Cesium carbonate → tert-Butyl 3-(4-amino-3-iodo-1H-pyrazolo[3,4-d]pyrimidin-1-yl)azetane-1-carboxylate

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Reaction Conditions

Reaction Steps

A mixture of 3-iodo-1H-pyrazolo[3,4-d]pyrimidin-4-amine (0.73 g, 0.0028 mol), tert-butyl 3-[(methylsulfonyl)oxy]-1-azetanecarboxylate (1.05 g, 0.0042 mol) and cesium carbonate (1.4 g, 0.0042 mol) in N,N-dimethylformamide (25 mL) were stirred at 70° C. under an atmosphere of nitrogen for 16 hours. The mixture was cooled to room temperature. Additional tert-butyl 3-[(methylsulfonyl)oxy]-1-azetanecarboxylate (0.35 g, 0.0014 mol) and cesium carbonate (0.46 g, 0.0014 mol) were added to the mixture. The mixture was stirred at 70° C. under an atmosphere of nitrogen for 16 hours. The solvent was removed under the reduced pressure. The residue was partitioned between water and ethyl acetate. The aqueous layer was extracted with dichloromethane (3×70 mL). The combined organic extracts were washed with water, and brine, and dried over magnesium sulfate. The solvents were evaporated under the reduced pressure. The residue was triturated with dichloromethane (2×3 mL) to give tert-butyl 3-(4-amino-3-iodo-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-1-azetanecarboxylate (0.57 g, 0.0014 mol). RP-HPLC (Delta Pak C18, 5 μm, 300A, 15 cm; 5%-95% acetonitrile—0.1M ammonium acetate over 10 min, 1 mL/min) Rt 9.4 min. MS: MH+ 417

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