Salts of novel chelatoborate anions: [R F BX(ox)] − (R F = CF 3 , C 2 F 5 ; X = F, OMe; ox = oxalato) and [R F B(OMe)(cat)] − (R F = CF 3 , C 2 F 5 ; cat = catecholato)

Convenient Preparation and Structure Determination of Air- and Moisture-Tolerant Difluoromethylborates

Convenient and reliable synthetic methods for difluoromethylborates have been established. The intermediary generated difluoromethylsilicate species from TMSCF₂ H (TMS=trimethylsilyl) and potassium tert-butoxide were allowed to react with pinBPh (Me₄ C₂ O₂ BPh) in the presence of 18-crown-6 to give the corresponding borate compound [pinB(Ph)CF₂ H]^- K⁺ (18-crown-6) as an air- and moisture-tolerant solid. The unambiguously determined crystal structure of [pinB(Ph)CF₂ H]^- K⁺ (18-crown-6) revealed that the difluoromethylborate unit partially coordinated on the potassium ion. Reaction of [pinB(Ph)CF₂ H]^- K⁺ (18-crown-6) with potassium difluoride (KHF₂ ) in acetic acid enabled substitution of the pinacol unit and phenyl group with fluorides, and gave (difluoromethyl)trifluoroborate [F₃ BCF₂ H]^- K⁺ (18-crown-6) in a good yield. The crystal structure of air- and moisture-tolerant [F₃ BCF₂ H]^- K⁺ (18-crown-6), which would be a promising reagent for synthesis of various difluoromethylboron species, showed a polyrotaxane-like polymeric structure based on the K⋅⋅⋅F interactions between the K⁺ (18-crown-6), CF₂ H, and BF₃ units.

Borazine-CF3- Adducts for Rapid, Room Temperature, and Broad Scope Trifluoromethylation

A fluoroform-derived borazine CF₃^- transfer reagent is used to effect rapid nucleophilic reactions in the absence of additives, within minutes at 25 °C. Inorganic electrophiles spanning seven groups of the periodic table can be trifluoromethylated in high yield, including transition metals used for catalytic trifluoromethylation. Organic electrophiles included (hetero)arenes, enabling C-H and C-X trifluoromethylation reactions. Mechanistic analysis supports a dissociative mechanism for CF₃^- transfer, and cation modification afforded a reagent with enhanced stability.