Nickel-Catalyzed, para-Selective, Radical-Based Alkylation of Aromatic Ketones

Combination of 5-amino-4-nitro-1,2-dihydro-3H-pyrazol-3-one and azine frameworks for insensitive, heat-resistant energetic materials

5-Nitro-1,2,4-triazol-3-one (NTO) is an important insensitive and high-energy aromatic ketone compound in energetic materials. However, its relatively low thermostability (Td: 236.0 °C) limits its application in heat-resistant energetic materials. In this study, we utilized an NTO analogue (5-amino-4-nitro-1,2-dihydro-3H-pyrazol-3-one, ANPO) to prepare a series of new heat-resistant energetic compounds, NPX-10-NPX-14, whose thermal decomposition temperatures range from 311 °C to 386 °C, around 75-150 °C higher than that of NTO. At the same time, these five new heat-resistant energetic compounds exhibited low impact sensitivity (IS > 50 J) and friction sensitivity (FS > 360 N), such as NTO, demonstrating their potential as insensitive, heat-resistant energetic materials. In addition, the effects of structures on sensitivity and thermal stability are studied using quantum chemical methods. This work is expected to prompt further research on energetic pyrazolone in molecular design and offers guidance for the development of new heat-resistant energetic materials.

para-Selective, Direct C(sp2)-H Alkylation of Electron-Deficient Arenes by the Electroreduction Process

Direct para-selective C(sp²)-H alkylation of electron-deficient arenes based on the electroreduction-enabled radical addition of alkyl bromides has been developed under mild conditions. In the absence of any metals and redox agents, the simple electrolysis system tolerates a variety of primary, secondary, and tertiary alkyl bromides and behaves as an important complement to the directed alkylation of the C(sp²)-H bond and the classic Friedel-Crafts alkylation. This electroreduction process provides a more straightforward, environmentally benign, and effective alkylation method for electron-deficient arenes.

Regioselective Friedel-Crafts Acylation Reaction Using Single Crystalline and Ultrathin Nanosheet Assembly of Scrutinyite-SnO2

Peculiar physicochemical properties of two-dimensional (2D) nanomaterials have attracted research interest in developing new synthetic technology and exploring their potential applications in the field of catalysis. Moreover, ultrathin metal oxide nanosheets with atomic thickness exhibit abnormal surficial properties because of the unique 2D confinement effect. In this work, we present a facile and general approach for the synthesis of single crystalline and ultrathin 2D nanosheets assembly of scrutinyite-SnO₂ through a simple solvothermal method. The structural and compositional characterization using X-ray diffraction (Rietveld refinement analysis), high-resolution transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and so on reveal that the as-synthesized 2D nanosheets are ultrathin and single crystallized in the scrutinyite-SnO₂ phase with high purity. The ultrathin SnO₂ nanosheets show predominant growth in the [011] direction on the main surface having a thickness of ca. 1.3 nm. The SnO₂ nanosheets are further employed for the regioselective Friedel-Crafts acylation to synthesize aromatic ketones that have potential significance in chemical industry as synthetic intermediates of pharmaceuticals and fine chemicals. A series of aromatic substrates acylated over the SnO₂ nanosheets have afforded the corresponding aromatic ketones with up to 92% yield under solvent-free conditions. Comprehensive catalytic investigations display the SnO₂ nanosheet assembly as a better catalytic material compared to the heterogeneous metal oxide catalysts used so far in the view of its activity and reusability in solvent-free reaction conditions.

Recent Advances in Transition-Metal-Catalyzed Selective C–H Alkoxycarbonyldifluoromethylation Reactions of Aromatic Substrates

Fluorine is well-known as a very special element. Approximately 30% of agrochemicals and 20% of all drugs contain fluorine; most of those compounds have unique functions in biochemistry, pharmacy, and bioscience and those containing alkoxycarbonyldifluoromethyl functional groups often have irreplaceable roles. Therefore, the selective introduction of alkoxycarbonyldifluoromethylated functional groups into various aromatic substrates has significant practical application. This review describes recent advances in selective alkoxycarbonyldifluoromethylation of aromatic substrates by using different catalytic strategies (cyclometalated ruthenium complex, transient regulating and visible-light-induced strategies).

1 Introduction

2 para-C–H Alkoxycarbonyldifluoromethylation of Aromatic Derivatives

2.1 Ruthenium Catalysis

2.2 Palladium Catalysis

2.3 Visible-Light Catalysis

2.4 Iron Catalysis

3 meta-C–H Alkoxycarbonyldifluoromethylation of Aromatic Derivatives

3.1 Ruthenium Catalysis

3.2 Palladium Catalysis

4 The Influence of Transition Metals and Directing Groups on Site Selectivity of Alkoxycarbonyldifluoromethylation

4.1 The Influence of Directing Groups on the Site Selectivity of Alkoxycarbonyldifluoromethylation

4.2 The Influence of Transition Metals on the Site Selectivity of Alkoxycarbonyldifluoromethylation

5 Conclusions

Ligand Promoted Olefination of Anilides for Indirectly Introducing Fluorinated Functional Groups via Palladium Catalyst

We report a palladium-catalyzed, ligand promoted, C-H fluorine-containing olefination of anilides with 4-bromo-3,3,4,4-tetrafluorobutene as the fluorinated reagent, which has a potential transformation into other compounds due to its -CF₂CF₂Br functional group. -CF₂CF₂H was obtained by using the mild reducing agent sodium borohydride. Bioactive compounds such as aminoglutethimide derivative and propham were well-tolerated in this reaction, both of which highlight the synthetic importance of this method.