Phenylacetylene → 1,3-Bis(2,6-difluorophenyl)-4-phenyl-1H-1,2,3-triazolium hexafluorophosphate

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Reaction Steps

To a stirred suspension of triazene 8d (808 mg, 3 mmol) and anhydrous potassium hexafluorophosphate (750 mg, 4 mmol) in dry dichloromethafne (20 mL) in the dark at −78° C. is added tert-butyl hypochlorite (500 μL, 4.4 mmol), upon which the mixture instantly darkens. Stirring is pursued at −78° C. for 30 min, and phenylacetylene 9a (660 μL, 6 mmol) is added. The mixture is stirred overnight as it is slowly allowed to warm to room temperature. The contents are then filtered, and the solid residue is washed with dichloromethane. The filtrate is collected, and volatiles are evaporated under reduced pressure. Diethyl ether is then added, and the mixture is vigorously triturated for ca. 1 hour, with occasional scratching of the glass surfaces to ensure efficient mixing. Filtration and washing with copious quantities of diethyl ether afford, after drying under vacuum, triazolium salt 10da as an off-white solid (0.79 g, 51%). Analytical samples were obtained after recrystallization by vapor diffusion of diethyl ether in an chloroform solution of 10da. 1H-NMR (CD3CN, 300 MHz): δ=9.23 (s, 1H), 7.94-7.83 (m, 2H), 7.70-7.66 (m, 1H), 7.63-7.53 (m, 4H), 7.47 (t, J=7.9 Hz, 2H), 7.37 (td, J=8.0, 3.3 Hz, 2H). 13C-NMR (CD3CN, 75 MHz): δ=157.7 (d, J=258 Hz), 157.0 (d, J=257 Hz), 147.3, 137.6 (t, J=10 Hz), 136.9 (t, J=10 Hz), 133.9, 133.1, 130.9, 130.0, 122.1, 114.9 (d, J=21 Hz), 114.7 (d, J=22 Hz), 113.7 (t, J=8 Hz), 111.9 (t, J=8 Hz). 19F-NMR (CD3CN, 282 MHz): δ=−72.0 (d, J=705 Hz, 6F), −117.4 (2F), −119.2 (2F). HR-MS (ESI): Calcd. for C20H12F4N3 [M+]: 370.0962. found 370.0967.

Provenance & Evidence