1,8-Diazabicyclo(5.4.0)undec-7-ene → 6-Methoxy-3-(4-nitro-pyrazol-1-yl)-1-oxa-9-aza-phenanthren-2-one

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Reaction Steps

Sodium hydrogen carbonate (4.96 g, 59.06 mmol, 3.0 eq) is added at room temperature to a stirred solution of (4-nitro-pyrazol-1-yl)-acetic acid (3.77 g, 21.65 mmol, 1.1 eq) and O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (14.97 g, 39.37 mmol, 2.0 eq) in N,N-dimethylformamide (200 mL). After 1 h 30 stirring at room temperature 3-hydroxy-6-methoxy-quinoline-4-carbaldehyde (4.0 g, 19.69 mmol, 1.0 eq) is added and the resulting mixture is stirred at room temperature for 3 hours before the addition of 1,8-diazabicyclo[5,4,0]undec-7-ene (11.8 mL, 78.74 mmol, 4.0 eq). After 48 hours stirring at room temperature, the reaction mixture is poured into water (1000 mL) and the resulting solid is collected by filtration to afford 6-methoxy-3-(4-nitro-pyrazol-1-yl)-1-oxa-9-aza-phenanthren-2-one as a yellow solid (4.0 g, 57% yield).

Provenance & Evidence