Cu(III)–CF3 Complex Enabled Unusual (Z)-Selective Hydro-trifluoromethylation of Terminal Alkynes

Synthesis of Trifluoromethylated Alkenes via a Tandem Aldol/N-Acyloxyphthalimide-Assisted Decarboxylation Sequence

We have developed a metal-free approach for synthesizing E-trifluoromethylated alkenes from readily available aldehydes and the N-hydroxyphtalimide ester of trifluoropropionic acid. To address the challenge of defluorination, we conducted high-throughput screening of reaction conditions. We discovered that acid-base co-catalysis effectively suppresses defluorination, thereby enhancing product yields. A key advantage of our method is its reliance on inexpensive, commercially available starting materials and straightforward reaction conditions.

A Convergent, Modular Approach to Trifluoromethyl-Bearing 5-Membered Rings via Catalytic C(sp3 )-H Activation

Trifluoromethyl-bearing 5-membered rings are prevalent in bioactive molecules, but modular approaches to these compounds by functionalization of robust C(sp³ )-H bonds in a direct and selective manner are extremely challenging. Herein we report the rhodium-catalyzed α-CF₃ -α-alkyl carbene insertion into C(sp³ )-H bonds of a broad range of substrates to access 7 types of CF₃ -bearing saturated 5-membered carbo- and heterocycles. The reaction is particularly effective for benzylic C-H insertion exerting good site-, diastereo- and enantiocontrol, and applicable to the synthesis of chiral CF₃ analogues of bioactive molecules. Ruthenium α-CF₃ -α-alkyl carbene complexes underwent stoichiometric reactions to give C-H insertion products, lending evidence for the involvement of metal α-CF₃ -α-alkyl carbene species in the catalytic cycle. DFT calculations revealed that the π⋅⋅⋅π attraction and intra-carbene C-H⋅⋅⋅F hydrogen bond elucidate the origin of selectivity of the benzylic C-H insertion reactions.

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.

Renewable Electricity Enables Green Routes to Fine Chemicals and Pharmaceuticals

Syntheses of chemicals using renewable electricity and when generating high atom economies are considered green and sustainable processes. In the present state of affairs, electrochemical manufacturing of fine chemicals and pharmaceuticals is not as common place as it could be and therefore, merits more attention. There is also a need to turn attention toward the electrochemical synthesis of valuable chemicals from recyclable greenhouse gases that can accelerate the process of circular economy. CO₂ emissions are the major contributor to human-induced global warming. CO₂ conversion into chemicals is a valuable application of its utilisation and will contribute to circular economy while maintaining environmental sustainability. Herein, we present an overview of electro-carboxylation, including mechanistic aspects, which forms carboxylic acids using molecular carbon dioxide. We also discuss atom economies of electrochemical fluorination, methoxylation and amide formation reactions.

Atom-Economical Thiocyanation-Amination of Alkynes with N-Thiocyanato-Dibenzenesulfonimide

A highly regioselective protocol for intermolecular thiocyanation-amination of alkynes by N-thiocyano-dibenzenesulfonimide (NTSI) as the SCN and nitrogen sources has been developed. A C-S bond and C-N bond are simultaneously constructed in only one step. The reaction under simple mild conditions features a broad substrate scope, atom economy, high yields (up to 94%), and excellent functional group tolerance.

(Z)-Trifluoromethyl-Trisubstituted Alkenes or Isoxazolines: Divergent Pathways from the Same Allene

Because of a charge-dipole interaction involving nonbonding electron pairs on fluorine, protonation of trifluoromethyl allenes leads to tri- or tetrasubstituted alkenes with high (Z)-selectivity. Treatment of the same allenes with catalytic Au(I) initiates a reaction cascade that produces isoxazolines in high yield.

Isolation of OH-bridged Ag(i)/Cu(iii) and ion-pair Cu(i)/Cu(iii) trifluoromethyl complexes with monophosphines

An unusual Ag(i)–Cu(iii) trifluoromethyl complex is isolated and characterized, featuring linear Ag(i) and square planar Cu(iii) units that are bridged by a hydroxide ligand.

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

A general and selective syn-carboxylation-trifluoromethylation across the triple bond of terminal alkynes is developed by virtue of a reactive Cu(iii)–CF₃ complex, which produces a broad range of biologically active trifluoromethylated enol esters with excellent regio- and stereoselectivity.