Ethyl Acetate → 2,2-Dimethyl-propionic acid 8-(4-acetylamino-benzyl)-3-butyl-1-(2-fluoro-5-nitro-benzyl)-2,6-dioxo-1,2,3,6-tetrahydro-purin-7-ylmethyl ester

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Reaktionsschritte

A solution of 2,2-dimethyl-propionic acid 8-(4-acetylamino-benzyl)-3-butyl-2,6-dioxo-1,2,3,6-tetrahydro-purin-7-ylmethyl ester (104 mg, 0.22 mmol) in acetonitrile (2.0 mL) was treated with 1,8-diazabicyclo[5.4.0]undec-7-ene (0.03 mL, 0.24 mmol) and 2-bromomethyl-1-fluoro-4-nitro-benzene (56.6 mg, 0.24 mmol). The resulting solution was heated to 50° C. for 6 h. At this time, another portion of 1,8-diazabicyclo[5.4.0]undec-7-ene (0.03 mL, 0.24 mmol) was added. The reaction was stirred at 25° C. for 18 h. At this time, the reaction was poured into ethyl acetate (200 mL) and was washed with a 1N aqueous hydrochloric acid solution (1×50 mL) and a saturated aqueous sodium chloride solution (1×50 mL). The organics were dried over magnesium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230–400 mesh, 1:1 ethyl acetate/petroleum ether) afforded 2,2-dimethyl-propionic acid 8-(4-acetylamino-benzyl)-3-butyl-1-(2-fluoro-5-nitro-benzyl)-2,6-dioxo-1,2,3,6-tetrahydro-purin-7-ylmethyl ester (45.3 mg, 33%) as a tan solid: FAB-HRMS m/e calcd for C31H35N6O7F (M+H)+ 623.2630, found 623.2631.

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