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Part-IExperimentalThe mixture of anthranilic acid hydrazide (10.02 gm; 0.05 mole) and diethyl oxalate (19.5gm; 0.133 mole) was heated under reflux with stirring in an oil bath at 180 o C for 6 hrs.The excess of diethyl oxalate was removed under vacuum to give a semi-solid whichbecame crystalline on treatment with ethanol. Recrystallization from methylenedichloride gave 6.8 gm (44%) of colorless crystals of 3-amino-2-carbethoxyquinazolin-4-one (Ixiv) (140-142 o C) 9 .M.P. : 137-139 o C; Yield: 44%Mol. Formula : C 11 H 11 N 3 O 3 ; Mol. Wt. 233.2IR(KBr)cm -1 : 3476, 3334(γ NH ), 2998(γ C-H ), 1739(γ C=O ), 1687(γ CONH ).1 H NMR (CDCl 3 )δppm : 1.45 (3H, t, COOCH 2 CH 3 , J = 7.2), 4.50 (2H, q, COOCH 2 CH 3 ,J = 6.9 & 7.2), 5.15 (2H, s, br, NH 2 ), 7.48-8.29 (4H, m, Ar-H).MS m/e : 233(M + ), 218, 204, 161, 144.15. Synthesis of methyl 3, 4-dimethoxy-6-amino-benzoate 10 (Ixv)a. Synthesis of 3, 4-dimethoxybenzaldehydeThe solution of KOH (30.3 gm in 49.5 ml water) was added dropwise into the meltedvanillin (0.3 mol; 50.0 gm) with constant stirring. Simultaneously, dimethyl sulfate (52.8gm; 0.39 mol) was added dropwise with continuous stirring till addition was complete.The mixture was transferred to porcelin dish and kept overnight, then washed with icecold water and dried in a vacuum dessicator. The product (51.0 gm; 93.4%) melting at 43-44 o C (44 o C) 10 was characterized as 3, 4-dimethoxybenzaldehyde (veratraldehyde).M.P. : 43-45 o C; Yield: 93.4%Mol. Formula : C 9 H 10 O 3 ; Mol. Wt. 166b. Synthesis of 3-4-dimethoxy-6-nitrobenzaldehydeTo the stirred solution of conc. HNO 3 (310 ml) in an ice bath (0-5 o C), powderedveratraldehyde (50.0 gm; 0.3 mole) was added over a period of 45 min. After the additionwas complete, the reaction mixture was allowed to stand at 15 o C for half an hour in darkand then poured on an ice-water mixture (2 lit). The yellow voluminous precipitated solidwas filtered, washed with ice cold water, dried and recrystallized from methanol to yield ayellow crystalline solid product. The product (40.0 gm; 62.6% yield) melting at 132-134 o C (134-136 o C) 10 was characterized as 3-4-dimethoxy,6-nitrobenzaldehyde.173