Difluorocarbene-Induced Ring-Opening Difluoromethylation-Halogenation of Cyclic (Thio)Ethers with TMSCF2X (X=Br,Cl)**

The ring-opening difluoromethylation-halogenation of cyclic (thio)ethers is reported through a simple strategy relying on carbon-chalcogen bond activation with difluorocarbene. The reaction proceeds through in situ protonation of the previously little-known difluoromethylene oxonium or sulfonium ylide intermediate followed by ring-opening with halide ion to afford halogenated acyclic difluoromethyl (thio)ethers that can then be employed for further elaboration. TMSCF₂X (X=Br, Cl) are unique reagents to achieve this synthetic purpose, which serve as both the difluorocarbene source and the halide ion source.     

1-tert-Butyl-1H-tetrazol-5-yl fluoromethyl sulfone (TBTSO2CH2F): a versatile fluoromethylidene synthon and its use in the synthesis of monofluorinated alkenes via Julia–Kocienski olefination

1-tert-Butyl-1H-tetrazol-5-yl fluoromethyl sulfone (TBTSO₂CH₂F) has been developed as a new and efficient fluoromethylidene synthon for the synthesis of both terminal and internal monofluoroalkenes via Julia–Kocienski olefination reaction. The base-mediated reaction between TBTSO₂CH₂F and carbonyl compounds (aldehydes and ketones) provided terminal monofluoroalkenes in good yields with moderate E/Z selectivity. The dominance of E- or Z-fluoroalkenes could be controlled by selection of proper reaction solvent and temperature. TBTSO₂CH₂F reagent was also found to be readily α-alkylated, acylated, and phenylsulfonylated to give corresponding α-functionalized fluorosulfones, which could be used in the synthesis of alkyl-, acyl-, and phenylsulfonyl-substituted internal monofluoroalkenes via Julia–Kocienski olefination reactions.     

Rapid Deoxyfluorination of Alcohols with N-Tosyl-4-chlorobenzenesulfonimidoyl Fluoride (SulfoxFluor) at Room Temperature

The deoxyfluorination of alcohols is a fundamentally important approach to access alkyl fluorides, and thus the development of shelf-stable, easy-to-handle, fluorine-economical, and highly selective deoxyfluorination reagents is highly desired. This work describes the development of a crystalline compound, N-tosyl-4-chlorobenzenesulfonimidoyl fluoride (SulfoxFluor), as a novel deoxyfluorination reagent that possesses all of the aforementioned merits, which is rare in the arena of deoxyfluorination. Endowed by the multi-dimensional modulating ability of the sulfonimidoyl group, SulfoxFluor is superior to 2-pyridinesulfonyl fluoride (PyFluor) in fluorination rate, and is also superior to perfluorobutanesulfonyl fluoride (PBSF) in fluorine-economy. Its reaction with alcohols not only tolerates a wide range of functionalities including the more sterically hindered alcoholic hydroxyl groups, but also exhibits high fluorination/elimination selectivity. Because SulfoxFluor can be easily prepared from inexpensive materials and can be safely handled without special techniques, it promises to serve as a practical deoxyfluorination reagent for the synthesis of various alkyl fluorides.     

Braided Fiber Current Collectors for High-Energy-Density Fiber Lithium-Ion Batteries

Fiber lithium-ion batteries represent a promising power strategy for the rising wearable electronics. However, most fiber current collectors are solid with vastly increased weights of inactive materials and sluggish charge transport, thus resulting in low energy densities which have hindered the development of fiber lithium-ion batteries in the past decade. Here, a braided fiber current collector with multiple channels was prepared by multi-axial winding method to not only increase the mass fraction of active materials, but also to promote ion transport along fiber electrodes. In comparison to typical solid copper wires, the braided fiber current collector hosted 139 % graphite with only 1/3 mass. The fiber graphite anode with braided current collector delivered high specific capacity of 170 mAh g⁻¹ based on the overall electrode weight, which was 2 times higher than that of its counterpart solid copper wire. The resulting fiber battery showed high energy density of 62 Wh kg⁻¹.     

Nucleophilic (phenylsulfinyl)difluoromethylation of carbonyl compounds with difluoromethyl phenyl sulfoxide

We have successfully achieved nucleophilic (phenylsulfinyl)difluoromethylation of both enolizable and non-enolizable aldehydes and ketones by using difluoromethyl phenyl sulfone (1) as the fluoroalkylating agent. Although the chemical yields of the reactions are good to excellent, the observed diastereoselectivity is poor (dr = 1:1.04-2.03). The present synthetic methodology provides a convenient alternative for the preparation of α-(phenylsulfinyl)difluoromethylated carbinols that were previously synthesized via a two-step procedure.     

Pentafluoroethylbenziodoxole (BIX‐C2F5): A Shelf‐Stable Reagent for Pentafluoroethylation of β‐Ketoesters and Arylboronic Acids

An improved method for the preparation of pentafluoroethylating reagent pentafluoroethyl‐substituted benziodoxole (BIX‐C₂F₅) was described. Under mild conditions, BIX‐C₂F₅ was able to react with β‐ketoesters or aryl/heteroaryl boronic acids to generate pentafluoroethylated compounds in good yields.     

Facile synthesis of α-monofluoromethyl alcohols: Nucleophilic monofluoromethylation of aldehydes using TMSCF(SO2Ph)2

α-Fluoromethyl phenyl sulfone derivatives have been extensively employed in various reactions as versatile fluoromethylating reagents. While nucleophilic monofluoromethylations of aldehydes have been achieved using fluoromethyl phenyl sulfone or fluorobis(sulfonyl)methanes, a facile protocol under mild reaction conditions remains an ardently sought goal. We now report a feasible synthetic approach toward β-monofluorinated alcohols using α-trimethylsilyl-α-fluorobis(phenylsulfonyl)methane [TMSCF(SO₂Ph)₂, TFBSM] as a novel monofluoromethylating reagent. Initiated by a catalytic amount of fluoride, the reagent can be readily added to a variety of aldehydes providing the desired products in high yields. Computational and kinetic studies have revealed the exceptional lability of the Si–C bond in TFBSM compared with other fluoromethylsilane counterparts.     

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 CuC₂F₅. Various aryl iodides were pentafluoroethylated with the TMSCF₃‐derived CuC₂F₅. This method represents the first practical and efficient method for pentafluoroethylation of aryl iodides using commercially available TMSCF₃ as a pentafluoroethyl precursor.