SA-Supported Organic Amines as Heterogeneous Catalysts

Significance

The silica-alumina (SA) supported amines 1 and 2 were developed as heterogeneous organic base catalysts for a variety of carbon-carbon bond-forming reactions. The reaction of amorphous SA with 3-(diethylamino)propyltriethoxysilane in toluene gave the SA-supported amine 1 (SA-NEt₂). SA-supported amine 2 (SA-NH₂) was also prepared by a similar procedure. SA-NEt₂ (1) showed high catalytic activity in the Michael reaction of ethyl cyanoacetate to methyl vinyl ketone (eq. 1) and cyanoethoxycarbonylation of benzaldehyde (eq. 2), respectively. SA-NH₂ (2) catalyzed the nitro-aldol reaction of nitromethane with benzaldehyde to give β-nitrostyrene quantitatively (eq. 3).