Preparation of new nitrogen-bridged heterocycles. XXIV. Syntheses and reactions of pyrazolo(1,5-a)pyridine-2-thiols. (2).
作者:Akikazu KAKEHI、Suketaka ITO、Tosio SAKURAI、Kunio URUSHIDO、Hidetoshi ISAWA、Tsuneaki TAKASHIMA
DOI:10.1248/cpb.38.2667
日期:——
Various 2-(acylmethylthio)-, 2-(benzylthio)-, and 2-(propargylthio)pyrazolo[1, 5-a]pyridine derivatives (4a-n' and 7a-n') were prepared in moderate to good yields by the reactions of potassium pyrazolo[1, 5-a]pyridine-2-thiolates (2 and 6), readily available by the treatment of 2-[(2-ethoxycarbonylethyl)thio]- and 2-[(2-cyanoethyl)thio]pyrazolo[1, 5-a]pyridines (1a-h and 5a-h) with potassium tert-butoxide in N, N-dimethylformamide (DMF), with alkylating agents such as chloroacetone (3a), phenacyl bromides (3b-d), ethyl bromoacetate (3e), benzyl bromides (3f-k), and propargyl bromide (31). Of these S-functionalied pyrazolo[1, 5-a]pyridines only 2-(acetonylthio)- and 2-(phenacylthio)pyrazolo[1, 5-a]pyridine-3-carbonitriles (4a-t) were converted to new heterocyles, thieno[2', 3' : 3, 4]pyrazolo[1, 5-a]pyridines (8a-t) by heating them with 1, 8-diazabicyclo[5.4.0]undec-7-ene (DBU); the other compounds did not provide any tricyclic heterocycles under various alkaline conditions. The structures of thieno[2', 3' : 3, 4]pyrazolo[1, 5-a]pyridines (8a-t) were determined mainly by elemental analyses and spectral inspections, and the structural assignment was confirmed by the X-ray analysis of compound 8d.
各种 2-(酰基甲硫基)-、2-(苄基硫基)- 和 2-(丙炔基硫基)吡唑并[1, 5-a]吡啶衍生物(4a-n' 和 7a-n')是通过吡唑并[1、5-a]吡啶-2-硫代酸钾盐(2 和 6)的反应制备了吡唑并[1, 5-a]吡啶衍生物(4a-n'和 7a-n')、5-a]吡啶(1a-h 和 5a-h),在 N,N-二甲基甲酰胺(DMF)中用叔丁醇钾和烷化剂(如氯丙酮 (3a)、苯基溴化物 (3b-d)、溴乙酸乙酯 (3e)、溴化苄酯 (3f-k) 和溴化丙炔 (31))进行处理。在这些 S 官能化的吡唑并[1, 5-a]吡啶中,只有 2-(乙酰硫基)- 和 2-(苯乙酰硫基)吡唑并[1, 5-a]吡啶-3-甲腈(4a-t)通过与 1, 8-二氮杂双环[5.4.0]十一碳-7-烯 (DBU)加热;其他化合物在各种碱性条件下没有生成任何三环杂环。主要通过元素分析和光谱检测确定了噻吩并[2', 3' : 3, 4]吡唑并[1, 5-a]吡啶(8a-t)的结构,化合物 8d 的 X 射线分析证实了其结构归属。