Carbon Nanotube–Gold Nanohybrid Catalyzed N‐Formylation of Amines by using Aqueous Formaldehyde

Abstract

The N‐formylation of a variety of primary and secondary amines by using aqueous formaldehyde at room temperature in open air affords the corresponding formamides in excellent yield under the catalytic influence of a gold–carbon nanotube nanohybrid. The reaction is also marked by excellent chemoselectivity, low catalyst loading, and recyclability of the catalyst.

Discovery and Characterization of 2‐(Cyclopropanesulfonamido)‐N‐(2‐ethoxyphenyl)benzamide, ML382: a Potent and Selective Positive Allosteric Modulator of MrgX1

“…Although the catalytic activity of AuNPs with a variety of supports has been extensively investigated for over a decade,11 carbon nanotube (CNT)‐supported AuNPs have emerged as highly efficient and recyclable heterogeneous catalysts only recently 12–16. In this context, we have exploited the robustness of CNTs and their ability to stabilize a metal’s transient higher oxidation states17 in the development of an AuCNT nanohybrid in which Au nanoparticles were stabilized by a polyanionic–polycationic two‐layer assembly around CNTs (Figure 1).…”

“…In this context, we have exploited the robustness of CNTs and their ability to stabilize a metal’s transient higher oxidation states17 in the development of an AuCNT nanohybrid in which Au nanoparticles were stabilized by a polyanionic–polycationic two‐layer assembly around CNTs (Figure 1). The exceptional catalytic efficiency of this nanohybrid in comparison to other supported and colloidal AuNPs has been demonstrated in the oxidation of silanes,12 alcohols,13 and phenols,14 and in the reductive amination15 and N‐formylation of aldehydes 16. Building on this work, we desired to develop an efficient methodology for the synthesis of quinoxalines from 1,2‐ketoalcohols and 1,2‐diols by using our AuCNT catalyst under simple and mild conditions.…”

Synthesis of Formate Esters and Formamides Using an Au/TiO2-Catalyzed Aerobic Oxidative Coupling of Paraformaldehyde

“…Shi and colleagues [ 29 ] have used a homemade Au/Al 2 O 3 catalyst, which operates at room temperature and 1 atm O 2 pressure and requires a base, such as NaOH in H 2 O as a solvent. Doris and Namboothiri [ 30 ] used a carbon nanotube-Au nanohybrid as a catalyst, and aqueous toluene as a solvent, while NaOH is also required. Prior to these reports, Sakurai’s group had shown an analogous NaOH-promoted coupling using Au nanoclusters stabilized by poly( N -vinyl-2-pyrrolidone) as a catalyst [ 31 ].…”

Supramolecular Assembly of Gold Nanoparticles on Carbon Nanotubes: Application to the Catalytic Oxidation of Hydroxylamines

“…Although gold has long been regarded as a poor catalytic metal, its nanosized forms [ 8 ], including supported ones [ 9 , 10 ], have recently been shown to be able to catalyze a wide array of chemical transformations. Our CNT-gold catalyst was built using a layer-by-layer approach that was adapted from our previous work [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ]. Carbon nanotubes were first dispersed in an aqueous solution by ultrasonication in the presence of an amphiphilic nitrilotriacetic-diyne (DANTA) surfactant.…”