Methyl iodide → 3-Ethyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-(2-(R)-methoxy-1-(R)-methyl propoxy)pyridin-3-yl]-2-methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one

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Reaction Steps

(R,R)-2,3 butanediol (7.78 ml, 85 mmol) was added dropwise to an ice-cold solution of sodium hydride (3.74 g, 60% dispersion in mineral oil, 93.5 mmol) in ether (800 ml), and the solution stirred at room temperature for 30 minutes. Methyl iodide (5.6 ml, 89.3 mmol) was added dropwise and the reaction stirred under reflux for 48 hours. 1,3-Dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (10.24 ml, 85 mmol) was added and stirring continued for a further 90 minutes under reflux. The cooled reaction was washed with aqueous ammonium chloride solution (500 ml), dried (MgSO4) and evaporated under reduced pressure. The residual oil was purified by column chromatography on silica gel using an elution gradient of ether:pentane (10:90 to 50:50) to give a pale yellow oil. The title compound of Example 78 (100 mg, 0.2 mmol) and potassium bis(trimethylsilyl)amide (121 mg, 0.61 mmol) in the intermediate alcohol (1 ml), was heated at 110° C. for 30 hours, then the reaction cooled and concentrated under reduced pressure. The residual brown solid was purified by column chromatography on silica gel using diethylamine:ethyl acetate (5:95) as eluant, and repeated using methanol:ethyl acetate (5:95) as eluant. The product was triturated with ether to afford the title compound (7 mg, 6%) as a white solid.

Provenance & Evidence