Potassium bis(trimethylsilyl)amide → 5-[2-Benzyloxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethyl-2-(pyridin-2-yl)methyl-2,6-dihydro-7h-pyrazolo[4,3-d]pyrimidin-7-one

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Reaction Steps

Potassium bis(trimethylsilyl)amide (360 mg, 1.81 mmol) was added to a stirred solution of the title compound of Example 1 (200 mg, 0.36 mmol) in benzyl alcohol (5 ml) at 100° C. and the reaction mixture stirred for 14 hours, then allowed to cool. The resulting mixture was partitioned between dichloromethane (10 ml) and brine (10 ml), the phases separated, the aqueous phase extracted with dichloromethane (2×10 ml) and the combined organic solutions dried (Na2SO4) and evaporated under reduced pressure. The residual benzyl alcohol was removed by Kugelrohr distillation, then the crude product purified by column chromatography on silica gel, using dichloromethane: methanol (97.5:2.5) as eluant, to provide the title compound (86 mg, 39%) as a white solid. Found: C, 59.92; H, 5.64; N, 17.60. C31H34N8O4S; 0.40 H2O requires C, 59.87; H, 5.64; N, 18.02%. δ (CDCl3): 1.05 (3H,t), 1.29 (3H,t), 2.41 (2H,q), 2.56 (4H,m), 3.05 (2H,q), 3.15 (4H,m), 5.68 (2H,s) 5.75 (2H,s), 7.10 (1H,d), 7.24 (1H,m), 7.42 (3H,m), 7.52 (2H,m), 7.64 (1H,m), 8.58 (1H,d), 8.65 (1H,s), 9.02 (1H,s), 10.58 (1H,s). LRMS: m/z 615 (M+1)+.

Provenance & Evidence