A general and practical Ni-catalyzed C-H perfluoroalkylation of (hetero)arenes

Advances in accessing rare oxidation states of nickel for catalytic innovation

Nickel catalysis has experienced a renaissance over the past two decades, driven by its ability to access diverse oxidation states (0 to +4) and unique reactivity. This review consolidates the advancements in nickel chemistry, providing an overview of ligands that stabilize specific nickel oxidation states. The stability, reactivity, and catalytic applications of Ni0 sources, including in situ generation from air- and moisture-stable NiII precursors, are discussed, along with the roles of NiI and NiIII intermediates in catalytic cycles. The progress in synthesizing and utilizing NiIV complexes highlights their emerging importance in catalysis. Advances in spectroscopic and theoretical tools have enhanced the understanding of nickel's complex catalytic behavior.

Recent advances on non-precious metal-catalysed fluorination, difluoromethylation, trifluoromethylation, and perfluoroalkylation of N-heteroarenes

This review highlights the recent advances, from 2015 to 2023, on the introduction of organo-fluorine derivatives at the N-heteroarene core. Notable features considering new technologies based on organofluorine compounds such as: (i) approaches based on non-precious metal catalysis (Fe, Co, Mn, Ni, etc.), (ii) the development of new strategies using non-precious metal-catalysts for the introduction of organo-fluorinine derivatives using N-heterocycles with one or more heteroatoms, (iii) newer reagents for fluorination, difluoromethylation, trifluoromethylation, or perfluoroalkylation of N-heteroarenes using different approaches, (iv) mechanistic studies on various catalytic transformations, as and when required, and (v) the synthetic applications of various bio-active organo-fluorine compounds, including post-synthetic drug derivatization, are discussed.

Activation of perfluoroalkyl iodides by anions: extending the scope of halogen bond activation to C(sp3)-H amidation, C(sp2)-H iodination, and perfluoroalkylation reactions

A simple, efficient, and convenient activation of perfluoroalkyl iodides by tBuONa or KOH, without expensive photo- or transition metal catalysts, allows the promotion of versatile α-sp³ C-H amidation reactions of alkyl ethers and benzylic hydrocarbons, C-H iodination of heteroaryl compounds, and perfluoroalkylations of electron-rich π bonds. Mechanistic studies show that these novel protocols are based on the halogen bond interaction between perfluoroalkyl iodides and tBuONa or KOH, which promote homolysis of perfluoroalkyl iodides under mild conditions.

Ligand-free nickel catalyzed perfluoroalkylation of arenes and heteroarenes

We describe a "ligand-free" Ni-catalyzed perfluoroalkylation of heteroarenes to produce a diverse array of trfiluoromethyl, pentafluoroethyl and heptafluoropropyl adducts. Catalysis proceeds at room temperature via a radical pathway. The catalytic protocol is distinguished by its simplicity, and its wide scope demonstrates the potential in the late-stage functionalization of drug analogues and peptides.

Recent Developments and Aspects of Industrial Fluoroalkylation

Fluoroalkylations have received increasing attention in the academic and industrial environment due to the particular properties of the active ingredients that are strongly influenced by fluoroalkyl substituents. The inherent difficulties of introducing a fluoroalkyl substituent into advanced intermediates has triggered the development of an enormous number of specialized reagents, which, however, are often not suitable for large scale applications. In contrast to this reagent based fluoroalkylation approach, the direct activation of industrially readily available fluoroalkyl halides could be more suitable for a large-scale process. In this way the dithionite initiated fluoroalkylation as well as newly developed catalytically activated fluoroalkylation protocols were considered for industrial large-scale applications.

3,3-Difluoroallyl ammonium salts: highly versatile, stable and selective gem-difluoroallylation reagents

The selective synthesis of fluorinated organic molecules continues to be of major importance for the development of bioactive compounds (agrochemicals and pharmaceuticals) as well as unique materials. Among the established synthetic toolbox for incorporation of fluorine-containing units, efficient and general reagents for introducing -CF2- groups have been largely neglected. Here, we present the synthesis of 3,3-difluoropropen-1-yl ammonium salts (DFPAs) as stable, and scalable gem-difluoromethylation reagents, which allow for the direct reaction with a wide range of fascinating nucleophiles. DFPAs smoothly react with N-, O-, S-, Se-, and C-nucleophiles under mild conditions without necessity of metal catalysts with exclusive regioselectivity. In this way, the presented reagents also permit the straightforward preparation of many analogues of existing pharmaceuticals.

Palladium-Catalyzed C2-Regioselective Perfluoroalkylation of the Free (NH)-Heteroarenes

A highly regioselective and atom-efficient strategy for the construction of fused free (NH) heteroarenes through a palladium-catalyzed perfluoroalkyl insertion reaction has been accomplished. This protocol employed multiple iodofluoroalkanes as practical and available perfluoroalkyl sources to provide an operationally simple and versatile route for the synthesis of perfluoroalkylated indoles. Moreover, indoles without the assistance of guide groups were utilized as substrates, achieving C(sp²)-H site-selective functionalization of indoles in yields up to 95%. Furthermore, this protocol was also used for late-stage C2 perfluoroalkylation of bioactive compounds such as auxin, tryptophan, and melatonin analogues.

Catalyst-free, visible-light-induced direct radical cross-coupling perfluoroalkylation of the imidazo[1,2-a]pyridines with perfluoroalkyl iodides

A mild and eco-friendly visible-light-induced direct radical cross-coupling perfluoroalkylation of the imidazo[1,2-a]pyridines with perfluoroalkyl iodides was established.

Selective nickel-catalyzed fluoroalkylations of olefins

Mild and selective nickel-catalyzed trifluoromethylation and perfluoroalkylation reactions of alkenes were developed to provide fluorinated olefins, including natural products, pharmaceuticals, and variety of synthetic building blocks in good to excellent yields (38 examples). Control experiments, kinetic measurements and in situ EPR studies reveal the importance of radical species and the formation of 1,2-adducts as intermediates.

Ruthenium-Catalyzed Site-Selective Trifluoromethylations and (Per)Fluoroalkylations of Anilines and Indoles

Introducing (per)fluoroalkyl groups into arenes continues to be an interesting, but challenging area in organofluorine chemistry. We herein report an ortho-selective C-H perfluoroalkylation including trifluoromethylations of anilines and indoles without the need of protecting groups using Rf I and Rf Br as commercially available reagents. The availability and price of the starting materials and the inherent selectivity make this novel methodology attractive for the synthesis of diverse (per)fluoroalkylated building blocks, for example, for bioactive compounds and materials.

Towards a practical perfluoroalkylation of (hetero)arenes with perfluoroalkyl bromides using cobalt nanocatalysts

This paper report a convenient methodology for perfluoroalkylation including trifluoromethylation of (hetero)arenes with perfluoroalkyl bromides using a specific cobalt-based nanocatalyst.

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 solvents and R_FI is presented.