Compound HF@5

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Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Compound HF@3 (30% filling factor, 324 mg, 0.2969 mmol) was placed inside a Schlenk flask fitted with a straight condenser under nitrogen atmosphere. Distilled toluene (32 ml) was added followed by triisopropyl phosphite (1.2 ml). The solution was then refluxed for 24 hours. After this time the mixture was allowed to cool down to room temperature, concentrated under reduced pressure and finally purified by flash column chromatography (eluent: toluene). The fractions containing the spot running with the solvent front were collected and evaporated to afford HF@5 as a black solid (30% filling factor, 264 mg , 84%). ¹H NMR (400 MHz, CDCl₃, δ): 7.78 (t, J = 7.8 Hz, 2H, H-4 of pyridyl), 7.72 (d, J = 7.8 Hz, 2H, H-3 or H-5 of pyridyl), 7.33 (d, J = 7.8 Hz, 2H, H-3 or H-5 of pyridyl), 6.47 (s, 2H, alkenyl), 1.37 (s, 18H, t-butyl), -3.88 (d J = 506 Hz, 0.3H, endohedral HF) ppm. ¹³C NMR: (125 MHz, CDCl₃, δ): 168.89, 164.81, 152.37, 149.73, 145.61, 145.56, 145.33, 144.73, 144.53, 144.42, 144.36, 144.29, 144.2, 144.01, 143.97, 143.82, 143.74, 143.59, 143.33, 142.13, 141.25, 140.65, 140.6, 140.51, 140.15, 138.25, 137.11, 137.02, 136.78, 135.28, 135.02, 130.79, 127.5, 120.79, 117.18, 57.52, 37.77, 30.05 ppm. Note: the signals arising from empty compound 5 are present but not listed. ¹⁹F NMR: (376 MHz, CDCl₃, δ): -220.42 (d, J = 506 Hz) ppm. {¹H}¹⁹F NMR: (376 MHz, CDCl₃, δ): -220.43 (s) ppm. IR: (ν): 2960, 1573, 1447, 906, 811, 732 cm^-1. UV: CH₂Cl₂ λ_max (ε): 263.5 nm (76500), 328.7 nm (29400). MS-ESI: m/z (relative intensity, ion): 1059 (15%, [M+H]⁺, HF@5), 1039 (59%, [M+H]⁺, empty 5), 530 (32%, [M+2H]²⁺, HF@5), 520 (100%, [M+2H]²⁺, empty 5).