Carbon-carbon bond cleavage for Cu-mediated aromatic trifluoromethylations and pentafluoroethylations

Copper-Catalyzed Aromatic Trifluoromethylation and the Related Transformations

Trifluoromethylated aromatic compounds (Ar-CF3 ) are the substances of considerable interest in various industrial fields. The high lipophilicity, strong electron-withdrawing ability, and characteristic size of trifluoromethyl group are key influences in biologically active molecules. Due to these attractive properties, the benzotrifluoride structural motifs have been widely employed in the design of pharmaceuticals, agrochemicals, dyes, liquid crystals, and polymers. Therefore, the development of highly efficient methodologies for aromatic trifluoromethylation is of significant importance for wide fields of science and technology. Recently, a great deal of attention has been paid to catalytic protocols to introduce fluoroalkyl groups into aromatic rings selectively. This personal account highlights the copper-mediated aromatic trifluoromethylation and the related transformations developed by our research group.

Perfluorocarboxylic Anhydrides Triggered Cyclization: Access to 4-Perfluoroalkylpyridines

A double nucleophilic addition-cyclization-elimination cascade is developed, that allows various 2,6-diaryl-4-perfluoroalkylpyridines to be synthesized in one step from easily available enamides and perfluorocarboxylic anhydrides. The procedure is also operationally simple and scalable and provides access to the facial construction of 4-fluoroalkylpyridines, which are of great interest in medicinal chemistry.

From C1 to C2 : TMSCF3 as a Precursor for Pentafluoroethylation

A highly efficient copper-mediated aromatic pentafluoroethylation method using TMSCF₃ as the sole fluoroalkyl source is described. The reaction proceeds by a key C₁ to C₂ process, that is, the generation of CuCF₃ from TMSCF₃ , followed by a subsequent spontaneous transformation into CuC₂ F₅ . Various aryl iodides were pentafluoroethylated with the TMSCF₃ -derived CuC₂ F₅ . This method represents the first practical and efficient method for pentafluoroethylation of aryl iodides using commercially available TMSCF₃ as a pentafluoroethyl precursor.

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

The catalytic asymmetric methylation of fluoroalkylated pyruvates is shown with dimethylzinc as a methylating reagent in the presence of a copper catalyst bearing a chiral phosphine ligand. This is the first catalytic asymmetric methylation to synthesize various α-fluoroalkylated tertiary alcohols with CF₃, CF₂H, CF₂Br, and n-C _n F_2n+1 (n = 2, 3, 8) groups in good-to-high yields and enantioselectivities. Axial backbones and substituents on phosphorus atoms of chiral phosphine ligands critically influence the enantioselectivity. Moreover, the methylation of simple perfluoroalkylated ketones is found to be facilitated by only chiral phosphines without copper.

Trifluoroethoxy-Coated Phthalocyanine Catalyzes Perfluoroalkylation of Alkenes under Visible-Light Irradiation

We disclose herein the perfluoroalkylation of alkenes catalyzed by trifluoroethoxy-coated zinc phthalocyanine under irradiation of visible light. Perfluoroalkyl iodides were nicely incorporated into unsaturated substrates, including alkyne, to provide perfluoroalkyl and iodide adducts in moderate to good yields. Trifluoromethylation is also possible by trifluoromethyl iodide under the same reaction conditions. The mechanistic study is discussed.

The first nucleophilic C–H perfluoroalkylation of aromatic compounds via (arene)tricarbonylchromium complexes

Complexed and reversibly activated arenes selectively react with a perfluoroalkyl anion under mild conditions, forming cyclohexadienyl adducts that readily undergo oxidation to perfluoroalkyl arenes.

Copper-Catalyzed Difluoromethylation of Aryl Iodides with (Difluoromethyl)zinc Reagent

The combination of difluoroiodomethane and zinc dust or diethylzinc can readily lead to (difluoromethyl)zinc reagents. Therefore, the first copper-catalyzed difluoromethylation of aryl iodides with the zinc reagents is accomplished to afford the difluoromethylated arenes. The reaction proceeds efficiently through the ligand/activator-free operation without addition of ligands for copper catalyst (e.g., phen and bpy) and activators for zinc reagent (e.g., KF, CsF, and NaO-t-Bu). Moreover, transmetalation of the CF2H group from zinc reagent to copper catalyst proceeds even at room temperature to form the cuprate [Cu(CF2H)2](-).

Siladifluoromethylation and Difluoromethylation onto C(sp(3)), C(sp(2)), and C(sp) Centers Using Ruppert-Prakash Reagent and Fluoroform

Siladifluoromethylations and difluoromethylations on sp(3), sp(2), and sp carbons of lithiated carbamates, arenes, and terminal alkynes, respectively, have been attained by employing the Ruppert-Prakash reagent (CF3TMS) and fluoroform (CF3H) as the CF2 sources. The advantage of this reaction is that the (sila)difluoromethylated compounds can be obtained by simple treatment of easily accessible substrates, lithium bases, and CF3TMS or CF3H. Furthermore, the products bearing the TMS group can be transformed into the valuable compounds with the CF2 fragment via the carbon-carbon bond forming reactions.

A class of effective decarboxylative perfluoroalkylating reagents: [(phen)2Cu](O2CRF)

A class of effective reagents [(phen)₂Cu](O₂CR_F) for the decarboxylative perfluoroalkylation of aryl and heteroaryl halides have been invented.