eprints.iisc.ac.in/id/eprint/64252 |
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