| 摘要 |
PURPOSE: Pyridine derivatives useful as circulatory disturbances therapeutic agent are prepared by high yield. CONSTITUTION: Compound II(R4, R5, R6, R7 and R8 are H, lower alkoxy or halogen), formaldehyde and oxidation agent such as hydrogen peroxide are reacted at 0- 35 degree C in an acid aqueous solution in the presence of 15- 40 mole % of ferric containing anion selected from chloride, bromide, sulfate, phosphate, tetrafluoroborate or hexafluoroborate to give compound I and their salt. Thus, 136 g of 5-(2-methoxy-phenoxy-2-pyridin-4-yl-pyrimidin-4,6-diol, 1,360 ml of formamide are suspended, and added 11.7 ml of conc. sulfuric acid and 365.5 g of ferric sulfate heptahydrate at 0 degree C, followed by addition of 89 ml 30 % hydrogen peroxide at 0- 5 degree C for 1 hour. The reaction solution is stirred at 0 degree C for 1.5 hours, added 83 g of sodium pyrosulfite in 680 ml of deionized water at 0- 5 degree C for 30 minutes to give 132.4 g of 4-£4,6-dihydroxy-5-(2-methoxy-phenoxy)-pyrimidin-2-yl|-pyridine-2-carboxylic amide.
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