Electrophilic trifluoromethylation by use of hypervalent iodine reagents

Palladium-Catalyzed Monofluoromethylation of Arylboronic Esters with Fluoromethyl Iodide

The first palladium-catalyzed direct monofluoromethylation of arylboronic esters to produce monofluoromethyl arenes is reported. The reaction is typically carried out at room temperature within 4 h and has a good functional group tolerance. The monofluoromethylating agent, CH2FI, was readily prepared via a halogen-exchange process.

Trifluoromethyl-substituted sulfonium ylide: Rh-catalyzed carbenoid addition to trifluoromethylthioether

A highly efficient Rh-catalyzed carbenoid addition to trifluoromethylthioether for the formation of trifluoromethyl-substituted sulfonium ylide is described. The trifluoromethyl-substituted sulfonium ylide can act as an electrophilic trifluoromethylation reagent, as demonstrated by trifluoromethylation of β-ketoesters and aryl iodides.

In Situ generation of difluoromethyl diazomethane for [3+2] cycloadditions with alkynes

A novel approach to agrochemically important difluoromethyl-substituted pyrazoles has been developed based on the elusive reagent CF2 HCHN2 , which was synthesized (generated in situ) for the first time and employed in [3+2] cycloaddition reactions with alkynes. The reaction is extremely practical as it is a one-pot process, does not require a catalyst or the isolation of the potentially toxic and explosive gaseous intermediate, and proceeds in a common solvent, namely chloroform, in air. The reaction is also scalable and allows for the preparation of the target pyrazoles on gram scale.

Catalytic trifluoromethylation of aryl- and vinylboronic acids by 2-cyclopropyl-1-(trifluoromethyl)benzo[b]thiophenium triflate

Catalytic trifluoromethylation of aryl- and vinylboronic acids by 2-cyclopropyl-1-(trifluoromethyl)benzo[b]thiophenium triflate is described. In the presence of a catalytic amount of CuOAc and 2,4,6-collidine in ethyl acetate, the reaction proceeded in good to high yields for various substrates under mild reaction conditions at room temperature.

Dividing a complex reaction involving a hypervalent iodine reagent into three limiting mechanisms by ab initio molecular dynamics

The electrophilic N-trifluoromethylation of MeCN with a hypervalent iodine reagent to form a nitrilium ion, that is rapidly trapped by an azole nucleophile, is thought to occur via reductive elimination (RE). A recent study showed that, depending on the solvent representation, the S(N)2 is favoured to a different extent over the RE. However, there is a discriminative solvent effect present, which calls for a statistical mechanics approach to fully account for the entropic contributions. In this study, we perform metadynamic simulations for two trifluoromethylation reactions (with N- and S-nucleophiles), showing that the RE mechanism is always favoured in MeCN solution. These computations also indicate that a radical mechanism (single electron transfer) may play an important role. The computational protocol based on accelerated molecular dynamics for the exploration of the free energy surface is transferable and will be applied to similar reactions to investigate other electrophiles on the reagent. Based on the activation parameters determined, this approach also gives insight into the mechanistic details of the trifluoromethylation and shows that these commonly known mechanisms mark the limits within which the reaction proceeds.

Perfluoroalkylation reactions of (hetero)arenes

Methods for the perfluoroalkylation of (hetero)arenes can be classified as thermal and photochemical, which in turn can be conducted in the presence or absence of metals.

Electrophilic trifluoromethylthiolation of thiols with trifluoromethanesulfenamide

Efficient and highly selective, metal-free, acid promoted synthesis of trifluoromethyl disulfides from thiols and PhNHSCF₃ is described.

Preparation of iodonium ylides: probing the fluorination of 1,3-dicarbonyl compounds with a fluoroiodane

The isolated iodonium ylide has been reacted successfully with TREAT-HF, hydrochloric acid, acetic acid and p-toluenesulfonic acid to form the 2-fluoro-, 2-chloro-, 2-acetyl- and 2-tosyl-1,3-ketoesters respectively.

Copper-catalyzed trifluoromethylation of organic zinc reagents with an electrophilic trifluoromethylating reagent

Trifluoromethylation of aryl and alkyl zinc reagents under mild conditions was described.

Silver-catalyzed Meerwein arylation: intermolecular and intramolecular fluoroarylation of styrenes

The first example of silver-catalyzed intermolecular and intramolecular Meerwein fluoroarylation of styrenes with aryl diazonium salts was reported.

Copper-catalyzed trifluoromethylation of alkenes: synthesis of trifluoromethylated benzoxazines

A ligand and base free copper catalyzed method has been developed for the construction of trifluoromethylated benzoxazines by using Umemoto's reagent.

Benzylic C–H trifluoromethylation of phenol derivatives

Phenol derivatives were trifluoromethylated using copper/Togni reagent. Reaction in DMF selectively gave benzylic trifluoromethylation products, whereas aromatic trifluoromethylation products were obtained in t-BuOH.

Efficient direct 2,2,2-trifluoroethylation of indoles via C–H functionalization

Metal free direct trifluoroethylation of unprotected indoles at position 3 via C–H functionalization is presented: straightforward synthesis and DFT studies.

Introducing a new radical trifluoromethylation reagent

Radical trifluoromethylations of aromatic molecules have been achieved by using a persistent perfluoroalkyl radical as a precursor of the CF₃ radical. The process works efficiently in terms of chemical yields to produce mixtures of regioisomeric trifluoromethylated compounds.

Regioselective access to CF3S-substituted dihydrofurans from homopropargylic alcohols with trifluoromethanesulfenamide

A facile access to 4-((trifluoromethyl)thio)-2,3-dihydrofurans from unprotected homopropargylic alcohols in high regioselectivity is reported.

Direct trifluoromethylation of imidazoheterocycles in a recyclable medium at room temperature

Regioselective C–H trifluoromethylation of imidazoheterocycles with Langlois' reagent in a recyclable mixed medium of 1-butyl-3-methylimidazoliumtetrafluoroborate ([Bmim]BF₄) and water at room temperature has been developed.

Three-component synthesis of fluorinated pyrazoles from fluoroalkylamines, NaNO2 and electron-deficient alkynes

Three-component synthesis of fluorinated pyrazoles.

Facile synthesis of 1-trifluoromethylalkenes via the decarboxylation of α-trifluoromethyl-β-lactones

DCC-mediated cyclodehydration of α-trifluoromethyl-β-hydroxy acids provides α-trifluoromethylated β-lactone intermediates, without loss of stereoselectivity. These lactones undergo facile decarboxylation providing a simple route to obtain both alkyl and aryl 1-trifluoromethyl alkenes in excellent yields and stereoselectivity.

Copper(i)-photocatalyzed trifluoromethylation of alkenes

Using the photoreducible Cu^II precatalyst 2, trifluoromethylation of terminal alkenes can be conducted at low copper loading on exposing the reaction mixture to sunlight/ambient light.

Copper-catalysed ring-opening trifluoromethylation of cyclopropanols

A copper catalyzed ring-opening trifluoromethylation of cyclopropanols under mild reaction conditions was developed. A wide variety of synthetically useful β-trifluoromethyl ketones were obtained.

CF3-Substituted semisquarate: a pluripotent building block for the divergent synthesis of trifluoromethylated functional molecules

The first synthesis of a CF₃-substituted semisquarate was accomplished via nucleophilic trifluoromethylation using CF₃SiMe₃ and subsequent rhenium-catalyzed allylic alcohol rearrangement.

Preparation, structure, and versatile reactivity of pseudocyclic benziodoxole triflate, new hypervalent iodine reagent

New, highly electrophilic hypervalent iodine reagent, triflate derivative of benziodoxole, was prepared and structurally characterized.