Hydrogen Peroxide → Imazaquin

Participants

Reaction Steps

2-Amino-2,3-dimethylbutyronitrile (0.393 mol) is added over 40 minutes to a stirred solution of 2,3-quinolinedicarboxylic anhydride (0.376 mol) in 4-picoline (338 g, 3.63 mol) and toluene (52 g), while maintaining the temperature at 40° to 43° C. The reaction mixture is stirred at 40° to 43° C. for one hour. Aqueous sodium hydroxide (218 g, 25%, 1.36 mol) and then toluene 378 g) are added and the mixture stirred at 55° to 60° C. for approximately 15 minutes. The lower aqueous basic phase is separated off and the product extracted from organic phase with water. The aqueous phase is washed with toluene. A portion of the aqueous phase (25.8 g) is treated with 25% aqueous sodium hydroxide (10 g) and 3.7 equivalents of hydrogen peroxide at 65°-70° C. for one hour, then additional 50% aqueous sodium hydroxide (14.5 g) is added and the reaction mixture is allowed to stir for one hour at 65° to 70° C. The mixture is cooled to 25° to 30° C., and the pH of the mixture adjusted to 1.5 with concentrated sulfuric acid. The product 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-quinolinecarboxylic acid (17.3 g) is isolated by filtration.

Provenance & Evidence