Allyl bromide → 1,3-Bis(2,4,6-trimethylphenyl)-4-methyl-1H-1,2,3-triazolium hexafluorophosphate

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Reaction Steps

To a stirred suspension of triazene 8b (1.70 g, 6 mmol) and anhydrous potassium hexafluorophosphate (1.10 g, 6 mmol) and allyl bromide 12 (1.04 mL, 12 mmol) in dry dichloromethane (20 mL) in the dark at −78° C. is added tert-butyl hypochlorite (1.0 mL, 9 mmol), upon which the mixture instantly darkens. 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 affords the crude dihydrotriazolium salt 13 as a beige solid (3.02 g, ˜92%), which is contaminated by ca. 30% of the aromatized triazolium salt 10bi. 1H-NMR (CDCl3, 300 MHz): δ=7.07 (s, 2H), 7.06 (s, 2H), 6.03 (t, J=12.7 Hz), 5.20 (t, J=14.9 Hz, 1H), 4.85 (t, J=12.5 Hz, 1H), 3.91 (dd, J=12.8, 2.5 Hz, 1H), 3.68 (d, J=12.6 Hz, 1H), 2.45-2.36 (m, 18H). 13C-NMR (CDCl3, 75 MHz): δ=142.8, 142.6, 135.9, 134.8, 134.3, 134.1, 132.2, 131.2, 130.5, 128.8, 68.3, 59.1, 30.1, 21.3, 21.2, 19.0, 18.7, 17.8. Calcd. for C21H27BrN3 [M+]: 400.1383. found 400.1400.

Provenance & Evidence