Dendronized piperidine: highly effective and recyclable catalysts for Henry reaction

Abstract Two types of dendronized tertiary amines were synthesized by attaching piperidine to the core of a Frechet-type dendrimer or to the end of an alkyl chain that is linked to the dendritic core. The relationship between structure and property of the catalysts in the Henry reaction of 2-nitrobenzaldehyde and nitromethane was established. It was observed that the attachment of piperidine to the dendritic sector by using a hexamethylene chain effectively avoids the scenario of dendritic shell encapsulation. And the 4 -G 3 ′ catalyst of third-generation with dendritic link exhibits excellent catalytic performance, and can be recycled ten times without a significant loss of activity.