Pingping Tang

Silver‐Catalyzed Oxidative Activation of Benzylic CH Bonds for the Synthesis of Difluoromethylated Arenes

A mild and catalytic method to form difluoromethylated arenes through the activation of benzylic C-H bonds has been developed. Utilizing AgNO3 as the catalyst, various arenes with diverse functional groups undergo activation/fluorination of benzylic C-H bonds with commercially available Selectfluor reagent as a source of fluorine in aqueous solution. The reaction is operationally simple and amenable to gram-scale synthesis.

Silver-Mediated Oxidative Aliphatic CH Trifluoromethylthiolation†

The first example of a practical and direct trifluoromethylthiolation reaction of unactivated aliphatic CH bonds employs a silver-based reagent. The reaction is operationally simple, scalable, and proceeds under aqueous conditions in air. Furthermore, its broad scope and good functional-group compatibility were demonstrated by applying this method to the selective trifluoromethylthiolation of natural products and natural-product derivatives.

Total Synthesis of Schilancitrilactones B and C

The first total syntheses of schilancitrilactones B and C have been accomplished in 17 steps (longest linear sequence) from commercially available materials. Key steps include an intramolecular radical cyclization to provide the seven-membered ring, late-stage iodination, and an intermolecular radical addition reaction to complete the total synthesis.

Asymmetric silver-catalysed intermolecular bromotrifluoromethoxylation of alkenes with a new trifluoromethoxylation reagent

Fluorinated organic compounds are becoming increasingly important in pharmaceuticals, agrochemicals and materials science. The introduction of trifluoromethoxy groups into new drugs and agrochemicals has attracted much attention due to their strongly electron-withdrawing nature and high lipophilicity. However, synthesis of trifluoromethoxylated organic molecules is difficult owing to the decomposition of trifluoromethoxide anion and β-fluoride elimination from transition-metal–trifluoromethoxide complexes, and no catalytic enantioselective trifluoromethoxylation reaction has been reported until now. Here, we present an example of an asymmetric silver-catalysed intermolecular bromotrifluoromethoxylation of alkenes with trifluoromethyl arylsulfonate (TFMS) as a new trifluoromethoxylation reagent. Compared to other trifluoromethoxylation reagents, TFMS is easily prepared and thermally stable with good reactivity. In addition, this reaction is operationally simple, scalable and proceeds under mild reaction conditions. Furthermore, broad scope and good functional group compatibility has been demonstrated by application of the method to the bromotrifluoromethoxylation of double bonds in natural products and natural product derivatives. The first example of an asymmetric silver-catalysed intermolecular bromotrifluoromethoxylation of alkenes has been described with trifluoromethyl aryl sulfonate as a new trifluoromethoxylation reagent. This reaction is operationally simple, scalable and proceeds under mild reaction conditions, which can be applied to the late-stage trifluoromethoxylation of complex small molecules.

Hypervalent Iodine(III)-Mediated Oxidative Fluorination of Alkylsilanes by Fluoride Ions.

The first example of a hypervalent iodine(III)-mediated oxidative fluorination of alkylsilanes by fluoride ions without the use of transition metals is demonstrated. This reaction is operationally simple, scalable, and proceeds under mild reaction conditions. Mechanistic studies suggest the involvement of a single-electron transfer resulting from the interaction of an organopentafluorosilicate and aryliodonium difluoride, which were generated in situ from the corresponding alkylsilane and iodosobenzene, respectively, in the presence of fluoride ions.

Direct Dehydroxytrifluoromethoxylation of Alcohols

The first example of a direct dehydroxytrifluoromethoxylation of alcohols has been developed. This method generated an alkyl fluoroformate in situ from alcohols, followed by nucleophilic trifluoromethoxylation with trifluoromethyl arylsulfonate (TFMS) as the trifluoromethoxylation reagent. The reaction is operationally simple and scalable, and it proceeds under mild reaction conditions to provide access to a wide range of trifluoromethyl ethers from alcohols. In addition, this method is suitable for the late-stage trifluoromethoxylation of complex small molecules.

Silver-mediated fluorination of alkyl iodides with TMSCF3 as the fluorinating agent

The first example of a silver-mediated fluorination of alkyl iodides with the Ruppert–Prakash reagent (TMSCF3) as a fluorinating agent has been reported. This reaction is compatible with a variety of functional groups and proceeds under mild reaction conditions. Moreover, we demonstrate that the large surface area of CaF2 dramatically increased the reaction yield.