反应详情

0.02 moles of 2-amino-4-ethoxycarbonylpyridine and 0.02 moles of ethyl-2-ethylacetacetate are stirred in a mixture of 10 ml. of phosphorous oxychloride and 2 g. of polyphosphoric acid at 120° C. for 2 hours. The reaction mixture is treated with 20 ml. of ethanol at 70° to 80° C., whereupon it is neutralized with a 10% (w/v) aqueous sodium hydroxide solution with ice cooling. The ethanol is evaporated, the residue is extracted with four 25-ml. portions of chloroform and the combined extracts are dried and evaporated. The evaporation residue is triturated with ether to give crystalline 2-methyl-3-ethyl-8-ethoxycarbonyl-4-oxo-4H-pyrido-(1,2-a)pyrimidine, melting at 95° to 96° C. Yield 42%. The product does not give any melting point depression when admixed with the product of Example 17.

1. additionThe reaction mixture is treated with 20 ml
2. customat 70° to 80° C.
3. customThe ethanol is evaporated
4. extractionthe residue is extracted with four 25-ml
5. dry with materialportions of chloroform and the combined extracts are dried
6. customevaporated
7. customThe evaporation residue is triturated with ether