Robby Vroemans

Nature Chemistry, Published online: 13 January 2022; doi:10.1038/s41557-021-00846-4

This review describes the recent developments of dual catalysis in rhodium (II) carbenoid chemistry, where rhodium is cooperatively working with a second transition metal (Sc/Pd/Ag/Au) or organocatalyst. The redox compatibility, turnover pathways, and the generation of unique rhodium-bound zwitterionic intermediates make rhodium an attractive partner for dual catalysis reactions to enable new transformations.

Abstract

Dual catalysis represents an alternative archetype in carbene chemistry that surpasses traditional single catalyst systems. By employing dual catalyst systems, one can improve the efficiency of existing reactions and enable new chemical transformations. Reactions involving dual synergistic catalysis are increasingly valuable as they offer convenient strategies for synthesizing challenging quaternary carbon centers and bioactive core structures. This review article focuses on trapping diazo-derived, rhodium (II) zwitterionic intermediates with varying electrophiles such as Michael acceptors, alkynes, π-allyl Pd(II) complexes, and the Nicholas intermediate.

Synthesis
DOI: 10.1055/s-0040-1719864

The introduction of easy-to-handle SO2 surrogates has transformed the field of sulfur chemistry, enabling methodologies utilizing SO2 to be carried out without specialized apparatus, and paving the way for the development of new procedures. This review highlights some of the varied and significant developments associated with one of the most prominent SO2 surrogates: DABSO.1 Introduction2 DABSO3 Reactions with Nucleophilic Reagents4 Metal-Catalyzed Reactions4.1 Palladium-Catalyzed Reactions4.2 Other Transition-Metal Catalysis5 Radical Reactions5.1 Aryldiazonium Salts5.2 Other Aryl Radical Precursors5.3 Alkyl Radical Precursors6 Conclusion
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Article in Thieme eJournals:
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Bono VOCs: Volatile organic compounds (VOCs) are detrimental to the environment and human health and must be eliminated. Precious metal catalysts are highly active for oxidation of VOCs, but their rarity and high price limits large-scale application. Supported metal single-atom catalysts (SACs) have high atom efficiency and can mitigate such limitations. This Review summarizes recent advances in the use of SACs for oxidation of VOCs.

Abstract

Volatile organic compounds (VOCs) are detrimental to the environment and human health and must be eliminated before discharging. Oxidation by heterogeneous catalysts is one of the most promising approaches for the VOCs abatement. Precious metal catalysts are highly active for the catalytic oxidation of VOCs, but they are rare and their high price limits large-scale application. Supported metal single-atom catalysts (SACs) have a high atom efficiency and provide the possibility to circumvent such limitations. This Review summarizes recent advances in the use of metal SACs for the complete oxidation of VOCs, such as benzene, toluene, formaldehyde, and methanol, as well as aliphatic and Cl- and S-containing hydrocarbons. The structures of the metal SACs used and the reaction mechanisms of the VOC oxidation are discussed. The most widely used SACs are noble metals supported on oxides, especially on reducible oxides, such as Mn₂O₃ and TiO₂. The reactivity of most SACs is related to the activity of surface lattice oxygen of the oxides. Furthermore, several metal SACs show better reactivity and improved S and Cl resistance than the corresponding nanocatalysts, indicating that SACs have potential for application in the oxidation of VOCs. The deactivation and regeneration mechanisms of the metal SACs are also summarized. It is concluded that the application of metal SACs in catalytic oxidation of VOCs is still in its infancy. This Review aims to elucidate structure–performance relationships and to guide the design of highly efficient metal SACs for the catalytic oxidation of VOCs.

A coordination engineering strategy based on a p-block In single-atom catalyst with N,S-dual first coordination and B second coordination on hollow carbon rods (In SAs/NSBC) has been developed. DFT results and electrochemical analysis show a superior 2 e⁻ oxygen reduction performance of the In SAs/NSBC catalyst in alkaline and neutral solutions, which is ascribed to synergistic effects between first-coordinated N/S, second-coordinated B, and single In atoms.

Abstract

The in-depth understanding of local atomic environment–property relationships of p-block metal single-atom catalysts toward the 2 e⁻ oxygen reduction reaction (ORR) has rarely been reported. Here, guided by first-principles calculations, we develop a heteroatom-modified In-based metal–organic framework-assisted approach to accurately synthesize an optimal catalyst, in which single In atoms are anchored by combined N,S-dual first coordination and B second coordination supported by the hollow carbon rods (In SAs/NSBC). The In SAs/NSBC catalyst exhibits a high H₂O₂ selectivity of above 95 % in a wide range of pH. Furthermore, the In SAs/NSBC-modified natural air diffusion electrode exhibits an unprecedented production rate of 6.49 mol peroxide g_catalyst ⁻¹ h⁻¹ in 0.1 M KOH electrolyte and 6.71 mol peroxide g_catalyst ⁻¹ h⁻¹ in 0.1 M PBS electrolyte. This strategy enables the design of next-generation high-performance single-atom materials, and provides practical guidance for H₂O₂ electrosynthesis.

A nickel-catalyzed desymmetric reductive cyclization/coupling reaction of 1,6-dienes and alkyl bromides is reported. A chiral tertiary alcohol and a quaternary stereocenter are constructed by a single operation with excellent diastereoselectivity and high enantioselectivity.

Abstract

We have developed a nickel-catalyzed desymmetric reductive cyclization/coupling of 1,6-dienes. The reaction provides an efficient method for constructing a chiral tertiary alcohol and a quaternary stereocenter by a single operation. The method has excellent diastereoselectivity and high enantioselectivity, a broad substrate scope, as well as good tolerance of functional groups. Preliminary mechanism studies show that alkyl nickel(I) species are involved in the reaction.

Synthesis
DOI: 10.1055/s-0041-1737326

Pd-catalyzed direct arylation of 2-alkylthiazoles is a well-known reaction affording the corresponding 2-alkyl-5-arylthiazoles in very high yields. Conversely, the reactivity of 2-alkoxythiazoles has not been described yet. Herein, we report conditions for the Pd-catalyzed regioselective C5-arylation of 2-alkoxythiazoles. Moreover, we also found reaction conditions leading to 3-alkyl-5-arylthiazol-2(3H)-ones via a one-pot direct arylation with an O- to N-alkyl migratory rearrangement. The judicious choice of reaction temperature and time allows control over the selectivity of the reaction. In general, at 100 °C, 2-alkoxy-5-arylthiazoles were the major products, whereas, at 120 °C with a longer reaction time, 3-alkyl-5-arylthiazol-2(3H)-ones were obtained with good selectivities. The arylation reaction is promoted by a ligand-free air-stable palladium catalyst and a simple and inexpensive base, without oxidant or further additives, and tolerates a variety of useful substituents on the aryl bromide and also heteroaryl bromides.
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Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

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A new synthetic route towards benzimidazo[2,1-b]quinazolin-12-ones has been developed, which relies on the Pd-catalyzed intramolecular aminocarbonylation of N-(2-bromophenyl)-1H-benzimidazol-2-amines. Using near stoichiometric amounts of ¹³CO, isotopically labelled benzimidazo[2,1-b]quinazolin-12-ones were synthesized.

Abstract

A carbonylative route towards the synthesis of benzimidazo[2,1-b]quinazolin-12-ones was developed. The key step in this strategy consists of an intramolecular carbonylative lactam formation, starting from N-(2-bromophenyl)-1H-benzimidazol-2-amines. These precursor molecules were synthesized by two different methods to introduce a variety of substituents on the aromatic ring systems. Interestingly, only near-stoichiometric amounts of carbon monoxide were required in the ring-closing aminocarbonylation reaction, rendering the developed strategy also suitable for late-stage ¹³C-isotopic labelling.

Beilstein J. Org. Chem. 2022, 18, 86–88. doi:10.3762/bjoc.18.8

Nature, Published online: 05 January 2022; doi:10.1038/d41586-022-00007-8