Ring transformations of 6H-cyclopropa(e)pyrazolo(1,5-a)pyrimidine. III. Synthesis and X-ray crystal structure determination of a 1-pyrazol-3-ylpyrrole-2-carboxylic acid.
作者:TAKUSHI KURIHARA、TSUTOMU TANI、KEIKO NASU、MASATOSHI INOUE、TOSHIMASA ISHIDA
DOI:10.1248/cpb.29.3214
日期:——
Ring transformations and ring expansions of ka-acetyl-5a, 6a-dihydro-6a-ethoxy-carbonyl-6H-cyclopropa [e] pyrazolo [1, 5a] pyrimidines (3, 4 and 5) are described. For example, treatment of 4a with potassium hydroxide in ethanol gave 4-acetyl-1-(4-cyanopyrazol-3-yl)-5-methylpyrrole-2-carboxylic acid (7a), the structure of which was confirmed by X-ray crystal structure determination. On the other hand, it was found that 3a reacted with ethanol, with ethanol in the presence of potassium hydroxide, or with acetic acid to give 7, 8-dihydro-8-ethoxy (or acetoxy)-4H-pyrazolo [1, 5-a] [1, 3] diazepines (17, 11 or 24, respectively) in moderate yields. Furthermore, when aqueous dioxane was used as the reaction medium, 3a was transformed to ethyl 6-pyrazolo [1, 5-a] pyrimidinepyruvate (22), which was found to exist as a mixture of keto and enol tautomers. The mechanism of formation of these products is discussed.
描述了ka-acetyl-5a, 6a-二氢-6a-乙氧基-碳酰基-6H-环丙烷[e]吡嗪[1, 5a]嘧啶(3、4和5)的环转化和环扩展。例如,将4a与氢氧化钾在乙醇中反应得到了4-乙酰基-1-(4-氰基吡嗪-3-基)-5-甲基吡咯-2-羧酸(7a),其结构通过X射线晶体结构测定得到了证实。另一方面,发现3a与乙醇、在氢氧化钾存在下的乙醇或醋酸反应时,分别以中等产率生成了7, 8-二氢-8-乙氧基(或乙酰氧基)-4H-吡嗪[1, 5-a][1, 3]二氮杂烯(分别为17、11或24)。此外,当使用水合二恶烷作为反应介质时,3a转化为乙基6-吡嗪[1, 5-a]嘧啶丙酸酯(22),被发现以酮和烯醇互变异构体的混合物存在。讨论了这些产物形成的机理。