Metamitron, 4-amino-3-methyl-6-phenyl-l,2,4-triazin-5-one, a kind of herbicide was synthesized from phenylglyoxylic acid ester by three step reactions such as condensation, hydrazinolysis and cyclization. The yield is 48.4%.

• 本文仿制专利的路线，以苯乙酮酸酯为原料，经缩合、肼解及合环三步反应合成了除草剂苯嗪草酮，并且对专利的部分方法进行了改进，使产率从30%25提高为48.；4%25。