[CH3:1][N:2]([C:4]([NH:6][C:7]1[S:8][C:9]([CH:12]2[CH2:15][CH2:14][CH2:13]2)=[N:10][N:11]=1)=[O:5])[NH2:3].[CH2:16]=O.[OH-].[K+]>CO>[CH3:1][N:2]1[C:4](=[O:5])[N:6]([C:7]2[S:8][C:9]([CH:12]3[CH2:15][CH2:14][CH2:13]3)=[N:10][N:11]=2)[CH2:16][NH:3]12-Methyl-4-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-semicarbazide (0.1 mole) dissolved in methanol (100 ml) is charged into a glass reaction vessel equipped with a mechanical stirrer and thermometer. Aqueous formaldehyde (0.2 mole; 37% concentration) is then added to the reaction vessel with stirring. Dilute aqueous potassium hydroxide is added to the reaction mixture to adjust the pH to between 7 and 8 and stirring is continued for a period of about 20 minutes resulting in the formation of a solid precipitate. The precipitate is recovered by filtration, is recrystallized and is dried under vacuum to yield the desired product 2-methyl-4-(5-cyclobutyl-1,3,4-thiadiazol-2-yl)-1,2,4-triazolidin-3-one.
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