2-Ethynyl-1,3,5-trimethylbenzene → 1,3,4-Tris(2,4,6-trimethylphenyl)-1H-1,2,3-triazolium hexafluorophosphate

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Reaction Steps

To a stirred suspension of triazene 8b (5.63 g, 20 mmol) and mesitylacetylene 9b (5.76 g, 40 mmol) in dry dichloromethane (100 mL) in the dark at −78° C. is added tert-butyl hypochlorite (3.33 mL, 30 mmol), upon which the mixture instantly darkens. The mixture is stirred overnight as it is slowly allowed to warm to room temperature. Volatiles are evaporated under reduced pressure, and the crude solid is redissolved in acetone (50 mL), to which is then added potassium hexafluorophosphate (3.68 g, 20 mmol). The mixture is stirred at room temperature for ca. 1 hour, filtered, and the solid residue is washed with dichloromethane. The collected filtrate is 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 10bb as an off-white solid (10.10 g, 88%). Analytical samples were obtained after recrystallization by vapor diffusion of diethyl ether in an acetonitrile solution of 10bb. 1H-NMR (CD3CN, 300 MHz): δ=8.94 (s, 1H), 7.27 (s, 2H), 7.10 (s, 2H), 7.05 (s, 2H), 2.43 (s, 3H), 2.31 (s, 3H), 2.28 (s, 3H), 2.25 (s, 6H), 2.17 (s, 6H), 2.06 (s, 6H). 13C-NMR (CD3CN, 75 MHz): δ=145.2, 144.5, 144.3, 143.9, 139.6, 135.7, 135.2, 132.4, 131.7, 131.5, 131.3, 131.1, 130.9, 119.0, 21.5, 21.4, 21.3, 19.1, 17.9. HR-MS (ESI): Calcd. for C29H34N3 [M+]: 424.2747. found 424.2758.

Provenance & Evidence