Good partnership between sulfur and fluorine: sulfur-based fluorination and fluoroalkylation reagents for organic synthesis

Iodine(III)-Mediated Oxy-fluorination of Alkenyl Oximes: An Easy Path to Monofluoromethyl-Substituted Isoxazolines

A highly regioselective intramolecular oxy-fluorination of alkenyl oximes was achieved. This new transformation represents an efficient method for the preparation of monofluoromethyl-substituted isoxazolines. The synthetic application of the oxy-fluorination product was demonstrated by a one-step synthesis of monofluoromethyl-substituted β-hydroxyl ketone derivatives.

Visible light-induced selective hydrobromodifluoromethylation of alkenes with dibromodifluoromethane

A visible light-induced selective hydrobromodifluoromethylation of alkenes using CF2Br2 was developed. This transformation proceeded smoothly in the presence of catalytic eosin Y at room temperature to give various hydrobromodifluoromethylated compounds with broad functional group tolerance.

Anti-Diastereoselective Synthesis of CF3-Containing Spirooxazolines and Spirooxazines via Regiospecific Trifluoromethylative Spirocyclization by Photoredox Catalysis

A novel synthesis of CF3-containing spirooxazolines and spirooxazines has been developed. Regiospecific trifluoromethylative spirocyclization (CF3-spirocyclization) of cyclic alkenes bearing an amide pendant mediated by photoredox catalysis is a useful strategy for construction of a C(sp(3))-CF3 bond and an spirooxazoline or spirooxazine ring onto C═C bonds via a single step. The key intermediate is α-CF3-substituted carbocationic species smoothly generated from single-electron-transfer (SET) photoredox processes, which results in diastereoselective spirocyclization. This is the first example of synthesis of CF3-containing spirooxazolines and spirooxazines in anti-fashion with respect to the CF3 group and the oxygen atom of the spirocycles.

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.

Efficient Synthesis of β-CF3/SCF3-Substituted Carbonyls via Copper-Catalyzed Electrophilic Ring-Opening Cross-Coupling of Cyclopropanols

The first copper-catalyzed ring-opening electrophilic trifluoromethylation and trifluoromethylthiolation of cyclopropanols to form Csp3-CF3 and Csp3-SCF3 bonds have been realized. These transformations are efficient for the synthesis of β-CF3- and β-SCF3-substituted carbonyl compounds that are otherwise challenging to access. The reaction conditions are mild and tolerate a wide range of functional groups. Application to a concise synthesis of LY2409021, a glucagon receptor antagonist that is used in clinical trials for type 2 diabetes mellitus, is reported as well.

Nickel-catalyzed monofluoromethylation of aryl boronic acids

Aryl boronic acids can be monofluoromethylated under nickel catalysis. The utility of this method is demonstrated by the monofluoromethylation of a borylated and acyl-protected derivative of the statin drug ezetimibe. Mechanistic investigations indicate that a fluoromethyl radical is involved in the Ni(I)/Ni(III) catalytic cycle.

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.

Radical-based route to 2-(trifluoromethyl)-1,3,4-oxadiazoles and trifluoromethyl-substituted polycyclic 1,2,4-triazoles and dihydrofurans

O-Ethyl S-[5-(trifluoromethyl)-1,3,4-oxadiazol-2-yl]methyl xanthate was readily prepared on a large scale and shown to undergo very efficient intermolecular radical additions to unactivated alkenes. The products were further elaborated by exploiting both radical and ionic processes to provide a variety of trifluoromethyl-substituted derivatives, including medicinally relevant triazoles. In particular, the application of a radical allylation on the initial adducts leads to structures that are able to undergo intramolecular [4 + 2] cycloaddition reactions.

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.

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.

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.

Difluoromethyl 2-pyridyl sulfone: a versatile carbonyl gem-difluoroolefination reagent

The gem-difluoroolefination of carbonyl compounds with difluoromethyl 2-pyridyl sulfone (2-PySO₂CF₂H) has been summarized in this tutorial account.

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

Three-component synthesis of fluorinated pyrazoles.

Organocatalytic direct difluoromethylation of aldehydes and ketones with TMSCF2H

Organocatalytic direct difluoromethylation of aldehydes and ketones with TMSCF₂H.

Solvent-controlled nucleophilic trifluoromethylthiolation of Morita–Baylis–Hillman carbonates: dual roles of DABCO in activating the Zard's trifluoromethylthiolation reagent and the MBH carbonates

A novel amine-catalyzed nucleophilic trifluoromethylthiolation between Morita–Baylis–Hillman carbonates and O-octadecyl-S-trifluorothiolcarbonate has been developed.

A direct catalytic ring expansion approach to o-fluoronaphthols and o/p-fluorophenols from indanones and 2-cyclopentenones

A catalytic ring expansion of indanones to o-fluoronaphthols is described by taking advantage of the multi-reactivities of TMSCF₂Br.