Carbon Nanotube–Ruthenium Hybrids for the Partial Reduction of 2‐Nitrochalcones: Easy Access to Quinoline N‐Oxides

Abstract

A ruthenium–carbon nanotube nanohybrid was employed as a catalyst in the tandem transformation of nitrochalcones into quinoline N‐oxides. Partial reduction of the nitro group to a hydroxylamine, followed by in situ intramolecular condensation to the carbonyl afforded the quinoline‐N‐oxides in satisfactory to good yields. Reduction of the nitro group was selective and independent of changes in the reaction conditions. Highlights of this method include a very low catalyst loading relative to that required for conventional methods for the synthesis of quinoline N‐oxides and mild reaction conditions.

Modified Nanocarbons for Catalysis

“…Doris et al . also reported 85‐Ru , endowed with ruthenium nanoparticles, which has been used as catalyst for promoting the tandem reaction of nitrochalcones into quinoline N ‐oxides through the partial reduction of the nitro group to a hydroxylamine, followed by in situ intramolecular condensation to the carbonyl group (Scheme ) . The catalyst has been used in 0.4 mol % and resulted recyclable for 5 cycles with no losses in activity.…”

Cobalt oxide–carbon nanocatalysts with highly enhanced catalytic performance for the green synthesis of nitrogen heterocycles through the Friedländer condensation

“…4 However, the application of nanostructured carbon forms such as carbon nanotubes (CNTs) and more recently carbon aerogels 5 are issues of interest and continuously growing. For instance, Pd/Co nanoparticles supported on multi-walled CNTs have recently reported in the microwave-assisted efficient synthesis of substituted tetrazoles 6 , Cu loadings on Ni/carbon nanotubes catalysts in the hydrodeoxygenation reaction of guaiacol 7 , and RuCNT nanohybrid in the selective catalytic reduction of nitrochalcones to quinoline N-oxides 8 . AuCNTs have been also found to be interesting catalysts in diverse chemical transformations such as oxidation reaction of silanes 9 , alcohols 10 , and phenols 11 , reductive amination 12 deoxygenation of amine N-oxides 13 , aldehydes N-formylation 14 and in the synthesis of quinoxalines 15 .…”

Carbocatalytic Activity of Graphene Oxide in Organic Synthesis

“…It was reasoned that the reactant molecules were first adsorbed on the CNT surface via π-interactions next to basic oxygen moieties, which facilitated dehydrogenation with concomitant formation of surface hydroxyl groups [19]. Taking advantage of surface modification techniques, various nanoparticle as well as molecular catalysts could be anchored on carbon nanotubes [21] (Figure 1).…”