Preparation of new nitrogen-bridged heterocycles. XXIII. Syntheses and reactions of pyrazolo(1,5-a)pyridine-2-thiols. (1).
作者:Akikazu KAKEHI、Suketaka ITO、Hidetoshi ISAWA、Tsuneaki TAKASHIMA
DOI:10.1248/cpb.38.2662
日期:——
Some pyridinium 1-[[(2-substituted ethy)thio]thiocarbonyl]aminides (4a-h) were prepared in moderate yields by the reactions of N-unsubstituted pyridinium aminides (2a-e) with carbon disulfide and ethyl acrylate (3a) or acrylonitrile (3b). The S-alkylations of these aminides 4a-h with bromoacetonitrile (5a) or ethyl bromoacetate (5b) at room temperature and the subsequent treatment of the resulting pyridinium salts with 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU) and then with chloranil at 0°C gave the corresponding 2-[(2-substituted ethyl)thio]pyrazolo[1, 5-a]pyridine derivatives (6a-p) in 40-75% yields. The β-eliminations of the 2-substituents in these pyrazolo[1, 5-a]pyridines 6a-p with potassium tert-butoxide in N, N-dimethylfomamide (DMF) proceeded smoothly to provide the title compounds, pyrazolo[1, 5-a]pyridine-2-thiols (7a-j), in good yields along with the release of 3a, b.
通过 N-未取代的吡啶鎓酰胺(2a-e)与二硫化碳和丙烯酸乙酯(3a)或丙烯腈(3b)的反应,以中等产率制备了一些 1-[[(2-取代乙基)硫]硫代羰基]吡啶鎓酰胺(4a-h)。在室温下,这些酰胺 4a-h 与溴乙腈(5a)或溴乙酸乙酯(5b)发生 S-烷基化反应,然后用 1, 8-二氮杂双环[5.4.0]undec-7-ene (DBU) 处理,然后在 0°C 下用氯苯胺处理,得到相应的 2-[(2-取代乙基)硫代]吡唑并[1, 5-a]吡啶衍生物 (6a-p),收率为 40-75%。在 N,N-二甲基甲酰胺(DMF)中用叔丁醇钾对这些吡唑并[1,5-a]吡啶 6a-p 中的 2-取代基进行β-消除,顺利地得到了标题化合物吡唑并[1,5-a]吡啶-2-硫醇(7a-j),收率很高,同时还释放出了 3a,b。