Silver-Catalyzed Decarboxylative Alkylfluorination of Alkenes

Silver-Catalyzed Carbofluorination of Olefins and α-Fluoroolefins with Carbamoyl Radicals

The reactivity of carbamoyl radicals, generated in situ from sodium oxamate salts, has been investigated in the context of radical carbofluorination reactions of olefins and α-fluoroolefins, respectively. Both transformations are catalyzed by silver salts and required the presence of potassium persulfate (K2S2O8) and SelectfluorTM as a radicophilic fluorine source. The reported methods provide a direct access to β-fluoroamides and β,β-difluoroamides.

Silver-Catalyzed Decarboxylative Remote Fluorination via a Zwitterion-Promoted 1,4-Heteroaryl Migration

A silver-catalyzed decarboxylative remote fluorination via a zwitterion-promoted 1,4-heteroaryl migration has been developed. A variety of heteroaryl-tethered benzyl fluorides have been readily synthesized with good regioselectivity under mild conditions. The zwitterion of the substrate is suggested to accelerate the 1,4-heteroaryl migration, which determines the regioselectivity of this transformation.

Chemo- and Diastereoselective Acylfluorination of Nonactivated Olefins to Access Benzo[b]azepines

Here, we describe a transition-metal-free condition that realized the intramolecular acylfluorination of unactivated olefins. It was designed to access seven-membered-ring-containing benzo[b]annulenones from readily prepared 2-allylamino benzoic acids. The formation of a broad scope of electronically and sterically varied benzo[b]annulenones was demonstrated (>30 examples, up to 88% yield and >20:1 dr ratio). Mechanistic studies indicated that the in situ formed XatlFluor-E-activated anhydride was the active species and induced an electrophilic 7-endo-trig cyclization, followed by fluoride capture of the cation.

A Straightforward Approach to Fluorinated Pyrimido[1,2-b]indazole Derivatives via Metal/Additive-Free Annulation with Enaminones, 3-Aminoindazoles, and Selectfluor

A novel and efficient three-component reaction with two C-N bonds and one C-F bond formation has been reported, which provides a straightforward route to a variety of fluorinated pyrimido[1,2-b]indazole derivatives. This transformation has the advantage of excellent functional group compatibility, including aliphatic and aromatic substituents enaminones. Moreover, metal and additives are not necessary for this reaction, which is of great significance for the synthesis and application of fluorinated heterocycles.

anti-Markovnikov Iodofluorination of Alkenes

The fluorination of alkenes with electrophilic N-F type reagents usually occurs through a Markovnikov-type addition, and the anti-Markovnikov-type addition may require the use of a transition metal catalyst or an expensive catalyst. Herein we describe a convenient anti-Markovnikov iodofluorination of alkenes with Selectfluor/ nBu4NI. A wide substrate scope and good functional group tolerance were observed. The process allows for the construction of various C-F bonds, especially tertiary C-F bonds. The remarkable features make this protocol attractive, including convenient operations, simple reaction conditions, and the installation of an iodine atom which provides possibilities for further transformations.

Direct decarboxylative Giese reactions

The quest to find milder and more sustainable methods to generate highly reactive, carbon-centred intermediates has led to a resurgence of interest in radical chemistry. In particular, carboxylic acids are seen as attractive radical precursors due their availability, low cost, diversity, and sustainability. Moreover, the corresponding nucleophilic carbon-radical can be easily accessed through a favourable radical decarboxylation process, extruding CO₂ as a traceless by-product. This review summarizes the recent progress on using carboxylic acids directly as convenient radical precursors for the formation of carbon-carbon bonds via the 1,4-radical conjugate addition (Giese) reaction.

Photoredox-Catalyzed Oxidative Radical-Polar Crossover Enables the Alkylfluorination of Olefins

The three-component alkylfluorination of olefins via an oxidative radical-polar crossover under visible light-induced photocatalysis is disclosed. A key feature of this reaction is the incorporation of two synthetically meaningful components involving a three-dimensional alkyl group and a fluorine atom using easily preparable N-hydroxyphthalimide esters as the alkyl donors and a low-cost hydrogen fluoride as the fluorine source. Furthermore, a one-step procedure using commercially available carboxylic acids demonstrated the versatility of this new method.

Visible-Light-Driven Photoredox-Catalyzed Three-Component Radical Cyanoalkylfluorination of Alkenes with Oxime Esters and a Fluoride Ion

A metal-free, photoredox-catalyzed three-component cyanoalkylfluorination of alkenes under mild and redox-neutral conditions is reported. This protocol features use of readily available alkenes, oxime esters, and cost-effective nucleophilic fluoride reagents, giving diverse cyanoalkylfluorinated products with generally good yields. Excellent functional group tolerance and mild reaction conditions also render this protocol suitable for cyanoalkylfluorination of pharmaceutically relevant molecule-derived alkene.

Wonderful fusion of organofluorine chemistry and decarboxylation strategy

Decarboxylation strategy has been emerging as a powerful tool for the synthesis of fluorine-containing organic compounds that play important roles in various fields such as pharmaceuticals, agrochemicals, and materials science. Considerable progress in decarboxylation has been made over the past decade towards the construction of diverse valuable fluorinated fine chemicals for which the fluorinated part can be brought in two ways. The first way is described as the reaction of non-fluorinated carboxylic acids (and their derivatives) with fluorinating reagents, as well as fluorine-containing building blocks. The second way is dedicated to the exploration and the use of fluorine-containing carboxylic acids (and their derivatives) in decarboxylative transformations. This review aims to provide a comprehensive summary of the development and applications of decarboxylative radical, nucleophilic and cross-coupling strategies in organofluorine chemistry.

Visible-Light-Induced Meerwein Fluoroarylation of Styrenes

An unprecedented approach for assembling a broad range of 1,2-diarylethane derivatives with fluorine-containing fully substituted carbon centers was developed. The protocol features straightforward operation, proceeds under metal-free condition, and accommodates a large variety of synthetically useful functionalities. The critical aspect to the success of this novel transformation lies in using aryldiazonium salts as both aryl radical progenitor and also as single electron acceptor which elegantly enables a radical-polar crossover manifold.

Copper-catalyzed one-pot amine-alkylation of quinones with amines and alkanes

A copper-catalyzed one-pot amine-alkylation of quinones with amines and alkanes in the presence of di-tert-butyl peroxide (DTBP) was developed via a radical reaction process. Various alkanes and aromatic or aliphatic amines with diverse structures and electronic properties are suitable substrates, and the chirality of amines can be maintained for the transformation. This method has high step and atom economy for straightforward access to aminated and alkylated quinones from readily available starting materials.