Hydrotalcite: recyclable, novel heterogeneous catalyst for facile, environmentally benign and high yielding multi-component synthesis and mechanistic study under solvent free conditions
2012; Royal Society of Chemistry; Volume: 2; Issue: 12 Linguagem: Inglês
10.1039/c2cy20067h
ISSN2044-4761
AutoresPramod K. Sahu, Praveen Kumar Sahu, Raginee Jain, Ramjilal Yadav, Dau D. Agarwal,
Tópico(s)Microwave-Assisted Synthesis and Applications
ResumoThe synthesis of the 4H-pyrimido[2,1-b][1,3]benzothiazole (1a–1h), 1,2,4-triazoloquinazolines (2a,2b), octahydroquinazolinones (3a,3b) and fused thiazolo[2,3-b]quinazolinone (4a,4b) by multicomponent reactions using aldehydes, dicarbonyl and 2-amino benzothiazole/3-amino-1,2,4-triazole/urea/thiorea has been carried out in the presence of Mg–Al–CO3 and Ca–Al–CO3 hydrotalcite as a heterogeneous catalyst. Hydrotalcites need short reaction times, are non-toxic, easy to work up and reusable under solvent free conditions, hence making this process environment friendly. A detailed mechanistic study shows that the reaction using urea proceeds through imine intermediate 6. In addition, we have isolated and characterized the key intermediate of the reaction by using hydrotalcite.
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