The individual reactions of acetyl group rearrangement are examined to elucidate the complicated formation of five acetylated products of 3-methylpyrazol-5-one (I). In heated acetic acid-anhydride mixture the initially formed 2-acetyl-3-hydroxy-5-methylpyrazole (II) reacts further to produce 1-acetyl-3-hydroxy-5-methylpyrazole (III), 3-acetoxy-2-acetyl-5-methylpyrazole (IV) and finally 3-acetoxy-1-acetyl-5-methylpyrazole (V), while inter- as well as intra-molecular acetyl transfer reaction takes place. The diacetate (V) is a sort of activated ester and is proved to be effective as a mild acetylating reagent of primary and secondary amines.
对乙酰基重排的个别反应进行了研究,以阐明
3-甲基吡唑-5-酮(I)形成五种乙酰化产物的复杂过程。在加热的
乙酸-
乙酸酐混合物中,最初形成的2-乙酰基-3-羟基-5-甲基
吡唑(II)进一步反应,生成1-乙酰基-3-羟基-5-甲基
吡唑(III)、3-
乙酸氧基-2-乙酰基-5-甲基
吡唑(IV),最终形成3-
乙酸氧基-1-乙酰基-5-甲基
吡唑(V),同时发生了分子间和分子内的乙酰基转移反应。二
乙酸酯(V)是一种活性酯,被证明对一级和二级胺具有有效的温和乙酰化试剂作用。