3-(Dimethylamino)propenoate-based Regioselective Synthesis of 1,4-Disubstituted 5-Hydroxy-1H-pyrazoles
作者:Jurij Svete、David Kralj、Jasmin Mecinovic、David Bevk、Uros Groselj、Branko Stanovnik
DOI:10.3987/com-06-10682
日期:——
1,4-Disubstituted 5-hydroxy-1H-pyrazoles (9), (12), and (13) were prepared in two steps from hydrazines (2a-k) and 3-(dimethylamino)propenoates (1), (4), and (5). First, acid-catalyzed treatment of enaminones (1), (4), and (5) with (hetero)arylhydrazines (2a-k) afforded the corresponding dimethylamine substitution products, hydrazones (3') and enehydrazines (6) and (7). Under acidic conditions, intermediates
1,4-二取代的 5-羟基-1H-吡唑 (9)、(12) 和 (13) 由肼 (2a-k) 和 3-(二甲基氨基)丙烯酸酯 (1)、(4) 分两步制备, 和 (5)。首先,用(杂)芳基肼(2a-k)对烯胺酮(1)、(4)和(5)进行酸催化处理,得到相应的二甲胺取代产物,腙(3')和烯肼(6)和(7) )。在酸性条件下,中间体 (3')、(6) 和 (7) 不会环化成吡唑衍生物。然而,在甲醇和三乙胺的混合物中加热 3'、6 和 7 以 65-98% 的产率提供了所需的产物。