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6-甲基-4-(1H)-吡啶酮-3-羧酸(5)是一种广谱头孢霉素的主要组分。过去从4-羟基-6-甲基-2-吡喃酮出发的两种合成法,收率低,成本高,难以工业化生产。现改进从4-羟基-6-甲基-2(1H)-吡啶酮-3-羧酸乙酯(1)出发,经磷酰氯处理得2,4-二氯-6-甲基吡啶-3-羧酸乙酯(2)。再选择取代4位氯得4-烷氧基吡啶衍生物(3)。然后氢化得4-烷氧基-6-甲基-吡啶-3-羧酸乙酯(4)。随即水解得5。原料易得,总收率均50‰。 2,4-二氯-6-甲基吡啶-3-羧酸乙酯(2): 1(59.2g,0.3mol)与POCl_3(201g,1.3mol)的混合物,在密封管中于140℃加
6-Methyl-4- (1H) -pyridone-3-carboxylic acid (5) is a major component of a broad-spectrum cephalosporin. In the past from the 4-hydroxy-6-methyl-2-pyrone two methods of synthesis, low yield, high cost, difficult industrial production. Starting from 4-hydroxy-6-methyl-2 (1H) -pyridone-3-carboxylic acid ethyl ester (1), treatment with phosphorus oxychloride gave 2,4- dichloro-6-methylpyridin-3 - carboxylate (2). An alternative to 4-chloro-4-alkoxypyridine derivative (3) is also selected. Hydrogenation then gave 4-alkoxy-6-methyl-pyridine-3-carboxylic acid ethyl ester (4). Hydrolysis then 5. Easy to get raw materials, the total yield of 50 ‰. A mixture of ethyl 2,4-dichloro-6-methylpyridine-3-carboxylate (2): 1 (59.2 g, 0.3 mol) and POCI3 (201 g, 1.3 mol)