4-ALKOXYCARBONYL, 4-ALKYLTHIOCARBONYL AND 5-ALKOXYCARBONYLOXY DERIVATIVES OF 1-SUBSTITUTED-3-METHYLPYRAZOL-5-ONES

The reaction of 1-substituted-3-methylpyrazol-5-ones 1 with alkyl chlo roformates and calcium hydroxide in dioxane have been studied. With 1- phenyl-3-methylpyrazol-5-one, the isolated product was alkyl 3-methyl- 5-oxo-1-phenylpyrazole-4-carboxylate 2 but with 1-alkyl-3-methylpyrazo l-5-one formation of 1-alkyl-5-alkoxycarbonyloxy-3-methylppazole 3 was observed. Replacement of alkyl chloroformate by bis(alkoxythiocarbony l) sulfide results in the formation of 4-alkoxythiocarbonyl derivative s 4 in low yield with both 1-substituted-3-methylpyrazol-5-ones.