An N-Trifluoromethylation/Cyclization Strategy for Accessing Diverse N-Trifluoromethyl Azoles from Nitriles and 1,3-Dipoles

Photoredox-Catalyzed Trifluoromethylamination of Alkenes with Concomitant Introduction of a Quinoxalin-2(1H)-one Moiety

A photoredox-catalyzed strategy for the difunctionalization of alkenes with quinoxalin-2(1H)-ones and N-CF3 hydroxylamine reagents was developed. This reaction was carried out under photoirradiation conditions, affording the corresponding three-component coupling products in moderate to high yields with excellent regioselectivity. It provides a new protocol to access valuable quinoxalin-2(1H)-one derivatives containing a N-CF3 group.

Nitrogen-Based Organofluorine Functional Molecules: Synthesis and Applications

Fluorine and nitrogen form a successful partnership in organic synthesis, medicinal chemistry, and material sciences. Although fluorine-nitrogen chemistry has a long and rich history, this field has received increasing interest and made remarkable progress over the past two decades, driven by recent advancements in transition metal and organocatalysis and photochemistry. This review, emphasizing contributions from 2015 to 2023, aims to update the state of the art of the synthesis and applications of nitrogen-based organofluorine functional molecules in organic synthesis and medicinal chemistry. In dedicated sections, we first focus on fluorine-containing reagents organized according to the type of fluorine-containing groups attached to nitrogen, including N-F, N-RF, N-SRF, and N-ORF. This review also covers nitrogen-linked fluorine-containing building blocks, catalysts, pharmaceuticals, and agrochemicals, underlining these components' broad applicability and growing importance in modern chemistry.

O-Trifluoromethylation of ketones: an alternative straightforward route to alkenyl trifluoromethyl ethers

Here we report an unprecedented O-trifluoromethylation of ketones using chloro(phenyl)trifluoromethyl-λ3-iodane (CPTFI). Our method provides a new strategy for the facile synthesis of various synthetically valuable alkenyl trifluoromethyl ethers, particularly those CF3O-substituted terminal alkenes and cyclic alkenes that have been elusive until now, from simple aromatic, aliphatic, and cyclic ketones. The success of this reaction is attributed to the full utilization of the multifunctionality of CPTFI: (1) its strong Lewis acid activation ability, which enables weak nucleophiles such as Cl anions to attack the carbonyl group; (2) its bifunctionality, which allows for the introduction of CF3 and Cl into the carbonyl group in one step, thus enabling the obtainment of alkenyl trifluoromethyl ethers by further removal of HCl. The further transformation in the synthesis of CF3O-cyclopropanes, which were previously largely unexplored, reveals the significant potential of alkenyl trifluoromethyl ethers as valuable CF3O-containing building blocks in the discovery of innovative materials, pharmaceuticals, and agrochemicals.

Modular Synthesis of Monofluorinated 1,2,4-Triazoles/1,3,5-Triazines via Defluorinative Annulations of N-CF3 Imidoyl Chlorides

Ring-fluorinated azaheterocycles have wide applications in agrochemicals, pharmaceuticals, and synthesis, which prompt continuous endeavors to expand such heterocyclic families. However, monofluorinated triazaheterocycles have hardly been explored. This work reported a novel and modular synthesis of monofluorinated 1,2,4-triazoles and 1,3,5-triazines, which utilizes N-CF3 imidoyl chlorides as unique polyfluoro synthons and their defluorinative annulations with hydrazines/imidazines. Further modifications of these fluorinated heterocycles highlight the potential of the method for accessing functional molecules.

N-Halosuccinimide enables cascade oxidative trifluorination and halogenative cyclization of tryptamine-derived isocyanides

Both the pyrroloindoline core and N-CF3 moiety hold significant importance in medicinal chemistry. However, to date, no instances of constructing N-CF3-containing pyrroloindolines have been reported. Herein, we present a robust and operationally simple approach to assembling such intriguing skeletons from tryptamine-derived isocyanides through a cascade sequence, which includes an oxidative trifluorination and a subsequent halogenative cyclization. Key to the success lies in the development of a facile conversion of isocyanides to N-CF3 moiety with commercially available reagents N-halosuccinimide and Et3N·HF. The protocol features mild reaction conditions, broad functional group tolerance, good to excellent yields, and high diastereoselectivities. In addition, we demonstrate that the halide substituent within the products serves as a versatile functional handle for accessing diverse C3-quaternary-substituted N-CF3-pyrroloindolines.

Recent Progress in Synthetic Applications of Hypervalent Iodine(III) Reagents

Hypervalent iodine(III) compounds have found wide application in modern organic chemistry as environmentally friendly reagents and catalysts. Hypervalent iodine reagents are commonly used in synthetically important halogenations, oxidations, aminations, heterocyclizations, and various oxidative functionalizations of organic substrates. Iodonium salts are important arylating reagents, while iodonium ylides and imides are excellent carbene and nitrene precursors. Various derivatives of benziodoxoles, such as azidobenziodoxoles, trifluoromethylbenziodoxoles, alkynylbenziodoxoles, and alkenylbenziodoxoles have found wide application as group transfer reagents in the presence of transition metal catalysts, under metal-free conditions, or using photocatalysts under photoirradiation conditions. Development of hypervalent iodine catalytic systems and discovery of highly enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important recent achievement in the field of hypervalent iodine chemistry. Chemical transformations promoted by hypervalent iodine in many cases are unique and cannot be performed by using any other common, non-iodine-based reagent. This review covers literature published mainly in the last 7-8 years, between 2016 and 2024.

Controllable Regioselective [3+2] Cyclizations of N-CF3 Imidoyl Chlorides and Ph3PNNC: Divergent Synthesis of N-CF3 Triazoles

Presented herein are two distinct regiodivergent [3+2] cyclization reactions between N-CF3 imidoyl chlorides and N-isocyaniminotriphenylphosphorane (NIITP) that include flexible modulation of the electronic properties of NIITP. The regioselectivity of reactions was different in the absence and presence of the Mo catalyst. The approach provides alternative efficient and scalable routes for N-CF3 triazole synthesis, demonstrating a broad substrate scope, excellent functional group tolerance, and practical advantages.

O-Trifluoromethylation of Carboxylic Acids via the Formation and Activation of Acyloxy(phenyl)trifluoromethyl-λ3-Iodanes

Here we report the challenging O-trifluoromethylation of carboxylic acids via the formation and activation of acyloxy(phenyl)trifluoromethyl-λ3-iodanes. The method provides an easy access to various potentially valuable and hitherto elusive trifluoromethyl carboxylic esters. A remarkably wide range of substrates with commonly encountered functional groups are compatible with this reaction, including aromatic and aliphatic carboxylic acids, as well as Food and Drug Administration (FDA) approved drugs and pharmaceutically relevant molecules. The reaction mechanism and the origins of the enhanced reactivity by zinc chloride (ZnCl2) were discussed from experimental evidence and density functional theory (DFT) calculation.

N-CF3 Imidoyl Chlorides: Scalable N-CF3 Nitrilium Precursors for the Construction of N-CF3 Compounds

A wide range of N-CF3 imidoyl chlorides were synthesized for the first time via the N-trifluoromethylation of nitriles in DCM by using AlCl3-activated PhICF3Cl as the CF3 source. The reactions of them with N-/O-/S-nucleophiles, as well as with 1,3-dipoles, were carried out to efficiently deliver N-CF3 amidines/imidates/thioimidates and N-CF3 azoles, demonstrating that they are a class of scalable NCF3-containing synthons in the synthesis of N-CF3 compounds.

Photocatalytic Generation of Trifluoromethyl Nitrene for Alkene Aziridination

N-Trifluoromethylated organics may be applied in drug design, agrochemical synthesis, and materials science, among other areas. Yet, despite recent advances in the synthesis of aliphatic, cyclic and heterocyclic N-trifluoromethyl compounds, no strategy based on trifluoromethyl nitrene has hitherto been explored. Here we describe the formation of triplet trifluoromethyl nitrene from azidotrifluoromethane, a stable and safe-to-use precursor, by visible light photocatalysis. The addition of CF3 N to alkenes via biradical intermediates afforded previously unknown aziridines substituted with trifluoromethyl group on the nitrogen atom. The obtained aziridines were converted into either N-trifluoromethylimidazolines, via formal [3+2] cycloaddition with nitriles, mediated by a Lewis acid, or into N-trifluoromethylaldimines, via ring opening and aryl group migration mediated by a strong Brønsted acid. Our findings open new opportunities for the development of novel classes of N-CF3 compounds with possible applications in the life sciences.

Formal (4+2) cycloaddition of azoalkenes with trifluoromethylimidoyl sulfoxonium ylides: synthesis of trifluoromethyl pyridazine derivatives

CF3-substituted imidoyl sulfoxonium ylides (TFISYs) are extraordinarily versatile and powerful synthons for use in cyclization chemistry that affords diverse CF3-substituted N-heterocycles. We first reacted TFISYs as a two-atom synthon with readily available azoalkenes and then subjected the products to metal-free formal (4+2) cycloaddition chemistry. This protocol features mild conditions and broad substrate scope, is simple to operate, and provides highly functionalized trifluoromethylpyridazines that are widely found in bioactive molecules.

Access to N-CF3 Formamides by Reduction of N-CF3 Carbamoyl Fluorides

The departure into unknown chemical space is essential for the discovery of new properties and function. We herein report the first synthetic access to N-trifluoromethylated formamides. The method involves the reduction of bench-stable NCF₃ carbamoyl fluorides and is characterized by operational simplicity and mildness, tolerating a broad range of functional groups as well as stereocenters. The newly made N-CF₃ formamide motif proved to be highly robust and compatible with diverse chemical transformations, underscoring its potential as building block in complex functional molecules.

Synthesis of N-CF3 Amidines/Imidates/Thioimidates via N-CF3 Nitrilium Ions

An efficient methodology for the synthesis of a wide range of N-CF₃ imidic acid derivatives is presented. In this reaction, N-CF₃ nitrilium ions were generated via N-trifluoromethylation of nitriles using PhICF₃Cl under catalysis with DMAP, followed by the capture of N-, O-, or S-centered nucleophiles to give diverse N-CF₃ amidines, imidates, and thioimidates. The method provides a platform for preparing N-CF₃ compounds with potential applications.