2,4(1H,3H)-Quinazolinedione, 7,8-Dimethoxy- synthesis

Yield:-

Reaction Conditions:

with sodium hydroxide;acetic acid in water;

Steps:

1 7,8-Dimethoxyquinazoline-2,4-dione (Xa)

EXAMPLE 1 7,8-Dimethoxyquinazoline-2,4-dione (Xa) Acetic acid (177.4 ml., 3.1 moles) was added to a vigorously stirred suspension of 3,4-dimethoxyanthranilic acid (436.5 g., 2.21 moles) in 10 liters of water. Then 2.24 liters of 20% potassium cyanate (5.53 moles) solution was gradually added and the mixture was stirred for one hour at 40° C. After cooling the reaction mixture to 20° C., 3.54 kg. sodium hydroxide pellets were added maintaining the temperature below 40° C. The reaction mixture was heated to 90° C. for 45 minutes and then slowly cooled in an ice bath. The sodium salt of the product was filtered, resuspended in 6 liters of water, acidified with concentrated hydrochloric acid (370 ml.), cooled and filtered to yield 404 grams (82%) of the product. Recrystallization from dimethylformamide gave colorless crystals, M.P. 314°-6° C. Analysis, Percent Calcd. for C₁₀ H₁₀ N₂ O₄: C, 54.05; H, 4.54; N, 12.61. Found: C, 53.96; H, 4.57; N, 12.63.

References:

US4287341,1981,A