Trifluoromethylation of alkenes with concomitant introduction of additional functional groups

Copper-catalyzed enantioselective arylalkynylation of alkenes

Enantioselective aryl and alkynylation of activated/nonactivated alkenes.

A copper-catalyzed enantioselective arylalkynylation of alkenes with diaryliodonium salt and a monosubstituted alkyne is reported. The three-component coupling reactions proceed under mild reaction conditions with a broad substrate scope, leading to synthetically valuable 1,2-diaryl-3-butynes. The key to the success of this chemistry is the employment of the chiral bisoxazoline-phenylaniline (BOPA) ligand. A novel reaction pathway involving the phenyl radical generation under thermal copper catalysis is proposed according to mechanistic studies.

Direct C-H difluoromethylation of heterocycles via organic photoredox catalysis

The discovery of modern medicine relies on the sustainable development of synthetic methodologies to meet the needs associated with drug molecular design. Heterocycles containing difluoromethyl groups are an emerging but scarcely investigated class of organofluoro molecules with potential applications in pharmaceutical, agricultural and material science. Herein, we developed an organophotocatalytic direct difluoromethylation of heterocycles using O₂ as a green oxidant. The C–H oxidative difluoromethylation obviates the need for pre-functionalization of the substrates, metals and additives. The operationally straightforward method enriches the efficient synthesis of many difluoromethylated heterocycles in moderate to excellent yields. The direct difluoromethylation of pharmaceutical moleculars demonstrates the practicability of this methodology to late-stage drug development. Moreover, 2′-deoxy-5-difluoromethyluridine (F₂TDR) exhibits promising activity against some cancer cell lines, indicating that the difluoromethylation methodology might provide assistance for drug discovery.

Heterocycles containing difluoromethyl groups are molecules with potential application in pharmaceutical, agricultural and materials science. Here, the authors show an organophotocatalytic difluoromethylation of heterocycles using O₂ as green oxidant and preliminarily study the products’ bioactivity.

Synthesis of aziridines with multiple chiral substitutions by copper-catalyzed diastereoselective radical aminotrifluoromethylation of alkenes

A one-step catalytic and diastereoselective method for the synthesis of aziridines possessing multiple chiral substitutions by radical aminotrifluoromethylation of alkenes has been developed for the first time.

Iron-catalyzed acylation-functionalization of unactivated alkenes with aldehydes

Herein, an iron-catalyzed acylation-functionalization of unactivated alkenes with aldehydes via distal group ipso-migration is reported.

Access to cyano-substituted pyrazolines through copper-catalyzed cascade cyanation/cyclization of unactivated olefins

A mild copper-catalyzed cascade cyanation/cyclization of hydrazone-tethered unactivated olefins was developed for the efficient and practical synthesis of cyano-containing pyrazolines.

Recent progress of 1,1-difunctionalization of olefins

Olefins are a very important class of compounds and broadly used in the construction of various synthetic building blocks and practical industrial production. The difunctionalization of olefins provides one of the most powerful methods for the C-C or C-X bond formation with a rapid increase of the molecular complexity and synthetic value economically and effectively. Compared with the vigorous growth and abundant achievements of 1,2-difunctionalization of olefins, 1,1-difunctionalization is a relatively emerging and inadequately exploited research direction, despite being tremendously attractive from synthetic perspectives. In this minireview, we provide a brief overview of the advancements of 1,1-difunctionalization of olefins in the past twenty years, and prospects of future developments.

Three component hydroxyletherification and hydroxylazidation of (trifluoromethyl)alkenes: access to α-trifluoromethyl β-heteroatom substituted tertiary alcohols

The three component hydroxyletherification and hydroxylazidation reactions of (trifluoromethyl)alkenes are reported, providing various useful α-trifluoromethyl β-heteroatom substituted tertiary alcohols in high yields.

Transition-metal-free trifluoromethylative difunctionalization of olefins and alkynes: approaches and challenges ahead

Transition metal free trifluoromethylative difunctionalization of olefins and alkynes represents one of the most efficient methods to generate pharmaceutically and agrochemically important organofluoride compounds.

Iron-catalyzed three-component intermolecular trifluoromethyl-acyloxylation of styrenes with NaSO2CF3 and benzoic acids

A new iron-catalyzed intermolecular three-component trifluoromethyl-acyloxylation of styrenes has been developed with a broad substrate scope under mild conditions.

Recent advances in three-component difunctionalization of gem-difluoroalkenes

Three-component difunctionalization of gem-difluoroalkenes via the generation and transformation of a α-fluoroalkylated carbanion, a carbon–metal species, a radical, and a carbocation intermediate.

Transition-metal-free synthesis of CMe2CF3-containing chroman-4-ones via decarboxylative trifluoroalkylation

(NH₄)₂S₂O₈-mediated decarboxylative trifluoroalkylation of alkenes with 3,3,3-trifluoro-2,2-dimethylpropanoic acid under metal-free conditions has been described.

Rhenium-catalyzed alkylarylation of alkenes with PhI(O2CR)2via decarboxylation to access indolinones and dihydroquinolinones

Rhenium-catalyzed alkylarylation of alkenes with hypervalent iodine(iii) reagents (HIRs) via decarboxylation to access various 3,3-disubstituted indolinones and trans-3,4-dihydroquinolinones is described.

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.

Acid promoted radical-chain difunctionalization of styrenes with stabilized radicals and (N,O)-nucleophiles

A radical chain difunctionalization of styrenes does not require a catalyst, but activation of benzoyl peroxide by a strong acid.

Electrochemical trifluoromethylation/semipinacol rearrangement sequences of alkenyl alcohols: synthesis of β-CF3-substituted ketones

Electrochemical oxidative radical trifluoromethylation/semipinacol rearrangement sequences of alkenyl alcohols were developed in this study. This approach is environmentally benign and uses the shelf-stable Langlois reagent as a trifluoromethyl radical precursor and electrons as the oxidizing reagents. The present protocol offers a facile route to prepare β-trifluoromethylated ketone derivatives.

Regioselective Chlorolactonization of Styrene-Type Carboxylic Esters and Amides via PhICl2-Mediated Oxidative C-O/C-Cl Bond Formations

A facile method employing styrene-type carboxylic esters or amides in the presence of PhICl₂ in CH₃CN was developed to achieve the synthesis of 6-endo products 3,4-dihydroisocoumarins or 3,4-dihydroisocoumarin-1-imines in good to high yields. This metal-free regioselective intramolecular chlorolactonization process was proposed to involve a PhICl₂-mediated oxidative C-O bond formation followed by C-Cl bond formation.

Photocatalytic hydroacylation of trifluoromethyl alkenes

Hydrofunctionalization of trifluoromethyl alkenes is highly challenging, because the nucleophilic addition is oftentimes followed by β-F elimination in this case. By the use of tetrabutylammonium decatungstate (TBADT) as a hydrogen-atom-transfer (HAT) photocatalyst for acyl C-H activation, we successfully avoid the β-F elimination in the hydroacylation of trifluoromethyl alkenes with aldehydes. This light (390 nm) promoted reaction provides a facile and efficient access to various β-CF3 ketones in complete regiocontrol with high functionality tolerance and 100% atom economy.

Silver-Catalyzed Decarboxylative Alkylfluorination of Alkenes

A decarboxylation of alkyl carboxylic acids for alkylfluorination of alkene was developed, with the catalysis of silver(I) and Selectfluor as both the oxidant and fluorine source. This reaction is highly chemoselective, producing the decarboxylative alkylfluorination products rather than the competitive fluorination of aliphatic carboxylic acids. This practical transformation proceeds efficiently in aqueous media at room temperature and exhibits a large range of functional-group tolerance in various primary and secondary aliphatic carboxylates and alkenes.

Catalytic Asymmetric Synthesis of α,α-Difluoromethylated and α-Fluoromethylated Tertiary Alcohols

The catalytic asymmetric synthesis of α,α-difluoromethylated tertiary alcohols is described, using an asymmetric dihydroxylation reaction. This protocol using either the AD-mix-α or AD-mix-β allowed an easy access to these valuable fluorinated chiral building blocks, which have been obtained with excellent yields and er. In addition, the reaction was extended to the α-fluoromethylated analogues.

N-Heterocyclic Carbene-Catalyzed Radical Relay Enabling Vicinal Alkylacylation of Alkenes

The N-heterocyclic carbene-catalyzed radical relay enables the vicinal alkylacylation of styrenes, acrylates and acrylonitrile using aldehydes and tertiary alkyl carboxylic acid-derived redox-active esters. This protocol introduces tertiary alkyl groups and acyl groups to C-C double bonds with complete regioselectivity to produce functionalized ketone derivatives. The radical relay mechanism involves single electron transfer from the enolate form of a Breslow intermediate and radical addition of the resultant alkyl radical to the alkene followed by radical-radical coupling.

Selective single C-F bond arylation of trifluoromethylalkene derivatives

Through an S_N2′ amination, N-alkylation and palladium-catalyzed allylic substitution sequence, we realized ipso-C–F bond arylation/alkenylation of trifluoromethylalkene derivatives.

A strategically novel single C–F bond functionalization of CF₃-derived molecules, which shows a prominent advantage for the expedient construction of difluoromethylene-bridged organic scaffolds, is disclosed. The reported protocol consists of S_N2′ amination, N-alkylation and palladium-catalyzed allylic substitution reactions, which enables straightforward arylation and alkenylation of vinyltrifluoromethane derivatives. Furthermore, this strategy is characterized by its broad substrate scope with respect to both CF₃-alkene and arylboronic acid derivatives.

Electrochemical Difluoromethylation of Electron-Deficient Alkenes

Electrochemical 1,2-hydroxydifluoromethylation and C-H difluoromethylation of acrylamides were developed by using CF₂ HSO₂ NHNHBoc as the source of the CF₂ H group. These electricity-powered oxidative alkene functionalization reactions do not need transition-metal catalysts or chemical oxidants. The reaction outcome, 1,2-difuntionalization or C-H functionalization, is determined by the substituents on the amide nitrogen atom of the acrylamides instead of by the reaction conditions.