38581-14-5

Upstream product

• 823-96-1 Trimethylboroxine 
• 1126-00-7 1-phenylpyrazole 
• 288-13-1 NH-pyrazole 
• 443-88-9 2-fluoro-m-xylene 
• 108-38-3 m-xylene 

Relevant academic research and scientific papers

Unveiling Potent Photooxidation Behavior of Catalytic Photoreductants

We describe a photocatalytic system that reveals latent photooxidant behavior from one of the most reducing conventional photoredox catalysts, N-phenylphenothiazine (PTH). This aerobic photochemical reaction engages difficult to oxidize feedstocks, such as benzene, in C(sp2)-N coupling reactions through direct oxidation. Mechanistic studies are consistent with activation of PTH via photooxidation and with Lewis acid cocatalysts scavenging inhibitors inextricably formed in this process.

Dehydrogenative Azolation of Arenes in a Microflow Electrochemical Reactor

The electrochemical synthesis of aryl azoles was performed for the first time in a microflow reactor. The reaction relies on the anodic oxidation of the arene partners making these substrates susceptible for C-H functionalization with azoles, thus requiring no homogeneous transition-metal-based catalysts. The synthetic protocol benefits from the implementation of a microflow setup, leading to shorter residence times (10 min), compared to previously reported batch systems. Various azolated compounds (22 examples) are obtained in good to excellent yields.

Mechanochemical Solvent-Free Catalytic C?H Methylation

The mechanochemical, solvent-free, highly regioselective, rhodium-catalyzed C?H methylation of (hetero)arenes is reported. The reaction shows excellent functional-group compatibility and is demonstrated to work for the late-stage C?H methylation of biologically active compounds. The method requires no external heating and benefits from considerably shorter reaction times than previous solution-based C?H methylation protocols. Additionally, the mechanochemical approach is shown to enable the efficient synthesis of organometallic complexes that are difficult to generate conventionally.

Cobalt-catalysed C–H methylation for late-stage drug diversification

The magic methyl effect is well acknowledged in medicinal chemistry, but despite its significance, accessing such analogues via derivatization at a late stage remains a pivotal challenge. In an effort to mitigate this major limitation, we here present a strategy for the cobalt-catalysed late-stage C–H methylation of structurally complex drug molecules. Enabling broad applicability, the transformation relies on a boron-based methyl source and takes advantage of inherently present functional groups to guide the C–H activation. The relative reactivity observed for distinct classes of functionalities were determined and the sensitivity of the transformation towards a panel of common functional motifs was tested under various reaction conditions. Without the need for prefunctionalization or postdeprotection, a diverse array of marketed drug molecules and natural products could be methylated in a predictable manner. Subsequent physicochemical and biological testing confirmed the magnitude with which this seemingly minor structural change can affect important drug properties. [Figure not available: see fulltext.]

Nucleophilic aromatic substitution of unactivated fluoroarenes enabled by organic photoredox catalysis

Nucleophilic aromatic substitution (SNAr) is a classical reaction with well-known reactivity toward electron-poor fluoroarenes. However, electron-neutral and electron-rich fluoro(hetero)arenes are considerably underrepresented. Herein, we present a method for the nucleophilic defluorination of unactivated fluoroarenes enabled by cation radical-accelerated nucleophilic aromatic substitution. The use of organic photoredox catalysis renders this method operationally simple under mild conditions and is amenable to various nucleophile classes, including azoles, amines, and carboxylic acids. Select fluorinated heterocycles can be functionalized using this method. In addition, the late-stage functionalization of pharmaceuticals is also presented. Computational studies demonstrate that the site selectivity of the reaction is dictated by arene electronics.

Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication

Visible-light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions. Here, these two modalities are combined in an electrophotocatalytic oxidation platform. This chemistry employs a trisaminocyclopropenium (TAC) ion catalyst, which is electrochemically oxidized to form a cyclopropenium radical dication intermediate. The radical dication undergoes photoexcitation with visible light to produce an excited-state species with oxidizing power (3.33 V vs. SCE) sufficient to oxidize benzene and halogenated benzenes via single-electron transfer (SET), resulting in C?H/N?H coupling with azoles. A rationale for the strongly oxidizing behavior of the photoexcited species is provided, while the stability of the catalyst is rationalized by a particular conformation of the cis-2,6-dimethylpiperidine moieties.