Hydrochloric Acid → 4-(3-Cyclohexyl-1-methyl-4-oxo-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-6-yl)-3-methoxybenzenesulfonyl chloride

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Reaction Steps

To a 2.5 ml concentrated hydrochloric acid/8.5 ml acetic acid mixed solution of 750 mg (2.12 mmol) of the compound obtained in Example 44, a solution of 220 mg (3.2 mmol) of sodium nitrite in 1.5 ml of water was added with ice cooling. The mixture was stirred for 30 minutes at the same temperature. To the resulting solution, 87 mg (0.65 mmol) of copper dichloride and 4.5 ml of a 22% acetic acid solution of sulfur dioxide were added, and the mixture was stirred at room temperature for 6 hours. Then, water was added to the reaction mixture, and precipitated solids were collected by filtration. The collected solids were dissolved in dichloromethane again, and the solution was washed with water and a saturated aqueous solution of sodium chloride. The washed solution was dried over anhydrous sodium sulfate, and then the solvent was distilled off under reduced pressure. Ether was added to the residue, and the cake was collected by filtration to obtain 673 mg (73%) of the captioned compound.

Provenance & Evidence