Iodine → 5-(5-(iodomethyl)tetrahydrofuran-2-yl)-1-methyl-4-nitro-1H-pyrazole

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Reaction Steps

To a stirred solution of 1-(1-methyl-4-nitro-1H-pyrazol-5-yl)pent-4-en-1-ol (0.84 g, 3.98 mmol, intermediate 59) in dry THF (25 mL) under nitrogen was added iodine (1.52 g, 5.97 mmol). After stirring for 5 min, Na2CO3 (0.63 g, 5.97 mmol) was added followed by silver triflate (3.07 g, 11.94 mmol) and the dark red solution turned yellow. The mixture was stirred at room temperature for 1 hr, diluted with THF (25 mL) and filtered through celite. The yellow solid was washed with THF/DCM and the filtrate concentrated under reduced pressure. Purification via silica gel chromatography (0-40% EtOAc/DCM) gave 5-(5-(iodomethyl)tetrahydrofuran-2-yl)-1-methyl-4-nitro-1H-pyrazole as a pale yellow gum (640 mg, 48%). 1H NMR (400 MHz, CDCl3) δ 8.03 (s, 1H), 5.91-5.87 (m, 1H), 4.39-4.35 (m, 1H), 4.02 (s, 3H), 3.37-3.30 (m, 2H), 2.69-2.67 (m, 1H), 2.45-2.41 (m, 1H), 2.05-1.89 (m, 2H).

Provenance & Evidence