Oxidative Radical Intermolecular Trifluoromethylthioarylation of Styrenes by Arenediazonium Salts and Copper(I) Trifluoromethylthiolate

Efficient synthesis of SCF3-containing 3-alkenylquinoxalinones via three-component radical cascade reaction

An efficient and practical method for the synthesis of 3-alkenylquinoxalinones containing the SCF3 group has been readily developed through a three-component radical cascade reaction involving quinoxalinones, alkynes and AgSCF3. The reaction was found to be compatible with a variety of substrates and exhibited a high functional group tolerance and complete E-selectivity. The preliminary study suggests the involvement of a SCF3 radical in the transformation.

Copper-Catalyzed Enantioselective C(sp3 )-SCF3 Coupling of Carbon-Centered Benzyl Radicals with (Me4 N)SCF3

In contrast with the well-established C(sp2 )-SCF3 cross-coupling to forge the Ar-SCF3 bond, the corresponding enantioselective coupling of readily available alkyl electrophiles to forge chiral C(sp3 )-SCF3 bond has remained largely unexplored. We herein disclose a copper-catalyzed enantioselective radical C(sp3 )-SCF3 coupling of a range of secondary/tertiary benzyl radicals with the easily available (Me4 N)SCF3 reagent. The key to the success lies in the utilization of chiral phosphino-oxazoline-derived anionic N,N,P-ligands through tuning electronic and steric effects for the simultaneous control of the reaction initiation and enantioselectivity. This strategy can successfully realize two types of asymmetric radical reactions, including enantioconvergent C(sp3 )-SCF3 cross-coupling of racemic benzyl halides and three-component 1,2-carbotrifluoromethylthiolation of arylated alkenes under mild reaction conditions. It therefore provides a highly flexible platform for the rapid assembly of an array of enantioenriched SCF3 -containing molecules of interest in organic synthesis and medicinal chemistry.

Visible-Light-Driven Organophotocatalyzed Multicomponent Approach for Tandem C(sp3)-H Activation and Alkylation Followed by Trifluoromethylthiolation

A visible-light-driven organophotocatalyzed multicomponent approach has been developed for tandem direct C(sp³)-H activation and alkylation followed by trifluoromethylthiolation in a one-pot operation. We report a completely metal-free, tandem, three-component approach for the difunctionalization of activated alkenes via the photoinduced radical pathway. This protocol allows the formation of two new C(sp³)-C(sp³) and C(sp³)-SCF₃ bonds using a bench-stable, easy-to-handle trifluoromethylthiolating reagent under mild reaction conditions. The generosity of this reaction is shown with a library of C(sp³)-H donors and alkenes derivatives. The reaction conditions can tolerate a wide variety of functional groups. Gram-scale synthesis using environmentally benign and straightforward conditions highlights the synthetic advancement of the methodology. Further functionalization of the final product is also successfully demonstrated.

Current Advances in Meerwein-type Radical Alkene Functionalizations

Alkene functionalizations via Meerwein arylations are becoming increasingly attractive, especially since a variety of mild and sustainable methods for aryl radical generation are available today. This entails a broad spectrum of substrates and radical scavengers, as well as convenient synthetic routes to relevant precursors for further transformations. The present review focuses on recent advances in Meerwein-type alkene functionalizations and gives insights into the key mechanistic details of the respective reactions.

1 Introduction

2 Hydroarylation and Carboarylation

3 Carboamination, Carbooxygenation, and Carbothiolation

4 Carbohalogenation

5 Conclusion and Outlook

Recent advances in intermolecular 1,2-difunctionalization of alkenes involving trifluoromethylthiolation

Trifluoromethylthiolative difunctionalization of alkenes, a cheap and abundant feedstock, which installs a trifluoromethylthiol (SCF3) group and another unique functional group across the carbon-carbon double bonds, provides an ideal strategy for the preparation of β-functionalized alkyl trifluoromethyl sulfides and has become a hot topic recently. This review aims to summarize the major progress in this exciting research area, with particular emphasis on the mechanistic aspects of the reaction pathways.

Hypervalent iodine(iii)-promoted rapid cascade reaction for the synthesis of unsymmetric azo compounds

A rapid three-component cascade reaction for the synthesis of unsymmetric azo compounds via a radical activation strategy has been reported. Various aryldiazonium salts and unactivated alkenes are well compatible, providing the corresponding products in good to excellent yields. This strategy gives an efficient and practical solution for the synthesis of unsymmetric azo compounds with two C-N bond formation. A free radical pathway mechanism is advised for this transformation.

Metal-free visible-light-enabled vicinal trifluoromethyl dithiolation of unactivated alkenes

The difunctionalization of alkenes involving a trifluoromethylthio group (SCF3) for the conversion of versatile and readily available olefins into structurally more complex molecules has been successfully studied. However, the disproportionate dithiolation of alkenes is unknown. Herein, a transition-metal-free protocol is presented for the vicinal trifluoromethylthio-thiolation of unactivated alkenes via a radical process under mild conditions with a broad substrate scope and excellent tolerance.

Copper-catalyzed trifluoromethylthiolation-peroxidation of alkenes and allenes

Cu-catalyzed trifluoromethylthiolation-peroxidation of alkenes and allenes using AgSCF₃ and tert-butyl hydroperoxide has been developed. The method provides a variety of β-SCF₃ and β-vinyl-SCF₃ peroxides with excellent regio- and chemo-selectivities.

Intermolecular oxidative radical fluoroalkylfluorosulfonylation of unactivated alkenes with (fluoroalkyl)trimethylsilane, silver fluoride, sulfur dioxide and N-fluorobenzenesulfonimide

Reaction of unactivated alkenes affords various fluoroalkyl-containing alkyl sulfonyl fluorides with good functional group tolerance under mild conditions.

Visible-Light-Induced, Copper-Catalyzed Three-Component Coupling of Alkyl Halides, Olefins, and Trifluoromethylthiolate to Generate Trifluoromethyl Thioethers

Photoinduced, copper-catalyzed coupling reactions are emerging as a powerful method for generating Csp³-Y (Y = C or heteroatom) bonds from alkyl electrophiles and nucleophiles. Corresponding three-component couplings of alkyl electrophiles, olefins, and nucleophiles have the potential to generate an additional Csp³-Y bond and to efficiently add functional groups to both carbons of an olefin, which serves as a readily available linchpin. In this report, we establish that a variety of electrophiles and a trifluoromethylthiolate nucleophile can add across an array of olefins (including styrenes and electron-poor olefins) in the presence of CuI/binap and blue-LED irradiation, thereby generating trifluoromethyl thioethers in good yield. The process tolerates a wide range of functional groups, and an initial survey of other nucleophiles (i.e., bromide, cyanide, and azide) suggests that this three-component coupling strategy is versatile. Mechanistic studies are consistent with a photoexcited Cu(I)/binap/SCF₃ complex serving as a reductant to generate an alkyl radical from the electrophile, which likely reacts in turn with the olefin and a Cu(II)/SCF₃ complex to afford the coupling product.