Novel Rearrangement of Pyrazole N-Imines with Acetic Anhydride

概要

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2-Amino-1,3-dimethylindazolium mesitylenesulfonate (I) was allowed to react with a large excess of acetic anhydride in the presence of anhydrous sodium acetate to give the unexpected rearrangement products, 3-acetoxymethyl-1-methylindazole (IV), 3-acetylaminomethyl-1-methylindazole (V) and the deaminated product, 1,3-dimethylindazole (II), and the desired product, pyrazolo [2,3-b] indazole derivative (III), could not be obtained. Likewise, the same reactions of 2-amino-1,3,5-trimethylpyrazolium mesitylenesulfonate (VII) and 2-amino-1,3,4,5-tetramethylpyrazolium mesitylenesulfonate (VIII) gave the rearrangement products, 5-acetoxymethyl-1,3-dimethylpyrazole (IX) and 5-acetoxymethyl-1,3,4-trimethylpyrazole (X), respectively. This is the first example of a rearrangement reaction of aromatic amine N-imine with acid anhydride. The desired product (III) was obtained by the reaction of 2-amino-1-methylindazolium mesitylenesulfonate (XIV) with acetylacetone in the presence of triethylamine, followed by oxidation with lead tetraacetate.
社団法人日本薬学会の論文
1976-09-25