Highly efficient mesoporous base catalyzed Knoevenagel condensation of different aromatic aldehydes with malononitrile and subsequent noncatalytic Diels–Alder reactions
✍ Scribed by John Mondal; Arindam Modak; Asim Bhaumik
- Book ID
- 104059333
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 822 KB
- Volume
- 335
- Category
- Article
- ISSN
- 1381-1169
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✦ Synopsis
Knoevenagel condensation and [4 + 2] cycloaddition reactions are very important class of reactions in synthetic organic chemistry. We have prepared amino-functionalized mesoporous silica through cocondensation of 3-aminopropyltriethoxy-silane (APTES) along with tetraethylorthosilicate (TEOS) in presence of a cationic surfactant CTAB hydrothermally. Small angle powder XRD, HR TEM, FE SEM, N 2 sorption and FT IR spectroscopic tools are used to characterize the 2D-hexagonal mesostructure and to identify the presence of surface -NH 2 groups in amino-functionalized mesoporous silica material. Our experimental results reveal that amino-functionalized mesoporous silica is an efficient base catalyst for the Knoevenagel condensation of different aromatic aldehydes with malononitrile to ␣,-unsaturated dicyanides under very mild reaction condition and in the presence of ethanol solvent. The isolated ␣,unsaturated dicyanides obtained through the condensation reaction further react very efficiently with cyclopentadiene to form a series of Diels-Alder cycloaddition products in excellent yields in the absence of any catalyst.