Sodium hydride → 5-bromo-3-iodo-1-(2-methoxy-ethoxymethyl)-1H-pyrazolo[3,4-b]pyridine

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Reaction Steps

To a solution of 5-bromo-3-iodo-1H-pyrazolo[3,4-b]pyridine (470 mg, 1.45 mmol), 60% sodium hydride in mineral oil (104 mg, 4.35 mmol) and tetra-n-butylammonium iodide (134 mg, 0.36 mmol) in DMF (10 mL) was added methoxyethoxymethyl chloride (248 μl, 2.18 mmol) at room temperature and the mixture was stirred for 4 h at the same temperature and subsequently quenched by addition of methanol. The mixture was then distributed between ether and brine and the organic layer dried over sodium sulfate, filtered and concentrated. The crude product was purified by flash silica gel chromatography using a gradient of ethyl acetate in hexanes to afford 5-bromo-3-iodo-1-(2-methoxy-ethoxymethyl)-1H-pyrazolo[3,4-b]pyridine (254 mg, 0.69 mmol, 74% yield) as a colorless solid (1:1 mixture with regioisomer 5-bromo-3-iodo-2-(2-methoxy-ethoxymethyl)-1H-pyrazolo[3,4-b]pyridine). 1H-NMR (500 MHz, d6-DMSO) isomer A (50%) δ8.75 (d, 1H), 8.29 (d, 1H), 5.78 (s, 1H), 3.61-3.63 (m, 2H), 3.37-3.39 (m, 2H), 3.17 (s, 3H); isomer B (50%) δ 8.74 (d, 1H), 8.28 (d, 1H), 5.77 (s, 1H), 3.61-3.63 (m, 2H), 3.37-3.39 (m, 2H), 3.16 (s, 3H).

Provenance & Evidence