Silver-Mediated Oxidative Aliphatic CH Trifluoromethylthiolation

N-Trifluoromethylthio-dibenzenesulfonimide: A Shelf-Stable, Broadly Applicable Electrophilic Trifluoromethylthiolating Reagent

The super electrophilicity of a shelf-stable, easily prepared trifluoromethylthiolating reagent N-trifluoromethylthio-dibenzenesulfonimide 7 was demonstrated. Consistent with the theoretical prediction, 7 exhibits reactivity remarkably higher than that of other known electrophilic trifluoromethylthiolating reagents. In the absence of any additive, 7 reacted with a wide range of electron-rich arenes and activated heteroarenes under mild conditions. Likewise, reactions of 7 with styrene derivatives can be fine-tuned by simply changing the reaction solvents to generate trifluoromethylthiolated styrenes or oxo-trifluoromethylthio or amino-trifluoromethylthio difunctionalized compounds in high yields.

AgSCF3-Mediated Oxidative Trifluoromethythiolation of Alkynes with Dearomatization to Synthesize SCF3-Substituted Spiro[4,5]trienones

A new method for the AgSCF3-mediated radical cascade difunctionalizing trifluoromethythiolation of alkynes with dearomatization is developed. This protocol provides a novel route to SCF3-substituted spirocyclic compounds via the formation of one C-SCF3 bond, one C-C bond, and one C-O double bond in a single step.

Difluoromethanesulfonyl hypervalent iodonium ylides for electrophilic difluoromethylthiolation reactions under copper catalysis

Difluoromethanesulfonyl hypervalent iodonium ylides 2 were developed as electrophilic difluoromethylthiolation reagents for a wide range of nucleophiles. Enamines, indoles, β-keto esters, silyl enol ethers and pyrroles were effectively reacted with 2 affording desired difluoromethylthio (SCF2H)-substituted compounds in good to high yields under copper catalysis. The reaction of allyl alcohols with 2 under the same conditions provided difluoromethylsulfinyl (S(O)CF2H) products in good yields. The difluoromethylthiolation of enamines is particularly effective with wide generality, thus the enamine method was nicely extended to the synthesis of a series of difluoromethythiolated cyclic and acyclic β-keto esters, 1,3-diketones, pyrazole and pyrimidine derivatives by a consecutive, two-step one-pot reaction using 2.

A visible-light-promoted radical reaction system for azidation and halogenation of tertiary aliphatic C-H bonds

A highly tunable radical-mediated reaction system for the functionalization of tertiary aliphatic C-H bonds was developed. Reactions of various substrates with the Zhdankin azidoiodane reagent 1, Ru(bpy)3Cl2, and visible light irradiation at room temperature gave C-H azidated or halogenated products in an easily controllable fashion. These reactions are efficient, selective, and compatible with complex substrates. They provide a potentially valuable tool for selectively labeling tertiary C-H bonds of organic and biomolecules with tags of varied chemical and biophysical properties for comparative functional studies.

Ag-catalyzed C-H/C-C bond functionalization

Silver, known and utilized since ancient times, is a coinage metal, which has been widely used for various organic transformations in the past few decades. Currently, the silver-catalyzed reaction is one of the frontier areas in organic chemistry, and the progress of research in this field is very rapid. Compared with other transition metals, silver has long been believed to have low catalytic efficiency, and most commonly, it is used as either a cocatalyst or a Lewis acid. Interestingly, the discovery of Ag-catalysis has been significantly improved in recent years. Especially, Ag(i) has been demonstrated as an important and versatile catalyst for a variety of organic transformations. However, so far, there has been no systematic review on Ag-catalyzed C-H/C-C bond functionalization. In this review, we will focus on the development of Ag-catalyzed C-H/C-C bond functionalization and the corresponding mechanism.

Enantioselective Trifluoromethylthiolating Lactonization Catalyzed by an Indane-Based Chiral Sulfide

Enantioselective trifluoromethylthiolation, especially of alkenes, is a challenging task. In this work, we have developed an efficient approach for enantioselective trifluoromethylthiolating lactonization by designing an indane-based bifunctional chiral sulfide catalyst and a shelf-stable electrophilic SCF3 reagent. The desired products were formed with diastereoselectivities of >99:1 and good to excellent enantioselectivities. The transformation represents the first enantioselective trifluoromethylthiolation of alkenes and the first enantioselective trifluoromethylthiolation that is enabled by a catalyst with a Lewis basic sulfur center.

Visible Light-Promoted Decarboxylative Di- and Trifluoromethylthiolation of Alkyl Carboxylic Acids

Described herein is a new and straightforward decarboxylative di- and trifluoromethylthiolation of alkyl carboxylic acids promoted by visible light. This approach enables the synthesis of biologically relevant alkyl SCF2H and SCF3 compounds from cheap and abundant carboxylic acids. The method is operationally simple, using irradiation from household light sources, and its mild reaction conditions make it tolerant of a range of functional groups. The strategy employs electrophilic phthalimide-derived di- and trifluoromethylthiolation reagents and exploits the ability of the imidyl radical to carry a radical chain.

Visible-Light-Promoted Trifluoromethylthiolation of Styrenes by Dual Photoredox/Halide Catalysis

Herein, we report a new visible-light-promoted strategy to access radical trifluoromethylthiolation reactions by combining halide and photoredox catalysis. This approach allows for the synthesis of vinyl-SCF3 compounds of relevance in pharmaceutical chemistry directly from alkenes under mild conditions with irradiation from household light sources. Furthermore, alkyl-SCF3-containing cyclic ketone and oxindole derivatives can be accessed by radical-polar crossover semi-pinacol and cyclization processes. Inexpensive halide salts play a crucial role in activating the trifluoromethylthiolating reagent towards photoredox catalysis and aid the formation of the SCF3 radical.

Quantitative Scale for the Trifluoromethylthio Cation-Donating Ability of Electrophilic Trifluoromethylthiolating Reagents

A new parameter, trifluoromethylthio cation-donating ability (Tt(+)DA), is introduced as a quantitative descriptor for the propensity of electrophilic trifluoromethylthiolating reagents to transfer a CF3S moiety in organic synthesis. The first Tt(+)DA scale of popular reagents has been established through DFT calculations. Excellent correlation has been identified between the Tt(+)DAs of N-SCF3-type reagents and the pKa of the corresponding acids, offering a powerful avenue for the rational design of novel reagents.

Silver-mediated oxidative trifluoromethylthiolation of cycloalkanols by C–C bond cleavage: a regioselective approach to distally trifluoromethylthiolated ketones

Various distally trifluoromethylthiolated ketones were readily prepared by silver-mediated oxidative trifluoromethylthiolation of cycloalkanols. The reaction features complete regioselectivity, operational simplicity, and excellent practicality.

Efficient catalytic α-trifluoromethylthiolation of aldehydes

An efficient organocatalytic method for α-trifluoromethylthiolation of aldehydes has been developed.

Aliphatic C–H azidation through a peroxydisulfate induced radical pathway

Transition-metal-free, chemo- and regioselective aliphatic tertiary C–H bond azidation with good functional group tolerance is described.

The medicinal chemist's toolbox for late stage functionalization of drug-like molecules

The advent of modern C–H functionalization chemistries has enabled medicinal chemists to consider a synthetic strategy, late stage functionalization (LSF), which utilizes the C–H bonds of drug leads as points of diversification for generating new analogs.

2-Trifluoromethylthiolation of glycals

The direct 2-trifluoromethylthiolation of glycals has been realized for the first time, benefiting the carbohydrate-based drug discovery.

Difluorocarbene-Derived Trifluoromethylthiolation and [(18)F]Trifluoromethylthiolation of Aliphatic Electrophiles

The first trifluoromethylthiolation and [(18)F]trifluoromethylthiolation of alkyl electrophiles with in situ generated difluorocarbene in the presence of elemental sulfur and external (radioactive) fluoride ion is described. This transition-metal-free approach is high yielding, compatible with a variety of functional groups, and operated under mild reaction conditions. The conceptual advantage of this exogenous-fluoride-mediated transformation enables unprecedented syntheses of [(18)F]CF3S-labeled molecules from most commonly used [(18)F]fluoride ions. The rapid radiochemical reaction time (≤1 min) and high functional-group tolerance allow access to a variety of aliphatic [(18)F]CF3S compounds in high yields.

Diaryl Selenide Catalyzed Vicinal Trifluoromethylthioamination of Alkenes

An efficient approach to vicinal trifluoromethylthioamination of alkenes with a broad substrate scope catalyzed by electron-rich diaryl selenide has been developed. This intermolecular amination strategy was successfully applied to SCF3-esterification of alkenes using weak acids as nucleophiles.

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.

Palladium(II)-catalyzed directed trifluoromethylthiolation of unactivated C(sp³)-H bonds

The synthesis of trifluoromethylthiolated aliphatic acid derivatives by Pd-catalyzed C(sp(3))-H bond functionalization was developed. Using a bidentate directing group, the direct and selective introduction of a SCF3 moiety was possible on a range of amides with remarkable selectivity for C(sp(3))-centers with an electrophilic SCF3 source and pivalic acid as an additive. This work constitutes an example of the unactivated C(sp(3))-SCF3 bond formation by C-H activation offering a new access to relevant molecules.

Direct radical trifluoromethylthiolation and thiocyanation of aryl alkynoate esters: mild and facile synthesis of 3-trifluoromethylthiolated and 3-thiocyanated coumarins

A facile oxidative radical cyclization of aryl alkynoate esters for the synthesis of 3-trifluoromethylthiolated and 3-thiocyanated coumarins is developed.