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 H2 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 H2. 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 H2 pressure. The formation of a CuxPdy 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.
Cross-linked cyclodextrins bimetallic nanocatalysts: Applications in microwave-assisted reductive aminations / Gaudino, E. C.; Acciardo, E.; Tabasso, S.; Manzoli, M.; Cravotto, G.; Varma, R. S.. - In: MOLECULES. - ISSN 1420-3049. - 25:2(2020), p. 410.
|Titolo:||Cross-linked cyclodextrins bimetallic nanocatalysts: Applications in microwave-assisted reductive aminations|
|Data di pubblicazione:||2020|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.3390/molecules25020410|
|Appare nelle tipologie:||1.1 Articolo in rivista|