| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject substituted pyridine that is useful for treatment of diseases relating to endothelin receptor, particularly the therapy of cardiovascular diseases in high selectivity and high yield by carbamoylation of a substituted pyridine in the presence of a large amount of a ferric salt. SOLUTION: (A) A compound of formula I (R4-R8 are each H, a lower alkoxy, a halogen) or its salt is allowed to react with (B) formamide in (C) an acidic aqueous solution by using (D) 15-40 mol.%, based on the component A, of a ferric salt (an iron salt containing an anion for example, chloride, bromide, sulfate, phosphate or the like) and (E) an oxidizing agent (preferably hydrogen peroxide), preferably at 0-35 deg.C to give a compound of formula II preferably 4-[4,6-dihydroxy-5-(2-methoxy-phenoxy) pyrimidin-2-yl] pyridine-2-carboxylic amide} or its salt. Through this process, an endothelin receptor inhibitor can be prepared in a remarkable yield.
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