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Yamanappa, H.
- 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
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Authors
Affiliations
1 Department of Chemistry, Peptide and Medicinal Chemistry Research Laboratory, Rani Channamma University, Vidyasangama, P-B, NH-4, Belagavi 591 156, IN
2 NMR Research Centre, Indian Institute of Science, Bengaluru 560 012, IN
1 Department of Chemistry, Peptide and Medicinal Chemistry Research Laboratory, Rani Channamma University, Vidyasangama, P-B, NH-4, Belagavi 591 156, IN
2 NMR Research Centre, Indian Institute of Science, Bengaluru 560 012, IN
Source
Current Science, Vol 117, No 11 (2019), Pagination: 1828-1841Abstract
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 sol-vent-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°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 heteroge-neous catalyst for important organic scaffold synthe-sis. The reaction required low catalyst loading (1.2 mg) to achieve a target product under solvent-free condition. A series of other derivatives of heterogene-ous catalysts synthesized are RHA–SiO2, RHA–SiO2(NPs), RHA–SiO2–BO3H3. We examined their catalytic activity in the synthesis of DHPM and cou-marin-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.Keywords
Agro-Waste, Coumarin-3-Carboxylic Acid, Dihydropyrimidin-2(1H)ones(Thiones), Heterogeneous Catalyst, Rice Husk.Full Text
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