Sulfuric Acid → HCID 86732834, compound

Participants

Reaction Conditions

Reaction Steps

1-Cyclopropyl-6,7-dimethoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (Example 50b) (20 g, 69.1 mmol) was dissolved in sulfuric acid (44.2 ml, 830 mmol) with stirring. The thick dark solution was cooled to 0° C. and potassium nitrate (10.48 g, 104 mmol) was added in small portions, while the temperature was maintained below 10° C. by use of an ice-water bath. After the addition, the mixture was kept under 10° C. for 1 h, and then was allowed to warm up to r.t. and stirred overnight. LCMS showed completion of reaction. The mixture was poured into ice-water (300 mL). A yellow solid precipitated out and was collected by filtration, washed with water and ethanol, and dried in vacuo to afford 1-cyclopropyl-6,7-dimethoxy-5-nitro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (14 g, 41.9 mmol, 60.6% yield) as a pale yellow solid. LCMS: [M+H]+: 335.1.

Provenance & Evidence