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Cross-Linked Cyclodextrins Bimetallic Nanocatalysts: Applications in Microwave-Assisted Reductive Aminations.
- Source :
-
Molecules (Basel, Switzerland) [Molecules] 2020 Jan 19; Vol. 25 (2). Date of Electronic Publication: 2020 Jan 19. - Publication Year :
- 2020
-
Abstract
- The optimization of sustainable protocols for reductive amination has been a lingering challenge in green synthesis. In this context, a comparative study of different metal-loaded cross-linked cyclodextrins (CDs) were examined for the microwave (MW)-assisted reductive amination of aldehydes and ketones using either H <subscript>2</subscript> or formic acid as a hydrogen source. The Pd/Cu heterogeneous nanocatalyst based on Pd (II) and Cu (I) salts embedded in a β-CD network was the most efficient in terms of yield and selectivity attained. In addition, the polymeric cross-linking avoided metal leaching, thus enhancing the process sustainability; good yields were realized using benzylamine under H <subscript>2</subscript> . These interesting findings were then applied to the MW-assisted one-pot synthesis of secondary amines via a tandem reductive amination of benzaldehyde with nitroaromatics under H <subscript>2</subscript> pressure. The formation of a Cu <subscript>x</subscript> Pd <subscript>y</subscript> alloy under reaction conditions was discerned, and a synergic effect due to the cooperation between Cu and Pd has been hypothesized. During the reaction, the system worked as a bifunctional nanocatalyst wherein the Pd sites facilitate the reduction of nitro compounds, while the Cu species promote the subsequent imine hydrogenation affording structurally diverse secondary amines with high yields.
Details
- Language :
- English
- ISSN :
- 1420-3049
- Volume :
- 25
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Molecules (Basel, Switzerland)
- Publication Type :
- Academic Journal
- Accession number :
- 31963796
- Full Text :
- https://doi.org/10.3390/molecules25020410