| 摘要 |
PURPOSE: A process for the preparation of 2,5-disubstituted pyridine is provided to economically obtain the product, 2,5-disubstituted pyridine at a higher yield without taking place of a secondary reaction. CONSTITUTION: The process for the preparation of 2,5-disubstituted pyridine represented by the formula I comprises reacting an enamine of the formula II with beta-amino-acrylonitrile of the formula III at a temperature of -70 to 50 deg.C in liquid phase and in the presence of a C1-C8-carboxylic acid to obtain an open chain intermediate, and then subjecting it to a ring-closure reaction with a protonic acid or an ammonia in a reaction medium composed of a C1-C8-carboxylic acid, a halogenated hydrocarbon, an alcohol, an amide or a mixture thereof. In the formula I-III, R1 is methyl or ethyl, R2 and R3 form a saturated 5-membered heterocyclic ring or 6-membered heterocyclic ring, R4 and R5 form a saturated 5-membered heterocyclic ring, and X is chlorine, bromine or hydroxy.
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