1-[Bis(trifluoromethanesulfonyl)methyl]-2,3,4,5,6-pentafluorobenzene

Abstract

[405074-81-9] C9HF11O4S2 (MW 446.21) InChI = 1S/C9HF11O4S2/c10-2-1(3(11)5(13)6(14)4(2)12)7(25(21,22)8(15,16)17)26(23,24)9(18,19)20/h7H InChIKey = RLLDXJXYMKTGPV-UHFFFAOYSA-N (an acid catalyst for organic transformations; an acid activator for chiral Lewis acid catalysts; a precursor for metal catalysts; a sterically bulky counter anion; a nucleophilically weak counter anion) Physical Data: mp 86–87 °C; IR (KBr) 1522, 1501, 1347, 1321, 1198, 1127, 1024, 988, 613 cm−1; 1H NMR (300 MHz, CDCl3) δ 6.21(br s, 1H); 13C NMR (125 MHz, CDCl3) δ 70.4, 98.0, 119.2 (q, 2C, JCF = 330 Hz), 137.8 (d, 1C, JCF = 258 Hz), 138.6 (d, 1C, JCF = 257 Hz), 144.7 (d, 1C, JCF = 264 Hz), 145.4 (d, 1C, JCF = 262 Hz), 147.2 (d, 1C, JCF = 262 Hz); 19F NMR (282 MHz, CDCl3) δ −157.9 (dt, 1F, J = 6.2, 21.5 Hz), −156.8 (dt, 1F, J = 6.2, 21.5 Hz), −142.6 (tt, 1F, J = 5.9, 21.5 Hz), −140.3 (br, 1F), −127.7 (ddd, 1F, J = 5.9, 15.2, 21.5 Hz), −75.2 (s, 6F). Solubility: soluble in most organic solvents such as alcohols, acetonitrile, and dichloromethane. Form Supplied in: white solid. Preparative Method: To a solution of pentafluorobenzyl bromide (0.5 mmol) in dry Et2O (3 mL) was added tert-BuLi (0.34 mL, 0.55 mmol, 1.6 M solution in hexane) dropwise at −78 °C, and the resulting mixture was stirred for 20 min. Triflic anhydride (92 μL, 0.55 mmol) was then added, and the resulting mixture was allowed to warm to room temperature over a period of 1 h. After the reaction mixture was cooled to −78 °C, tert-BuLi (0.34 mL, 0.55 mmol, 1.6 M solution in hexane) was added dropwise, and the resulting mixture was stirred for 20 min. Triflic anhydride (0.55 mmol) was then added, and the resulting mixture was allowed to reach room temperature over a period of 1 h before the reaction was quenched with water. The resultant mixture was neutralized and washed with hexane. The aqueous phase was acidified with 4 M aqueous HCl and extracted with ether twice. The organic layers were dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was subjected to bulb-to-bulb distillation. Purification: recrystallization from hexane-AcOEt. Handling, Storage, and Precautions: this compound is a stable solid in air, but is highly absorbent. Use of gloves and protective clothing is recommended.