2,6-Di-tert-butylselenopyran-4-one → 2,6-Di-tert-butyl-4-methylselenopyrylium hexafluorophosphate

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Reaction Steps

2,6-Di-tert-butylselenopyran-4-one, compound E, (27.1 grams, 0.100 mole) was dissolved in 250 mL of dry tetrahydrofuran. To this solution was added 40 mL of a 3.0 M solution of methylmagnesium bromide (0.12 mole) in ether. After addition was complete, the reaction mixture was heated at reflux for 1 h and was cooled to ambient temperature. The reaction mixture was slowly added with stirring to 1 L of a cold solution of 10% hexafluorophosphoric acid. The solid was collected by filtration and the filter cake was washed with water (2×250 mL) and ether (3×250 mL). The crude white solid was recrystallized from acetonitrile-ether to give 28.0 g (76% of theoretical) of 2,6-di-tert-butyl-4-methylselenopyrylium hexafluorophosphate, compound F: Melting point 203-204° C.; 1H NMR (deuteriochloroform) d 8.34 (s, 2 H), 2.83 (s, 3 H), 1.66 (s, 18 H). Anal. Calculated for C14H23Se-PF6: C, 40.50; H, 5.58. Found: C, 40.51; H, 5.35.

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