One-pot aerobic oxidative sulfonamidation of aromatic thiols with ammonia by a dual-functional β-MnO₂ nanocatalyst

Abstract

High-surface-area β-MnO2 nanoparticles exhibited high activity for the one-pot oxidative sulfonamidation of thiols to sulfonamides using O2 and NH3.

Template-Free Synthesis of Mesoporous β-MnO2 Nanoparticles: Structure, Formation Mechanism, and Catalytic Properties

“…In contrast to those on α, γ, ε, and δ-MnO 2 , − ,,, studies on the controlled synthesis of β-MnO 2 with a high surface area have still been limited because the activation barrier for the transformation of other manganese oxides to β-MnO 2 has been reported to be high, although β-MnO 2 is a thermodynamically stable phase among the MnO 2 polymorphs. ,, Therefore, the hydrothermal synthesis of β-MnO 2 typically requires high reaction temperatures (150–180 °C) or long reaction times (12–48 h), which result in a significant increase in the β-MnO 2 particle size and low surface areas (3–35 m 2 g –1 ). ,,,, In contrast, soft- and hard-template methods for the synthesis of mesoporous β-MnO 2 materials with high surface areas (68–195 m 2 g –1 ) have been reported, despite the need for multistep procedures or the utilization of organic and inorganic templates or organic reductants. − ,, During the course of our investigations on catalytic biomass conversion and aerobic oxidation, − we have recently reported that β-MnO 2 can act as the most effective oxidation catalyst for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) as a bioplastic monomer on the basis of combined computational and experimental studies . The successful synthesis of the high-surface-area β-MnO 2 nanoparticles by the simple calcination of precursors prepared from NaMnO 4 and MnSO 4 at 400 °C has resulted in significant improvement of the catalytic performance in comparison with β-MnO 2 synthesized under hydrothermal conditions ( β - MnO 2 - HT ) (Figures and S1).…”

Aerobic oxidative CC bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst

“…Therefore, we have focused on the liquid-phase catalysis of hexagonal perovskites with unique face-sharing octahedral units based on high valency metal species. During the course of our investigation on crystalline first-row metal oxide catalysts, [12][13][14][15][16][17] we have successfully synthesized various hexagonal perovskite nanoparticle catalysts for the liquid phase selective oxidation of various organic substrates with O 2 as the sole oxidant. [15][16][17] In particular, high valency iron-containing BaFeO 3−δ was found to act as an efficient heterogeneous catalyst for the aerobic oxidation of alkanes to the corresponding alcohols and ketones, in sharp contrast to Fe 3+ /Fe 2+ oxides.…”

Direct synthesis of sulfenamides, sulfinamides, and sulfonamides from thiols and amines

“…Very recently, the research group of Kamata and Hara explored the catalytic application of dual-functional high-surface-area β-MnO 2 (β-MnO 2 -HS) nanoparticles for the direct sulfonylation of ammonia with thiols to synthesize primary sulfonamides. 43 Various aromatic and heteroaromatic thiols 39 have been reacted with aqueous NH 3 in the presence of a catalytic amount of β-MnO 2 -HS under O 2 atmosphere to give (hetero)aryl sulfonamides 40 in moderate to high yields ( Scheme 21 ). The reaction works better with electron rich than with electron poor substituents on the aryl thiols (88% yield for 4-OMe-substituted substrate compared to 58% for the 4-nitro derivative).…”