Mechanochemical Conversion of Aromatic Amines to Aryl Trifluoromethyl Ethers

Mechanochemical synthesis of aromatic ketones: pyrylium tetrafluoroborate mediated deaminative arylation of amides

A new method has been introduced that is able to tackle the complexities of N-C(O) activation in amide moieties through utilization of pyrylium tetrafluoroborate in a mechanochemical setting, where amide bonds undergo activation and subsequent conversion to biaryl ketones. Due to the employment of a mechanochemical setting, the reaction conforms to green chemistry principles, offering an environmentally friendly approach to traditional amide derivatization techniques that rely on transition metals to achieve further functionalization.

Indium Promotes Direct Sulfonamidation of Unactivated Alcohols

An improved protocol has been developed for the direct sulfonamidation of unactivated alkyl alcohols using In(OTf)3 as a Lewis acid catalyst. Although the established methods using Lewis or Brønsted acids have been well-studied for the direct functionalization of alcohols, their substrate scope mainly focuses on the π-activated alcohols. In this reaction, unactivated aliphatic alcohols were evaluated and afforded the desired sulfonamide products with good to excellent yields.

Unexpected side reactions dominate the oxidative transformation of aromatic amines in the Co(II)/peracetic acid system

Aromatic amines (AAs), ubiquitous in industrial applications, pose significant environmental hazards due to their resistance to conventional wastewater treatments. Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have been proposed as effective strategies for addressing persistent AA contaminants. While the organic radicals generated in these systems are believed to be selective and highly oxidative, acetate residue complicates the evaluation of AA removal efficiency. In this work, we explored transformation pathways of AAs in a representative Co(II)-catalyzed PAA system, revealing five side reactions (i.e. nitrosation, nitration, coupling, dimerization, and acetylation) that yield 17 predominantly stable and toxic by-products. The dominant reactive species was demonstrated as Co-OOC(O)CH3, which hardly facilitated ring-opening reactions. Our findings highlight the potential risks associated with PAA-based AOPs for AA degradation and provide insights into selecting suitable catalytic systems aimed at efficient and by-product-free degradation of pollutants containing aromatic -NH2.

Skeletal rearrangement through photocatalytic denitrogenation: access to C-3 aminoquinolin-2(1H)-ones

The addition of an amine group to a heteroaromatic system is a challenging synthetic process, yet it is an essential one in the development of many bioactive molecules. Here, we report an alternative method for the synthesis of 3-amino quinolin-2(1H)-one that overcomes the limitations of traditional methods by editing the molecular skeleton via a cascade C-N bond formation and denitrogenation process. We used TMSN3 as an aminating agent and a wide variety of 3-ylideneoxindoles as synthetic precursors for the quinolin-2(1H)-one backbone, which demonstrates remarkable tolerance of sensitive functional groups. The control experiments showed that the triazoline intermediate plays a significant role in the formation of the product. The spectroscopic investigation further defined the potential reaction pathways.

Mechanochemical arylative detrifluoromethylation of trifluoromethylarenes

The stoichiometric defluorinative functionalization of ArCF3 is a conceptually appealing research target. It enables the challenging late-stage functionalization of CF3-containing aromatic molecules and contributes to the remedy of environmental risks resulting from the accumulation of relatively inert ArCF3-containing molecules. Similarly, Ar-CN bond features limit their utilization in cross-coupling reactions. Thus, the employment of benzonitriles in decyanative Suzuki-Miyaura type coupling remains in high demand in the field of C-C bond formation. Herein, we report mechanochemically induced and ytterbium oxide (Yb2O3)-mediated defluorinative cyanation of trifluoromethylarenes. In addition, we describe a facile mechanochemically facilitated and nickel-catalyzed decyanative arylation of benzonitriles to access biphenyls. Combining both processes in a one-pot multicomponent protocol to achieve a concise direct arylative detrifluoromethylation of ArCF3 is described herein. This work is the first hitherto realization of C-C coupling with CF3 as a formal leaving group.

Synthesis and Biological Evaluation of a Library of Sulfonamide Analogs of Memantine to Target Glioblastoma

A library of 34 lipophilic sulfonamides based upon the memantine core has been synthesized to identify potential drug candidates to cross the blood-brain barrier and target glioblastoma. The library was screened for in vitro activity against 4 mammalian cell lines, including U-87 (glioblastoma). Additional synthetic variation of the active compounds has validated the importance of specific regions of the pharmacophore, with the sulfonamide functionality and S-aryl unit displaying the most significant impact. In silico investigations suggest the active compounds might target DDR1 or RET proteins. The investigation has resulted in several compounds that warrant further development for lead optimization.

Bio-Inspired Deaminative Hydroxylation of Aminoheterocycles and Electron-Deficient Anilines

Among the tools available to chemists for drug design of bioactive compounds, the bioisosteric replacement of atoms or groups of atoms is the cornerstone of modern strategies. Despite the undeniable interest in amino-to-hydroxyl interchange, enzymatic deaminative hydroxylation remains unmatched. Herein, we report a user friendly and safe procedure to selectively convert aminoheterocycles to their hydroxylated analogues by means of a simple pyrylium tetrafluoroborate salt. The hydroxylation step relies on a Lossen-type rearrangement under mild conditions thus avoiding the use of strong hydroxide bases. In addition to biorelevant heterocycles, the deaminative hydroxylation of electron-deficient anilines was also demonstrated. Finally, mechanistic experiments allowed the identification of the key intermediates, thus unveiling a rather unusual mechanism for this formal aromatic substitution.

Mechanochemical Defluorinative Arylation of Trifluoroacetamides: An Entry to Aromatic Amides

The amide bond is prominent in natural and synthetic organic molecules endowed with activity in various fields. Among a wide array of amide synthetic methods, substitution on a pre-existing (O)C-N moiety is an underexplored strategy for the synthesis of amides. In this work, we disclose a new protocol for the defluorinative arylation of aliphatic and aromatic trifluoroacetamides yielding aromatic amides. The mechanochemically induced reaction of either arylboronic acids, trimethoxyphenylsilanes, diaryliodonium salts, or dimethyl(phenyl)sulfonium salts with trifluoroacetamides affords substituted aromatic amides in good to excellent yields. These nickel-catalyzed reactions are enabled by C-CF₃ bond activation using Dy₂O₃ as an additive. The current protocol provides versatile and scalable routes for accessing a wide variety of substituted aromatic amides. Moreover, the protocol described in this work overcomes the drawbacks and limitations in the previously reported methods.