Two C(sp3)-F Bond Activation in a CF3 Group: ipso-Defluorinative Amination Triggered 1,3-Diamination of (Trifluoromethyl)alkenes with Indoles, Carbazoles, Pyrroles, and Sulfonamides

Mild [3 + 3] Annulation of (Trifluoromethyl)alkenes with Thioureas Enabled by Chemoselective Defluorinative Amination: Synthesis of 6-Fluoro-3,4-dihydropyrimidine-2(1H)-thiones

The chemoselective defluorinative [3 + 3] annulation of (trifluoromethyl)alkenes with thioureas is reported. This protocol affords various attractive 6-fluoro-3,4-dihydropyrimidine-2(1H)-thiones in high yields, features transition-metal free, mild conditions, efficient, is operationally simple and gram-scalable, tolerates diverse useful functional groups.

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

A practical and efficient method for the N-acrylation of amines with (trifluoromethyl)alkenes is achieved via the cleavage of three C(sp3)-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 H2O and NaOH, and that the oxygen atom is incorporated into the α-arylacrylamides via the ipso-defluorooxylation of the (trifluoromethyl)alkene. This method is also applied in the late-stage N-acrylation of pharmaceuticals.

Defluorinative Diazolation-Cyclization Relay for Synthesis of Furan-Bridged Triheterocycles and Colorimetric Sensor Application

Polyaromatics, as the assembly of diverse cyclic π-systems, exhibit unique physicochemical properties when compared to their individual constituents. In this study, we developed a strategic connection of two azacycles via a furan bridge through a defluorinative diazolation-cyclization reaction of trifluoromethyl enones and N-heterocycles. A range of modular 2,4-furan-bridged triheterocycles (FBTHs), featuring a C3-trifluoromethyl group, was synthesized with broad substrate scope and good regioselectivity under transition metal-free conditions. This three-component protocol was achieved through successive C(sp3)-F bond functionalization of one trifluoromethyl group, which is recognized for its stability and durability. Moreover, the synthetically useful functionalities such as bromide and formyl group could be easily installed on the resulting products, and the imidazole-containing FBTH could serve as a valuable ligand in the preparation of an advanced colorimetric sensor, thereby underscoring their potential applications.

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. Mechanistic studies indicate that oxygen atom exchange happens among H2O, NaOH, and amino acids, and the oxygen atom of the amide moiety of the product is incorporated by the ipso-defluorooxylation of (trifluoromethyl)alkene.

Photoredox-Catalyzed Sequential Decarboxylative/Defluorinative Aminoalkylation of CF3-Alkenes with N-Arylglycines

A photoredox-catalyzed sequential decarboxylative/defluorinative aminoalkylation of CF3-alkenes with N-arylglycines is described. This metal-free and redox-neutral protocol provided efficient access to the monofluoroalkenyl-1,5-diamines in good yields with excellent functional group compatibility. Mechanistic studies revealed that the reaction proceeds via a radical pathway with the gem-difluoroalkenyl amine as an intermediate.

Transition-Metal-Free Hydrodefluoroamination of Trifluoromethyl Enones for the Synthesis of α-Fluoroenamides

A three-component strategy was developed to enable hydrodefluoroamination of β-trifluoromethyl enones by selectively activating two C(sp3)-F bonds in the trifluoromethyl group. The method involved a sequence of carbonyl reduction, hydrodefluorination, and defluoroamination under transition-metal-free conditions. Synthetically useful (E)-stereospecific α-fluoroenamides were obtained in good yields with diverse functional group tolerance, which could be easily transformed into valuable organofluorides and heterocycles. The carbonyl auxiliary exerts both electronic and steric impacts on the CF3-alkenes, allowing for controllable and selective defluorination.

Picking Two out of Three: Defluorinative Annulation of Trifluoromethyl Alkenes for the Synthesis of Monofluorinated Carbo- and Heterocycles

The increasing demand of organofluorine compounds in medicine, agriculture, and materials sciences makes sophisticated methods for their synthesis ever more necessary. Nowadays, not only the C-F bond formation but also the selective C-F bond cleavage of readily available poly- or perfluorine-containing compounds have become powerful tools for the effective synthesis of organofluorine compounds. The defluorinative cross-coupling of trifluoromethyl alkenes with various nucleophiles or radical precursors in an SN 2' manner is a convergent route to access gem-difluoroalkenes, which in turn react with nucleophiles or radical precursors via an SN V-type reaction. If the SN V reactions occur intramolecularly, the dual C-F bond cleavage of trifluoromethyl alkenes allows facile assembly of monofluorinated cyclic skeletons with structural complexity and diversity. In this personal account, we summarized the advances in this field on the basis of coupling and cyclization partners, including binucleophiles, alkynes, diradical precursors and radical precursors bearing a nucleophilic site. Accordingly, the annulation reactions can be achieved by base-mediated sequential SN 2'/SN V reactions, transition metal catalyzed or mediated reactions, photoredox catalysis, and the combination of photocatalytic reactions with SN V reaction. In the context of seminal works of others in this field, a concise summary of the contributions of the authors is also offered.

Solvent-Controllable C-F Bond Activation for Masked Formylation of α-Trifluoromethyl Alkenes via Organo-Photoredox Catalysis

A solvent-controllable organo-photoredox-catalyzed C-F bond activation for masked formylation of α-trifluoromethyl alkenes with low-priced 1,3-dioxolane as masked formyl radical equivalent has been described. Consequently, a diversity of masked formylated gem-difluoroalkenes and monofluoroalkenes are constructed in moderate to high yields. This approach merits readily available starting materials, mild reaction conditions, and broad substrate scope. The feasibility of this approach has been highlighted by the one-pot masked formylation/hydrolysis sequence to form γ,γ-difluoroallylic aldehydes and late-stage modification of pharmaceutical and natural product derivatives.

Selective and controllable amination and defluoroamidation of α-trifluoromethylstyrene

We present a blueprint for the amination and defluoroamidation of α-trifluoromethylstyrene. This practical protocol presents a general method for the diversity-oriented synthesis of vicinal trifluoromethyl amines and gem-difluoro alkenes from α-trifluoromethylstyrene maintaining excellent chemoselectivity. The synthetic strategy features outstanding atom economy and wide functional group tolerance under mild reaction conditions.

Base-Mediated α-gem-Difluoroalkenylations of Aldehydes and Ketones

Herein, we present a base-mediated nucleophilic substitution reaction of α-trifluoromethylstyrenes with simple silyl enol ethers, enabling the efficient synthesis of carbonyl-substituted gem-difluoroalkenes. The merit of this protocol is exhibited by its mild reaction conditions, broad substrate scope, and scalable preparation. Notably, this method demonstrates its applicability for late-stage functionalization of structurally complex molecules. Moreover, we illustrate that the resulting products can serve as valuable precursors for the synthesis of diverse medicinally relevant compounds.

Combining Hydrodefluorination and Defluorophosphorylation for Chemo- and Stereoselective Synthesis of gem-Fluorophosphine Alkenes

A chemo-, regio-, and stereoselective reaction of trifluoromethyl enones, phenylsilane, and phosphine oxides through a sequential hydrodefluorination and defluorophosphorylation relay is developed for the synthesis of distinctive gem-fluorophosphine alkenes. This multicomponent reaction occurred under transition-metal-free conditions with good functional group tolerance. Moreover, the preinstalled carbonyl auxiliary is important for tuning the reactivity of β-trifluoromethyl enones, thereby enabling controllable and selective functionalization of two fluorine atoms in trifluoromethylated enones.

Controllable Synthesis of Trifluoromethyl- or gem-Difluorovinyl-containing Analogues of Neonicotinoids by the Reaction of α-(Trifluoromethyl)styrenes with 2-Nitroimino-imidazolidine

A simple and straightforward addition or defluorination of α-(trifluoromethyl)styrenes with 2-nitroimino-imidazolidine (2a), 2-(nitromethylene)imidazolidine (2b), 2-cyanoimino-thiazolidine (2c), and (E)-1-methyl-2-nitroguanidine (2d), in a controlled manner, was developed. The hydroamination of α-(trifluoromethyl)styrenes with 2a, 2b, 2c, and 2d was completed in the presence of DBN at room temperature within 0.5-6 h, affording structurally diverse β-trifluoromethyl-β-arylethyl analogues of neonicotinoids in moderate to good yields. The γ,γ-difluoro-β-arylallyl analogues of neonicotinoids were also successfully synthesized via defluorination of α-(trifluoromethyl)styrenes, with 2a and 2c using NaH as base at an elevated temperature together with a prolonged reaction time of 12 h. The method features simple reaction setup, mild reaction conditions, broad substrate scope, high functional group compatibility, and easy scalability.

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 CF₃ 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 H₂O as the oxygen source.

Defluorinative Transformation of (2,2,2-Trifluoroethyl)arenes Catalyzed by the Phosphazene Base t-Bu-P2

In this study, we demonstrated that 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ5,4λ5-catenadi(phosphazene) (t-Bu-P2) catalyzes the defluorinative functionalization reactions of (2,2,2-trifluoroethyl)arenes with alkanenitriles to produce monofluoroalkene products. The reaction proceeds through HF elimination from a (2,2,2-trifluoroethyl)arene to form a gem-difluorostyrene intermediate, which is followed by nucleophilic addition of an alkanenitrile and elimination of a fluoride anion. The catalysis is compatible with a variety of functional groups.

Synthesis of CF3-Substituted Alkylamines, 1,2-Bisazoles, and 1,4,5,6-Tetrahydro-1,2,4-triazines from Newly Designed Tetrazole-Activated Trifluoromethyl Alkenes

A new class of Michael acceptor, tetrazolyl-trifluoromethyl alkenes, has been discovered. They readily undergo Michael-type addition instead of addition-elimination reaction with aliphatic amines and azoles to furnish β-trifluoromethyl alkylamines and CF₃-substituted 1,2-bisazole derivatives, respectively. Additionally, some of the products are capable of engaging in microwave-assisted intramolecular denitrogenative annulation, leading to the formation of CF₃-substituted 1,4,5,6-tetrahydro-1,2,4-triazines that are otherwise difficult to access by other methodologies.

Superbase-Mediated gem-Difluoroalkenylations of Sulfoximines

At ambient temperature, deprotonated sulfoximines react with 1-trifluoromethylalkenes to provide either N- or C-gem-difluoroalkenylated products. The reaction site depends upon the N substituent of the starting material. The optimal conditions involve the use of a superbasic system NaOH in dimethyl sulfoxide. The reactions are characterized by a broad substrate scope and medium to high yields. Scale-up experiments of both the N- and C-gem-difluoroalkenylations proceeded well. Treatment of a N-difluoroallyl sulfoximine with an aryl thiol under dioxygen afforded the corresponding oxygenated addition product.

Selective C-F Bond Etherification of Trifluoromethylalkenes with Phenols

Selective functionalization of a single sp³ C-F bond of the CF₃ group represents an appealing way to generate the pharmaceutically privileged difluoromethylene moiety. Herein, a novel protocol for the C-F bond etherification of trifluoromethylalkenes and phenols is reported. A variety of alkenyl difluoroaryloxy ethers are obtained with good chemoselectivity and functional group tolerance. DFT calculation results and control experiments suggest that metal ion Cs⁺ might be involved in this defluorooxylation. Furthermore, the desired product exhibits a good insecticidal activity.

Screening of indole derivatives as the potent anticancer agents on dihydrofolate reductase: pharmaco-informatics and molecular dynamics simulation

Dihydrofolate reductase (DHFR) is a ubiquitous cellular enzyme involved in the biosynthesis of nucleotide and protein precursors, thus, the inhibition of human DHFR can be a promising strategy in cancer treatment. The design of effective anticancer drugs is an urgent need today according to the high spread of cancer. The indole molecule with diverse mechanisms of action and anticancer properties is one of the efficient pharmacophores in drug design. Hence, a virtual library of indole derivatives as a scaffold was selected for designing safer and more effective anticancer drugs against DHFR in this work. All indole derivatives utilized in the library design were selected regarding appreciable tumor growth inhibition. Structure-activity relationship (SAR), docking energy, ADMET (absorption, distribution, metabolism, excretion, and toxicity) parameters, and effective non-covalent interactions were used to identify potential anticancer with indole scaffold. Results showed a higher number of indole moieties provide a strong attachment to the DHFR binding pocket and therefore more effective anticancer activity. The indole scaffold in combination with dichlorobenzene improves DHFR inhibition whereas barbituric acid weakens inhibition activity. In the following to validate the docking results, Molecular dynamics (MD) simulation and molecular mechanics generalized-Born surface area (MM-GBSA) indicated the permanent stability of the selected ligands into the DHFR binding pocket and the key amino acids. Therefore, promising pharmacophores based on indole-DHFR interactions were discovered, and the outcome could be useful in guiding future in vitro and in vivo drug discovery in cancer medicine.Communicated by Ramaswamy H. Sarma.

DBN-Mediated Addition Reaction of α-(Trifluoromethyl)styrenes with Diazoles, Triazoles, Tetrazoles, and Primary, Secondary, and Secondary Cyclic Amines

A mild and efficient DBN-mediated addition reaction of α-(trifluoromethyl)styrenes with diazoles, triazoles, tetrazoles, and primary, secondary, and secondary cyclic amines was developed. This practical protocol provided a robust method for the synthesis of various β-trifluoromethyl nitrogen-containing heterocycles and β-trifluoromethyl amines.

Chemo- and regioselective defluorinative annulation of (trifluoromethyl)alkenes with pyrazolones: synthesis and insecticidal activity of 6-fluoro-1,4-dihydropyrano[2,3-c]pyrazoles

The chemo- and regioselective defluorinative [3 + 3] annulation of (trifluoromethyl)alkenes and pyrazolones gives useful 6-fluoro-1,4-dihydropyrano[2,3-c]pyrazoles.

Bond Energy Enabled Amines Distinguishing: Chemo-, Regioselective 1,3-Diamination of (Trifluoromethyl)alkenes with Different Amines by Two C(sp3)-F Bonds Cleavage

The methods to distinguish different amines are rarely investigated. In this manuscript, a bond energy enabled amines distinguishing strategy is reported. With (trifluoromethyl)alkenes as linchpins, a chemo-, regioselective three-component defluorinative...

Selective C-F Bond Allylation of Trifluoromethylalkenes

Selective C-F bond functionalization of CF₃ group represents an appealing strategy for the incorporation of pharmaceutically privileged difluoromethylene moiety. Despite the recent significant advancement attained in the functionalization of Ar-CF₃ molecules, prescriptions amenable for alkenyl-CF₃ congeners remain sufficiently inadequate. Herein, we report a strategically novel protocol for the C-F bond elaboration of trifluoromethylalkene derivatives. By using readily available allyl metallics as nucleophilic coupling partner, the present reaction enables an expedient construction of structurally diversified CF₂ -bridged 1,5-dienes. Furthermore, the exquisite selectivity observed in this transformation is revealed to be based on the underlying mechanism that consists of a cascade of nucleophilic S_N 2' defluorinative allylation and electronically promoted Cope rearrangement.

Synthesis of CF3-Containing Linear Nitriles from α-(Trifluoromethyl)styrenes

Four unprecedented base-catalyzed/mediated nucleophilic additions of TMSCN to α-(trifluoromethyl)styrenes and 2-trifluoromethyl enynes were developed. The reaction proceeded smoothly at room temperature under mild and transition-metal-free conditions without affecting the trifluoromethyl group and afforded the corresponding CF₃-containing alkyl, alkynyl, and butadienyl nitriles in moderate to excellent yields in a highly regioselective manner, respectively.