Halogen-Bond-Promoted Direct Cross-Coupling of Trifluoromethylated Alkyl Bromides with Coumarins/Quinolinones: Unraveling Trifluoromethyl Effects.

This study introduces a novel approach involving XB-mediated cross-coupling of α-trifluoromethylated alkyl bromides with coumarins and quinolinones under visible light irradiation. Both density functional theory (DFT) calculations and experimental studies converge to suggest that the noncovalent interaction between alkyl bromides and DMAP, intensified by the α-trifluoromethyl group, plays a pivotal role in facilitating this chemoselective reaction.

Catalyst-free decarboxylative cross-coupling of N-hydroxyphthalimide esters with tert-butyl 2-(trifluoromethyl)acrylate and its application.

Here, we demonstrate a practical method toward the facile synthesis of CF3-containing amino acids through visible light promoted decarboxylative cross-coupling of a redox-active ester with tert-butyl 2-(trifluoromethyl)acrylate. The reaction was driven by the photochemical activity of electron donor-acceptor (EDA) complexes that were formed by the non-covalent interaction between a Hantzsch ester and a redox-active ester. The advantages of this protocol are its synthetic simplicity, rich functional group tolerance, and a cost-effective reaction system.

Trifluoromethyl Rhodium-Carbynoid in [2+1+2] Cycloadditions.

Trifluoromethyl cationic carbyne (CF3 C+ :) possessing dual carbene-carbocation behavior emulated as trifluoromethyl metal-carbynoid (CF3 C+ =M) has not been explored yet, and its reaction characteristics are unknown. Herein, a novel α-diazotrifluoroethyl sulfonium salt was prepared and used in Rh-catalyzed three-component [2+1+2] cycloadditions for the first time with commercially available N-fused heteroarenes and nitriles, yielding a series of imidazo[1,5-a] N-heterocycles that are of interest in medicinal chemistry, in which the insertion of trifluoromethyl Rh-carbynoid (CF3 C+ =Rh) into C=N bonds of N-fused heteroarenes was involved. This strategy demonstrates synthetic applications in late-stage modification of pharmaceuticals, construction of CD3 -containing N-heterocycles, gram-scale experiments, and synthesis of phosphodiesterase 10A inhibitor analog. These highly valuable and modifiable imidazo[1,5-a] N-heterocycles exhibit good antitumor activity in vitro, thus demonstrating their potential applications in medicinal chemistry.

Synthesis of Alkylated Polyfluorobenzenes through Decarboxylative Giese Addition of Aliphatic N-Hydroxyphthalimide Esters with Polyfluorostyrene.

Polyfluoroaromatic compounds play crucial roles in medicinal and material science. However, the synthesis of alkylated polyfluoroarenes has been relatively underdeveloped. In this study, we devised a novel decarboxylative coupling reaction between aliphatic N-hydroxyphthalimide esters and polyfluorostyrene, leveraging the photochemical activity of electron donor-acceptor (EDA) complexes. This method offers simple reaction conditions, a broad substrate scope, and excellent functional group tolerance. Furthermore, we have demonstrated the practicality of this protocol through late-stage polyfluoroaryl modification of biologically active molecules using readily available carboxylic acids as starting materials, thus providing an important supplement to the current toolbox for accessing alkylated polyfluoroaryl motifs.

Backbone N-methylation of peptides: Advances in synthesis and applications in pharmaceutical drug development.

Peptide-based drugs have garnered considerable attention in recent years owing to their increasingly crucial role in the treatment of diverse diseases. However, the limited pharmacokinetic properties of peptides have hindered their full potential. One prominent strategy for enhancing the druggability of peptides is N-methylation, which involves the addition of a methyl group to the nitrogen atom of the peptide backbone. This modification significantly improves the stability, bioavailability, receptor binding affinity and selectivity of peptide drug candidates. In this review, we provide a comprehensive overview of the advancements in synthetic methods for N-methylated peptide synthesis, as well as the associated limitations. Moreover, we explore the versatile effects of N-methylation on various aspects of peptide properties. Furthermore, we emphasize the efforts dedicated to N-methylated peptide pharmaceuticals that have successfully obtained marketing approval.

Synthesis of Secondary Trifluoromethylated Alkyl Bromides Using 2-Bromo-3,3,3-trifluoropropene as a Radical Acceptor.

Herein, the first example using commercially available 2-bromo-3,3,3-trifluoropropene (BTP) as a radical acceptor has been reported. Taking advantage of this strategy, a wide range of secondary trifluoromethylated alkyl bromides were synthesized in good to excellent yields with broad functional group tolerance by using redox-active esters as a radical precursor. The practicality of this protocol was further demonstrated by diverse derivations and direct modification of biologically active molecules.

Nickel-Catalyzed Cross-Coupling of Amino-Acid-Derived Alkylzinc Reagents with Alkyl Bromides/Chlorides: Access to Diverse Unnatural Amino Acids.

Unnatural α-amino acids are important synthetic targets in the field of peptide science. Herein we report an efficient, versatile, and straightforward strategy for the synthesis of homophenylalanine derivatives via the nickel-catalyzed Csp3-Csp3 cross-coupling of (fluoro)benzyl bromides/chlorides with natural α-amino-acid-derived alkylzinc reagents. The current protocol features the advantages of a low-cost nickel catalyst system, synthetic convenience, and the tolerance of rich functionality and stereochemistry.

Diazotrifluoroethyl Radical: A CF3-Containing Building Block in [3 + 2] Cycloaddition.

We present herein a visible-light-induced [3 + 2] cycloaddition of a hypervalent iodine(III) reagent with α-ketoacids for the construction of 5-CF3-1,3,4-oxadiazoles that are of importance in medicinal chemistry. The reaction proceeds smoothly without a photocatalyst, metal, or additive under mild conditions. Different from the well-established trifluorodiazoethane (CF3CHN2), the diazotrifluoroethyl radical [CF3C(·)N2], a trifluoroethylcarbyne (CF3CC:) equivalent and an unusual CF3-containing building block, is involved in the present reaction system.

Visible-Light-Induced Palladium-Catalyzed Selective Defluoroarylation of Trifluoromethylarenes with Arylboronic Acids.

Selective functionalization of inactive C(sp3)-F bonds to prepare medicinally interesting aryldifluoromethylated compounds remains challenging. One promising route is the transition-metal-catalyzed cross-coupling through oxidative addition of the C(sp3)-F bond in trifluoromethylarenes (ArCF3), which are ideal precursors for this process due to their ready availability and low cost. Here, we report an unprecedented excited-state palladium catalysis strategy for selective defluoroarylation of trifluoromethylarenes with arylboronic acids. This visible-light-induced palladium-catalyzed cross-coupling proceeds under mild reaction conditions and allows transformation of a variety of arylboronic acids and ArCF3. Preliminary mechanistic studies reveal that the oxidative addition of the C(sp3)-F bond in ArCF3 to excited-state palladium(0) via a single electron transfer pathway is responsible for the C(sp3)-F bond activation.

Using Chlorotrifluoroethane for Trifluoroethylation of (Hetero)aryl Bromides and Chlorides via Nickel Catalysis.

A nickel-catalyzed reductive cross-coupling between industrial chemical CF3CH2Cl and (hetero)aryl bromides and chlorides has been reported. The reaction is synthetically simple without the preparation of arylmetals and exhibits high functional group tolerance. The utility of this protocol has been demonstrated by the late-stage modification of pharmaceuticals, providing a facile route for medicinal chemistry.

Visible light promoted deaminative difluoroalkylation of aliphatic amines with difluoroenoxysilanes.

A visible light promoted deaminative strategy for the difluoroalkylation reaction utilizing pyridinium-activated aliphatic primary amines and difluoroenoxysilane as substrates has been developed. This protocol is characteriazed by its mild reaction conditions and broad substrate scope, which converted a diverse array of amine-containing molecules to the alkyl-CF2COPh products. Moreover, the resulting products can be easily transformed into a vast array of structurally novel and interesting difluoro-containing moieties, therefore providing a facile route for applications in medicinal chemistry and the life sciences.

Iron-Catalyzed Silylation of (Hetero)aryl Chlorides with Et3SiBpin.

To date, the iron-catalyzed construction of C-heteroatom bonds has been less developed due to the difficulty of transmetalation with heteroatom anions and the sluggish reductive elimination. Herein we report an iron-catalyzed method for the silylation of (hetero)aromatic chlorides. It features high efficiency, a broad substrate scope, and excellent functional group compatibility. Moreover, this protocol enables the late-stage silylation of some pharmaceuticals, thus providing an excellent method to access valuable intermediates in medicinal chemistry.

Visible-light Promoted Atom Transfer Radical Addition-Elimination (ATRE) Reaction for the Synthesis of Fluoroalkylated Alkenes Using DMA as Electron-Donor.

Here, we describe a mild, catalyst-free and operationally-simple strategy for the direct fluoroalkylation of olefins driven by the photochemical activity of an electron donor-acceptor (EDA) complex between DMA and fluoroalkyl iodides. The significant advantages of this photochemical transformation are high efficiency, excellent functional group tolerance, and synthetic simplicity, thus providing a facile route for further application in pharmaceuticals and life sciences.

A general and green fluoroalkylation reaction promoted via noncovalent interactions between acetone and fluoroalkyl iodides.

The first example of visible light promoted fluoroalkylation reactions initiated via noncovalent interactions between acetone and fluoroalkyl iodides is presented. The reaction system features synthetic simplicity, mild reaction conditions without any photoredox catalyst, and high functional group tolerance. A wide range of substrate scopes such as alkenes, alkynes and (hetero)arenes were all compatible with the reaction system.

Visible light promoted fluoroalkylation of alkenes and alkynes using 2-bromophenol as a catalyst.

We report a new protocol for the fluoroalkylation of alkenes and alkynes by using 2-bromophenol as a catalyst. This reaction can be tailored for different reaction modes by altering the base and solvent, which feature a wide substrate scope and excellent functional group tolerance with high chemo- and regioselectivities. We further propose a mechanism involving an electron donor-acceptor (EDA) complex.

Organophosphine-Catalyzed Difluoroalkylation of Alkenes.

Atom transfer radical addition and Heck-type reaction between alkenes and ethyl iododifluoroacetate by using organophosphine compounds as catalysts have been developed. The reaction proceeds under mild reaction conditions with excellent functional group tolerance and high chemo- and regioselectivities. Mechanistic study indicates that the reaction might be initiated via noncovalent interactions between an organophosphine catalyst and a carbon-iodine bond.

Palladium-catalyzed cross-coupling of unactivated alkylzinc reagents with 2-bromo-3,3,3-trifluoropropene and its application in the synthesis of fluorinated amino acids.

A palladium-catalyzed cross-coupling of unactivated alkylzinc reagents with 2-bromo-3,3,3-trifluoropropene (BTP) has been developed, which was used as a key step to prepare a series of trifluoromethylated and difluoromethylated amino acids that are of great interest in peptide/protein based chemical biology. The advantages of the synthesis of these fluorinated amino acids are synthetic simplicity and diversity from a simple and readily available key intermediate α-trifluoromethylalkene-containing amino acid, providing a facile route for applications in medicinal chemistry and life science.

Catalyst-free and visible light promoted trifluoromethylation and perfluoroalkylation of uracils and cytosines.

Fluoroalkylated enaminones, such as trifluridine and 5-trifluoromethyluracil, have widespread applications in pharmaceuticals and agrochemicals. Although these kinds of pharmaceutical agent often bear CF3 and perfluoroalkyl motifs in the core structure, access to such analogues typically requires multi-step synthesis. Here, we report a mild, metal-free and operationally simple strategy for the direct perfluoroalkylation of uracils, cytosines and pyridinones through a visible-light induced pathway from perfluoroalkyl iodides. This photochemical transformation features synthetic simplicity, mild reaction conditions without any photoredox catalyst, and high functional group tolerance, providing a facile route for applications in medicinal chemistry.

Visible-Light-Induced Direct Difluoroalkylation of Uracils, Pyridinones, and Coumarins.

An efficient and general method for the synthesis of difluoroalkylated uracils, pyridinones, and coumarins through visible-light-induced reaction with commercial materials is developed. The strategy proceeds with high efficiency under mild reaction conditions and shows excellent functional group compatibility, even toward bromide and hydroxyl group, thus demonstrates high potent application in a late-stage fluoroalkylation. Moreover, the difluoroalkylated products can be further transformed to a diverse variety of difluoroalkylated heterocycles, including molecules of potential biological activity.

Direct olefination of fluorinated benzothiadiazoles: a new entry to optoelectronic materials.

Fluorinated olefin-containing benzothiadiazoles have important applications in optoelectronic materials. Herein, we reported the direct olefination of fluorinated benzothiadiazoles, as catalyzed by palladium. The reaction proceeds under mild reaction conditions and shows high functional-group compatibility. A preliminary study of the properties of the resulting symmetrical and unsymmetrical olefin-containing fluorinated benzothiadiazoles in red-light-emitting dyes has also been conducted.