| 摘要 |
<p>In the present invention there is described a process for preparing 4,5-dihydro-1,2,4-triazin-3(2H)-ones of the general formula III, in which Ri1 represents hydrogen, alkyl containing 1 to 12 carbon atoms, cycloalkyl containing 3 to 6 carbon atoms alkoxyalkyl having 1 to 4 carbon atoms the alkoxy moiety and 1 to 6 carbon atoms in the alkyl moiety, haloalkyl containing 1 to 2 carbon atoms or optionally substituted phenyl, benzyl, phenethyl, phenylpropyl, phenylbutyl or phenylpentyl, Re2 represents hydrogen, alkyl containing 1 to 6 carbon atoms, cycloalkyl containing 3 to 6 carbon atoms or optionally substituted phenyl or Ri1 and Ri2 form together 3- to 7-membered carbocyclic ring, Ri3 represents hydrogen or alkyl containing 1 to 6 carbon atoms and Z represents -N=CH- or -NH-CHi2-. The process is characterized by bringing into reaction aminotriazinone of the general formula IV with nicotine aldehyde and obtained pyridylmethylene aminotriazinone is then optionally transferred by selective reduction to pyridylmethyl aminotriazinone, whereby the nicotine aldehyde is prepared by catalytic reduction of 3-cyanpyridine with hydrogen in the presence of Raney nickel, whereby the Raney nickel is used in an amount ranging from 2 to 10 percent by weight based on the cyanopyridine. As a solvent there is used an aqueous carboxylic acid, pH value of the reaction ranges between 3.5 to 7, reaction temperature is lower than or equal to 40 degC, hydrogen pressure is in the range of 0.02 to 0.5 MPa, the amount of consumed hydrogen is up to 110 percent based on the cyanopyridine and the amount of water is in excess based to the cyanopyridine.</p> |
