General and selective syn-carboxylation-trifluoromethylation of terminal alkynes: application to the late-stage modification of dehydrocholic acid

A formal vinylic substitution reaction for the synthesis of α,β-unsaturated enol esters and their anticancer potential

Arylsulfonyl group-bearing α,β-unsaturated enol esters were readily assembled via the Cs2CO3-mediated union of 2-bromoallyl sulfones and cinnamic acids. The overall transformation is equivalent to an sp2 carbon-oxygen coupling reaction, and therefore constitutes a formal vinylic substitution. Several of the products display promising levels of antiproliferative activities higher than that of the anticancer drug carboplatin. Thiophenol reacted with 2-bromoallyl sulfones under identical conditions to afford α-thiophenyl-α'-tosyl acetone via an apparent aerial oxidation.

Dual Oxidation of Epoxides with a High-Valent Cu(III)-CF3 Compound and DMSO to Access 1,2-Diketones

This study reports sequential dehydrogenation and transfer oxygenation of 1,2-diarylepoxides by high-valent phenCu(III)(CF3)3 and DMSO to produce 1,2-diketones. The Cu(III)-CF3 compound serves as a CF3 radical source to abstract the hydrogen atom of the epoxide ring. The resulting ether α-carbon radical undergoes ring-opening rearrangement to give a ketone α-carbon radical intermediate, which is oxygenated by DMSO with the release of Me2S. The combination of a Cu(III)-CF3 compound and DMSO may be exploited to develop other novel oxidation reactions.

Cross-Coupling Reactions Enabled by Well-Defined Ag(III) Compounds: Main Focus on Aromatic Fluorination and Trifluoromethylation

AgIII compounds are considered strong oxidizers of difficult handling. Accordingly, the involvement of Ag catalysts in cross-coupling via 2e- redox sequences is frequently discarded. Nevertheless, organosilver(III) compounds have been authenticated using tetradentate macrocycles or perfluorinated groups as supporting ligands, and since 2014, first examples of cross-coupling enabled by AgI /AgIII redox cycles saw light. This review collects the most relevant contributions to this field, with main focus on aromatic fluorination/perfluoroalkylation and the identification of AgIII key intermediates. Pertinent comparison between the activity of AgIII RF compounds in aryl-F and aryl-CF3 couplings vs. the one shown by its CuIII RF and AuIII RF congeners is herein disclosed, thus providing a more profound picture on the scope of these transformations and the pathways commonly associated to C-RF bond formations enabled by coinage metals.

High-valent Cu(III)-CF3 compound-mediated esterification reaction

Cu(III)-CF₃ compounds are reported herein as novel coupling reagents to mediate ester synthesis from carboxyl acids and alcohols/phenols. Carboxylic acids are transformed to trifluoromethyl ester and acyl fluoride activated species that interact with each other. The broad substrate scope and late-stage application of this method are demonstrated. This study opens up new opportunities to develop interesting reactions using Cu(III)-CF₃ compounds without transferring a CF₃ group to the products.

A diastereoselective synthesis of cyclopentanones via photocatalytic reductive alkyltrifluoromethylation of ynones

A photocatalytic reductive alkyltrifluoromethylation of ynones with the Langlois reagent is developed, providing a regio- and diastereoselective access to trifluoromethylated cyclopentanones under mild conditions.

Copper-Promoted Conjugate Addition of Carboxylic Acids to Ethenesulfonyl Fluoride (ESF) for Constructing Aliphatic Sulfonyl Fluorides

A CuO-promoted direct hydrocarboxylation of ethenesulfonyl fluoride (ESF) was developed using carboxylic acid as a nucleophile under mild conditions. A variety of molecules containing both ester group and aliphatic sulfonyl fluoride moiety exhibit great potential in medicinal chemistry and chemical biology. Furthermore, the modification of the known drugs Ibuprofen and Aspirin was also demonstrated.

Metal-free catalytic hydrocarboxylation of hexafluorobut-2-yne

An efficient method for stereoselective synthesis of trifluorinated enol esters catalyzed by base was introduced.

AIBN-Induced Remote Trifluoromethyl-Alkynylation of Thioalkynes

A novel α,α'-azobis(isobutyronitrile) (AIBN)-induced remote trifluoromethyl-alkynylation of thioalkynes with alkynyl triflones as both the trifluoromethyl and alkyne sources is described. Structurally diverse trifluoromethylated (Z)-enynes can be constructed with full control of regio-, stereo-, and site-selectivity, which serves as a highly selective method for the rapid construction of trifluoromethylated molecules.

Phosphine-Free Ru-Catalyzed Regio- and Stereoselective Addition of Benzoic Acids to Trifluoromethylated Alkynes toward Facile Access to Trifluoromethyl Group-Substituted (E)-Enol Esters

A combination of ruthenium catalyst with silver salt and copper salt was proved to be a highly efficient protocol for the direct addition reaction of benzoic acids with unsymmetrical trifluoromethylated internal alkynes. Diverse trifluoromethyl group-substituted (E)-enol esters were readily obtained for a broad substrate scope in moderate to good yields with excellent regio- and stereoselectivities under mild reaction conditions.

Electrochemical Minisci-type trifluoromethylation of electron-deficient heterocycles mediated by bromide ions

An electrochemical methodology for the Minisci-type trifluoromethylation of electron-deficient heterocycles mediated by cheap and easily available bromide ions has been developed.