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DOI: 10.1055/s-0031-1289491
One-Pot Tandem Reactions with a Bifunctional Solid Catalyst
Mesoporous Silica with Site-Isolated Amine and Phosphotungstic Acid Groups: A Solid Catalyst with Tunable Antagonistic Functions for One-Pot Tandem Reactions.
Angew. Chem. Int. Ed. 2011;
50: 9615-9619
Publikationsverlauf
Publikationsdatum:
19. Dezember 2011 (online)
Key words
bifunctional acid–base catalysis - one-pot synthesis - mesoporous silica - phosphotungstic acid![](https://www.thieme-connect.de/media/synfacts/201201/y145_s1.gif)
Significance
A mesoporous silica catalyst 3 bearing both Brønsted base and acid groups was prepared by immobilization of 3-aminopropyltriethoxysilane [(EtO)3Si(CH2)3NH2] and phosphotungstic acid (H3PW12O40) to a mesoporous silica. Catalyst 3 drove the tandem deacetalization–Henry reaction and deacetalization–Knoevenagel reaction of 4 with nitromethane and malononitrile to give trans-1-nitro-2-phenylethylene 5 and benzylidene malononitrile 6 in 92% and 91% yield, respectively.
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Comment
The acid/base properties were controlled by the ratio and surface concentration of an amino group and phosphotungstate. Catalyst 3 was characterized by XANES (X-ray absorption near-edge structure spectrum), BET, BJH, 31P NMR, 29Si and 13C CP-MAS NMR spectroscopy and GC-MS. Catalyst 3 was recovered by filtration and reused several times without significant loss of catalytic activity (4th use: 5 in 90% isolated yield, 6 in 91% isolated yield).
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![](https://www.thieme-connect.de/media/synfacts/201201/y145_s1.gif)