Mild defluorinative -acrylation of amines with (trifluoromethyl)alkenes: synthesis of α-arylacrylamides.

A practical and efficient method for the -acrylation of amines with (trifluoromethyl)alkenes is achieved the cleavage of three C(sp)-F bonds, affording a diverse range of useful tertiary and secondary α-arylacrylamides in high yields. This protocol features mild conditions, is transition-metal free, operationally simple, gram-scalable, and compatible with valuable functional groups, and has a broad substrate scope. Mechanistic studies indicate that exchange of an oxygen atom happens between HO and NaOH, and that the oxygen atom is incorporated into the α-arylacrylamides the -defluorooxylation of the (trifluoromethyl)alkene.

Modular Synthesis of α-Aryl Acrylamido Carboxylic Acids by Triple C-F Bond Cleavage of (Trifluoromethyl)alkenes with Unprotected Amino Acids.

A straightforward and efficient strategy for the construction of tertiary and secondary α-aryl acrylamido carboxylic acids is reported. This N-acrylation protocol of unprotected amino acids is achieved by triple C-F bond cleavage of (trifluoromethyl)alkenes. This method features mild conditions, is operationally simple, is free of transition metals and racemization, can be used on a gram scale, and is compatible with various functional moieties.

Chemoselective Thioacylation of Amines Enabled by Synergistic Defluorinative Coupling.

A mild and chemoselective method for the thioacylation of amines, including amino acids and peptides, using -difluoroalkenes and sulfide, is reported. The distinguishing of the different nucleophilic sites (-site and diverse -sites) by the chemoselective C-F bond functionalization of -difluoroalkenes enables the unique synergistic defluorinative coupling reaction. This reaction features mild conditions, is operationally simple, efficient, and gram-scalable, tolerates various functional groups, and is activator-free and without racemization.

Fluoroolefins-Mediated Deoxygenative Substitution of Alcohols: Chemo- and Enantiospecific Construction of C-S, C-N, C-O, and C-Se Bonds.

For over half a century, by activation of alcohols with activators, deoxygenative substitution of alcohols has been limited to employing nucleophiles with a single nucleophilic site. Herein, we demonstrate a fluoroolefin-mediated deoxygenative substitution of nonactivated and activated alcohols with diverse acidic nucleophiles, with inversion of configuration, to allow chemo- and enantiospecific construction of C-S, C-N, C-O, and C-Se bonds by the distinction of the different nucleophilic sites of the nucleophiles. The formed -tethered monofluoroalkene was the intermediate.

Triple -defluoroetherification of (trifluoromethyl)alkenes with fluoroalkylated alcohols: access to fluoroalkylated orthoesters C(sp)-F bond cleavage.

The triple -defluoroetherification of (trifluoromethyl)alkenes with fluoroalkylated alcohols by C(sp)-F bond cleavage is reported, delivering various fluoroalkylated orthoesters in high yields. This reaction is transition-metal free and gram-scalable, features mild reaction conditions, and tolerates diverse functional groups.

Defluorinative Esterification and 1,3-Dietherification of (Trifluoromethyl)alkenes with Alcohols: Controlled Synthesis of α-Arylacrylates and 1,3-Diethers.

Purification-controlled defluorinative esterification and 1,3-dietherification of (trifluoromethyl)alkenes with alcohols are achieved, delivering various useful α-arylacrylates and 1,3-diethers in high yields. Remarkably, this reaction enables the cleavage of three C-F bonds in a CF group, and it is transition-metal free and catalyst-free, has simple operation, features mild conditions, is gram-scalable, and has broad substrate scope and valuable functional group tolerance. Mechanism studies indicated that the isolated monofluoroalkene-decorated 1,3-diethers are the intermediates, and the acidic property of silica gel assisted the defluorinative transformation of these 1,3-diethers to access α-arylacrylates with HO as the oxygen source.

Access to α,α-difluoro(arylthio)methyl oxetanes from α,α-difluoro(arylthio)methyl ketones and trimethylsulfoxonium halides: scope, mechanism and applications.

A general and practical method for the synthesis of α,α-difluoro(arylthio)methyl oxetanes that occurs by the reaction of α,α-difluoro(arylthio)methyl ketones with trimethylsulfoxonium halides is reported. This reaction proceeds the sequential Corey-Chaykovsky epoxidation and regioselective ring-expansion pathways and features mild conditions, operational simplicity, gram-scalability, a broad substrate scope and high yields. α,α-Difluoro(arylthio)methyl oxiranes have been shown to be the reaction intermediates.

α-Trifluoromethyl Carbanion-catalyzed Intermolecular Stetter Reaction of Aromatic Aldehydes with 2-Bromo-3,3,3-trifluoropropene: Synthesis of β-Alkoxyl-β-trifluoromethylated Ketones.

The intermolecular Stetter reaction of aromatic aldehydes with 2-bromo-3,3,3-trifluoropropene is achieved by the generated α-trifluoromethyl carbanion catalyst. It not only represents the first example for α-trifluoromethyl carbanion-catalyzed umpolung reaction but also reveals a new protocol for the umpolung of aldehydes. Various useful β-alkoxyl-β-trifluoromethylated ketones were obtained in high yields, which could further convert to attractive bioactive compounds.

Solvent-Switched Oxidation Selectivities with O : Controlled Synthesis of α-Difluoro(thio)methylated Alcohols and Ketones.

The solvent-switched hydroxylation and oxygenation of α-difluoro(thio)methylated carbanions with molecular oxygen under mild conditions are reported. This strategy tames the redox reactions of the in situ generated hydroperoxy difluoromethylsulfides, in which solvent-bonding can alter their reactivity and switch the oxidation selectivities. These controllable three-component reactions of gem-difluoroalkenes, thiols and molecular oxygen afford various useful α-difluoro(thio)methylated alcohols and ketones in high yields.

Regioselective Synthesis of 5-Trifluoromethylpyrazoles by [3 + 2] Cycloaddition of Nitrile Imines and 2-Bromo-3,3,3-trifluoropropene.

A general and practical method for the synthesis of 5-trifluoromethylpyrazoles is reported that occurs by the coupling of hydrazonyl chlorides with environmentally friendly and large-tonnage industrial feedstock 2-bromo-3,3,3-trifluoropropene (BTP). This exclusively regioselective [3 + 2] cycloaddition of nitrile imines and with BTP is catalyst-free and operationally simple and features mild conditions, high yields, gram-scalable, a broad substrate scope, and valuable functional group tolerance. Significantly, our method has been applied for the synthesis of the key intermediate of an active agonist of sphingosine 1-phosphate receptor.

Two C(sp)-F Bond Activation in a CF Group: -Defluorinative Amination Triggered 1,3-Diamination of (Trifluoromethyl)alkenes with Indoles, Carbazoles, Pyrroles, and Sulfonamides.

A novel strategy enabled cleavage of two C(sp)-F bonds in a CF group is reported. Triggered by -defluorinative amination, this 1,3-diamination of (trifluoromethyl)alkenes with indoles, carbazoles, pyrroles, and sulfonamides gave acyclic 1,3-diamine products bearing a monofluoroalkene moiety in high yields with good to excellent / selectivities. Preliminary mechanistic studies enable the isolation of the reaction intermediate and indicate that a unique sequential -/γ-selective defluorinative amination pathway is involved in this transformation.

Zn-ProPhenol Catalyzed Enantioselective Mannich Reaction of 2-Azirines with Alkynyl Ketones.

The enantioselective Mannich reaction of 2-azirines with alkynyl ketones is achieved under Zn-ProPhenol catalysis, delivering various aziridines with vicinal tetrasubstituted stereocenters in high yields with excellent enantioselectivities. The bimetallic Zn-ProPhenol complexes activate both the nucleophile and the electrophile in the same chiral pocket. A unique intramolecular hydrogen bond is observed in the obtained Mannich adducts, which lowers the basicity of the product's aziridine nitrogen thus favoring enantioselective control and allowing catalyst turnover.

Recent advances in three-component difunctionalization of -difluoroalkenes.

Three-component difunctionalization of alkenes is regarded as one of the most attractive strategies in synthetic chemistry, because it enables the direct synthesis of useful and complex molecules from simple and readily available starting materials in a step-economic manner. gem-Difluoroalkenes, as a class of useful and readily available fluorine-containing raw materials, have been well investigated in two-component coupling reactions. This review focuses on the progress of three-component difunctionalization reactions of gem-difluoroalkenes.

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. The ipso-defluorooxylation of (trifluoromethyl)alkenes with oximes is completely inhibited. A pesticidal active compound could be synthesized with our method.

Regioselective Synthesis of 3-Trifluoromethylpyrazole by Coupling of Aldehydes, Sulfonyl Hydrazides, and 2-Bromo-3,3,3-trifluoropropene.

A general and practical strategy for 3-trifluoromethylpyrazole synthesis is reported that occurs by the three-component coupling of environmentally friendly and large-tonnage industrial feedstock 2-bromo-3,3,3-trifluoropropene (BTP), aldehydes, and sulfonyl hydrazides. This highly regioselective three-component reaction is metal-free, catalyst-free, and operationally simple and features mild conditions, a broad substrate scope, high yields, and valuable functional group tolerance. Remarkably, the reactions could be performed on a 100 mmol scale and smoothly afforded the key intermediates for the synthesis of celecoxib, mavacoxib, SC-560, and AS-136A.

Fluorohalogenation of gem-Difluoroalkenes: Synthesis and Applications of α-Trifluoromethyl Halides.

A novel strategy for 1,2-dihalogenation of alkenes is reported that occurs through a sequential nucleophilic halide addition and electrophilic halogenation. By trapping the in situ generated unstable α-trifluoromethyl carbanion intermediates derived from the nucleophilic fluoride addition to electron-poor gem-difluoroalkenes, this fluorohalogenation of gem-difluoroalkenes with electrophilic haloalkynes affords various useful α-trifluoromethyl halides in high yields. A pesticidal active compound and various attractive trifluromethylated molecules could be smoothly synthesized from these obtained α-trifluoromethyl halides.

Copper-Catalyzed Intermolecular [4 + 2] Annulation Enabled by Internal Oxidant-Promoted C(sp)-H Functionalization: Access to 3-Trifluoromethylated 3-Hydroxy-cyclohexan-1-ones.

A copper-catalyzed diastereoselective [4 + 2] cyclolization of α,β-unsaturated ketoxime acetates and trifluoromethyl ketones affords various 3-trifluoromethylated 3-hydroxy-cylcohexan-1-ones smoothly. This reaction features the selective functionalization of a less acidic C(sp)-H bond by an internal oxdative C(sp)-H functionalization strategy. Preliminary investigations revealed that α,β-unsaturated ketoxime acetates were an internal oxidant, and the in situ generated HO served as the O-source of the carbonyl oxygen in the product.

Single C(sp)-F Bond Activation in a CF Group: Ipso-Defluorooxylation of (Trifluoromethyl)alkenes with Oximes.

The first defluorinative ipso-functionalization reaction of (trifluoromethyl)alkenes is reported. This exclusively regioselective ipso-defluorooxylation of (trifluoromethyl)alkenes with oximes affords various attractive O-(1,1-difluoroallyl)oxime ethers efficiently via a chemoselective single C(sp)-F bond activation in the CF group. Primary mechanism studies indicated an anionic S2-type substitution pathway might be involved in this transformation.

Intermolecular C(sp )-H Amination Promoted by Internal Oxidants: Synthesis of Trifluoroacetylated Hydrazones.

An intermolecular C(sp )-H amination reaction is reported that is promoted by internal oxidants and occurs via a C=N bond formation step. This intermolecular C(sp )-H amination reaction of trifluoromethyl ketones and aryldiazonium tetrafluoroborates affords various valuable trifluoroacetylated hydrazones in high yields with excellent E/Z selectivities. The salient features of this reaction type is that it is free of metal, catalyst, directing groups, and azides, and that it can be carried out under mild conditions, is operationally simple and efficient, gram-scalable, and it tolerates various functional groups.

Copper-Catalyzed Unstrained C-C Single Bond Cleavage of Acyclic Oxime Acetates Using Air: An Internal Oxidant-Triggered Strategy toward Nitriles and Ketones.

A copper-catalyzed aerobic oxidative C-C single bond cleavage of acyclic unstrained oxime acetates is reported, providing various aryl nitriles and ketones in good yields. Mechanistic studies indicate a radical procedure is involved in this transformation, and the oxygen atom in the ketone products is originated from O in the air. Oxime acetates as an internal oxidant have been proved to be an initiator, which may promote the discovery of novel protocol for C-C bond cleavage and dioxygen activation.

Two C-O Bond Formations on a Carbenic Carbon: Palladium-Catalyzed Coupling of N-Tosylhydrazones and Benzo-1,2-quinones To Construct Benzodioxoles.

A novel and efficient method for the formation of two C-O bonds on a carbenic carbon is reported. This palladium-catalyzed coupling of N-tosylhydrazones and benzo-1,2-quinones were involved the process of carbonyl ylides generation, aromatization, and intramolecular nucleophilic addition, delivering various useful benzodioxoles in high yields.

Nucleophilic trifluoromethylthiolation of bromoalkynones with AgSCF: C(sp)-SCF bond formation towards ynonyl trifluoromethyl sulfides.

An AgSCF mediated nucleophilic trifluoromethylthiolation reaction for C(sp)-SCF bond formation is reported. This nucleophilic trifluoromethylthiolation reaction of bromoalkynones afforded various useful ynonyl trifluoromethyl sulfides in high yields. Interestingly, the over-addition of AgSCF is avoided in our approach.

Conversion of Triple Bonds into Single Bonds in a Domino Carbopalladation with Norbornene.

A domino carbopalladation reaction of haloalkynes is presented. Remarkably, the four-time carbopalladation process converts the carbon-carbon triple bonds of haloalkynes stepwise into carbon-carbon double bonds, and finally to carbon-carbon single bonds. Features of this reaction are that the carbon-carbon double bonds of stable vinyl palladium intermediates are transformed into carbon-carbon single bonds with the generation of unstable alkyl palladium intermediates.