Sodium hydride → 2,2-Dimethyl-propionic acid 5-bromo-3-(2-methoxy-phenyl)-pyrazolo[3,4,b]pyridine-1-ylmethyl ester

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Reaction Conditions

Reaction Steps

To a solution of 5-bromo-3-(2-methoxy-phenyl)-1H-pyrazolo[3,4-b]pyridine (4.8 g, 15.8 mmol) in DMF (60 ml) at −40° C. under nitrogen, sodium hydride (1.1 g, 47.3 mmol) was added. The mixture was stirred at −40° C. for 1 hour. Then 2,2-dimethyl-propionic acid chloromethyl ester (6.9 ml, 47.3 mmol; chloromethyl pivalate) in DMF (20 ml) was added dropwise and the resulting mixture was allowed to stir at 40° C. for another 2 hours. The reaction was quenched with saturated aqueous NH4Cl (40 ml) and worked up with ethyl acetate, brine, dried with Na2SO4 and evaporated. Silica gel chromatography of the crude using a gradient of ethyl acetate and hexane afforded 2,2-dimethyl-propionic acid 5-bromo-3-(2-methoxy-phenyl)-pyrazolo[3,4,b]pyridine-1-ylmethyl ester (4.1 g, 62% yield). 1H NMR (500 MHz, DMSO-d6) δ 1.11 (s, 9H), 3.85 (s, 3H), 6.46 (s, 2H), 7.09 (m, 1H), 7.24 (d, 1H), 7.51 (m, 1H), 7.60 (d, 1H), 8.43 (s, 1H), 8.74 (s, 1H).

Provenance & Evidence