Direct Trifluoromethylation of the CH Bond

Transition-metal-free direct perfluoroalkylation of quinoline amides at C5 position through radical cross-coupling under mild conditions

A simple low-energy and efficient method is established for the synthesis of C5-selective perfluoroalkylation quinolines in the absence of any transition metal catalysts.

Efficient trifluoromethylation of C(sp2)–H functionalized α-oxoketene dithioacetals: a route to the regioselective synthesis of functionalized trifluoromethylated pyrazoles

An operationally simple approach for regioselective construction of substituted trifluoromethylated pyrazoles via ligand free nucleophilic trifluoromethylation of iodo-substituted α-oxoketene dithioacetals.

Phosphovanadomolybdic acid catalyzed direct C–H trifluoromethylation of (hetero)arenes using NaSO2CF3 as the CF3 source and O2 as the terminal oxidant

In the presence of phosphovanadomolybdic acids, a direct C–H trifluoromethylation of (hetero)arenes efficiently proceeded by utilizing NaSO₂CF₃ as the CF₃ source and O₂ as the terminal oxidant.

Copper-catalyzed trifluoromethylazidation and rearrangement of aniline-linked 1,7-enynes: access to CF3-substituted azaspirocyclic dihydroquinolin-2-ones and furoindolines

A set of reactions involving copper-catalyzed trifluoromethylazidation and then rearrangement of aniline-linked 1,7-enynes was developed, and provided facile access to azaspirocyclic dihydroquinolin-2-ones, furoindolines and functionalized aziridines.

Biocatalytic trifluoromethylation of unprotected phenols

Organofluorine compounds have become important building blocks for a broad range of advanced materials, polymers, agrochemicals, and increasingly for pharmaceuticals. Despite tremendous progress within the area of fluorination chemistry, methods for the direct introduction of fluoroalkyl-groups into organic molecules without prefunctionalization are still highly desired. Here we present a concept for the introduction of the trifluoromethyl group into unprotected phenols by employing a biocatalyst (laccase), tBuOOH, and either the Langlois' reagent or Baran's zinc sulfinate. The method relies on the recombination of two radical species, namely, the phenol radical cation generated directly by the laccase and the CF3-radical. Various functional groups such as ketone, ester, aldehyde, ether and nitrile are tolerated. This laccase-catalysed trifluoromethylation proceeds under mild conditions and allows accessing trifluoromethyl-substituted phenols that were not available by classical methods.

Visible-Light-Induced Trifluoromethylation of Isonitrile-Substituted Methylenecyclopropanes: Facile Access to 6-(Trifluoromethyl)-7,8-Dihydrobenzo[k]phenanthridine Derivatives

A new visible-light-induced trifluoromethylation of isonitrile-substituted methylenecyclopropanes is developed. A range of substituted 6-(trifluoromethyl)-7,8-dihydrobenzo[k]phenanthridine derivatives are readily furnished by this newly developed tandem reaction with moderate to good yields. This reaction allows the direct formation of two six-membered rings and three new C-C bonds, including the C-CF3 bond, under visible light irradiation.

Methyl fluorosulfonyldifluoroacetate (MFSDA): An Underutilised Reagent for Trifluoromethylation

The introduction of fluorine groups to pharmaceutical compounds can have a dramatic effect on the lipophilicity and metabolic stability of the molecule in vivo. Around 20 % of drugs contain at least one fluorine atom. The trifluoromethyl group is known to have beneficial effects and can dramatically affect the biological activity when substituted for a methyl group, for example. In any case, the direct and late-stage introduction of a trifluoromethyl group is a powerful transformation in the tool box of the medicinal chemist. The use of methyl fluorosulfonyldifluoroacetate (MFSDA) as a relatively inexpensive reagent for trifluoromethylation was first reported in 1989; however, in our opinion it has been somewhat underutilised. Herein, a comprehensive review of trifluoromethylation using MFSDA is reported, which we hope will further expose readers to this useful reagent.

4-Position-Selective C-H Perfluoroalkylation and Perfluoroarylation of Six-Membered Heteroaromatic Compounds

The first 4-position-selective C-H perfluoroalkylation and perfluoroarylation of six-membered heteroaromatic compounds were achieved using nucleophilic perfluoroalkylation and perfluoroarylation reagents. The regioselectivity was controlled by electrophilically activating the heteroaromatic rings, while sterically hindering the 2-position, with a sterically bulky borane Lewis acid. The reaction proceeded in good yield, even in gram scale, and by a sequential reaction without isolating the intermediates. This reaction could be applied to late-stage trifluoromethylation of a bioactive compound.

Synthesis of 3-fluoroalkenyl-3-trifluoromethyl-2-oxindoles by the reaction of indoline-2,3-diones with difluoromethylene phosphabetaine

An unprecedent reaction of indoline-2,3-diones and (triphenylphosphonio)difluoroacetate (PDFA) afforded novel 3-fluoroalkenyl-3-trifluoromethyl-2-oxindoles in moderate to excellent yields. These products could be transformed into other trifluoromethylated oxindole derivatives.

Oxydifluoromethylation of Alkenes by Photoredox Catalysis: Simple Synthesis of CF2H-Containing Alcohols

We have developed a novel and simple protocol for the direct incorporation of a difluoromethyl (CF2 H) group into alkenes by visible-light-driven photoredox catalysis. The use of fac-[Ir(ppy)3] (ppy=2-pyridylphenyl) photocatalyst and shelf-stable Hu's reagent, N-tosyl-S-difluoromethyl-S-phenylsulfoximine, as a CF2 H source is the key to success. The well-designed photoredox system achieves synthesis of not only β-CF2 H-substituted alcohols but also ethers and an ester from alkenes through solvolytic processes. The present method allows a single-step and regioselective formation of C(sp(3))-CF2 H and C(sp(3))-O bonds from C=C moiety in alkenes, such as hydroxydifluoromethylation, regardless of terminal or internal alkenes. Moreover, this methodology tolerates a variety of functional groups.

Palladium catalyzed C–H bond acetoxylation: isoxazolinyl as a directing group

Pd(OAc)₂-catalyzed acetoxylations of 3-aryl or 3-alkyl groups mounted on a 2-isoxazoline ring were studied. Substituent effect on reactivity and regioselectivity was examined. The acetoxylation was applied to the synthesis of useful intermediates.

Recent advances in photoinduced trifluoromethylation and difluoroalkylation

Recent advances in photoinduced trifluoromethylation and difluoroalkylation under photocatalysis are summarized. Most of the photoredox reactions proceed efficiently under mild conditions with simple operation. Various fluorinated reagents are developed and applied in different transformations.

Design for carbon–carbon bond forming reactions under ambient conditions

The carbon–carbon (C–C) bond forms the ‘backbone’ of nearly every organic molecule, and lies at the heart of the chemical sciences! Let us explore designing of carbon–carbon frameworks at ambient conditions.

New entries toward the synthesis of OCF3-containing molecules

The OCF₃ group is of high interest in the quest for new drugs and agrochemicals, thanks to its atypical features. This Highlight article depicted the recent and impressive advances toward the synthesis of OCF₃-containing molecules.

A general route to fluorinated 3,3-disubstituted 2-oxindoles via a photoinduced radical cyclization of N-arylacrylamides under catalyst-free conditions

A catalyst-free radical cyclization of N-arylacrylamides with fluorinated alkyl iodides or the Togni reagent enabled by photoenergy is reported, leading to fluorinated 2-oxindoles in good yields. The broad reaction scope is demonstrated with good functional group tolerance.

Direct vicinal difunctionalization of alkynes through trifluoromethylation and aminosulfonylation via insertion of sulfur dioxide under catalyst-free conditions

Direct vicinal difunctionalization of alkynes through a catalyst-free four-component reaction of Togni's reagent, alkynes, sulfur dioxide, and hydrazines at room temperature is developed, which generates (E)-3,3,3-trifluoroprop-1-ene-1-sulfonohydrazides in good yields.

Synthesis of trifluoromethylated 3,4-dihydroquinolin-2(1H)-ones via a photo-induced radical cyclization of benzene-tethered 1,7-enynes with Togni reagent

A photoinduced radical cyclization of benzene-tethered 1,7-enynes with Togni reagent in the presence of sodium iodide is developed. This transformation works well without any metals or photo-redox catalysts at room temperature.

Electrophilic trifluoromethylation of carbonyl compounds and their nitrogen derivatives under copper catalysis

Recent advances in copper-catalyzed electrophilic trifluoromethylation of carbonyl compounds and their nitrogen derivatives are highlighted with particular focus on C–CF₃ bond forming reactions.

Carbon-carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

This short review highlights the copper-mediated fluoroalkylation using perfluoroalkylated carboxylic acid derivatives. Carbon–carbon bond cleavage of perfluoroalkylated carboxylic acid derivatives takes place in fluoroalkylation reactions at high temperature (150–200 °C) or under basic conditions to generate fluoroalkyl anion sources for the formation of fluoroalkylcopper species. The fluoroalkylation reactions, which proceed through decarboxylation or tetrahedral intermediates, are useful protocols for the synthesis of fluoroalkylated aromatics.

Direct Catalytic Asymmetric Mannich-Type Reaction of α- and β-Fluorinated Amides

The last two decades have witnessed the emergence of direct enolization protocols providing atom-economical and operationally simple methods to use enolates for stereoselective C-C bond-forming reactions, eliminating the inherent drawback of the preformation of enolates using stoichiometric amounts of reagents. In its infancy, direct enolization relied heavily on the intrinsic acidity of the latent enolates, and the reaction scope was limited to readily enolizable ketones and aldehydes. Recent advances in this field enabled the exploitation of carboxylic acid derivatives for direct enolization, offering expeditious access to synthetically versatile chiral building blocks. Despite the growing demand for enantioenriched fluorine-containing small molecules, α- and β-fluorinated carbonyl compounds have been neglected in direct enolization chemistry because of the competing and dominating defluorination pathway. Herein we present a comprehensive study on direct and highly stereoselective Mannich-type reactions of α- and β-fluorine-functionalized 7-azaindoline amides that rely on a soft Lewis acid/hard Brønsted base cooperative catalytic system to guarantee an efficient enolization while suppressing undesired defluorination. This protocol contributes to provide a series of fluorinated analogs of enantioenriched β-amino acids for medicinal chemistry.

Copper-Mediated Formation of Aryl, Heteroaryl, Vinyl and Alkynyl Difluoromethylphosphonates: A General Approach to Fluorinated Phosphate Mimics

A general and efficient access to aryl, heteroaryl, vinyl and alkynyl difluoromethylphosphonates is described. The developed methodology using TMSCF2PO(OEt)2, iodonium salts and a copper salt provided a straightforward manifold to reach these highly relevant products. The reaction proved to be highly functional group tolerant and proceeded under mild conditions, giving the corresponding products in good to excellent yields. This method represents the first general synthetic route to this important class of fluorinated scaffolds, which are well-recognized as in vivo stable phosphate surrogates.