4-氧代-3（4H）-喹唑啉-5-羧酸的合成

以2-氨基-6-甲基苯甲酸为起始原料，通过合环反应生成两种4-氧代-3(4H)-喹唑啉-5-羧酸衍生物(1a, 1b)， 1a, 1b分别经高锰酸钾氧化合成了4-氧代-3(4H)-喹唑啉-5-羧酸（2a, 2b）,其结构经¹H NMR, ¹³C NMR和MS表征。研究了投料比｛r［n(高锰酸钾) :n(5-甲基-3(4H)-喹唑啉-4-酮)］｝和反应温度等对收率的影响。结果表明：在最佳反应条件（r=7:1,中性高锰酸钾氧化,于90 ℃反应）下合成2总收率可达66%。

Syntheses of 4-Oxo-3 ( 4 H)-Quinazolin-5-Carboxylic Acid

Two different 4-oxo-3(4H)-quinazolin-5-carboxylic acid derivatives (1a, 1b) were synthe-sized by ring-closing reaction of 2-amino-6-methyl-benzoic acid.4-Oxo-3(4H)-5-carboxylic acid(2a, 2b) were synthesized by the oxidation of 1a and 1b with potassium permanganate , respectively.The structures were characterizd by 1 H NMR, 13 C NMR and MS.Effects of the molar ratio{r n( potassium permanganate) :n(5-methyl-3(4H)-4-methyl ketone)]} and reaction temperature on yield of 2 were investigated .The results indicated that the yield of 2 was 66%under the optimum condition ( r=7:1 , neutral potassium permanganate oxidation , reacted at 90 ℃) .