Multicomponent Synthesis of 4-Aryl-4,9-dihydro-1H-pyrazolo[3,4-b]quinolines Using L-Proline as a Catalyst—Does It Really Proceed?
作者:Andrzej Danel、Elżbieta Porębska、Kacper Markiel、Oleksii Havrysh、Mateusz Kucharek、Arkadiusz Gut、Tomasz Uchacz
DOI:10.3390/molecules28227612
日期:——
Looking for effective synthetic methods for 1H-pyrazolo[3,4-b]quinolines preparation, we came across a procedure where, in a three-component reaction catalysed by L-proline, 4-aryl-4,9-dihydro-1H-pyrazolo[3,4-b]quinolines are formed. These compounds can be easily oxidised to a fully aromatic system, which gives hope for a synthetic method that could replace, e.g., Friedländer condensation, often used
在寻找制备 1H-吡唑并[3,4-b]喹啉的有效合成方法时,我们发现了一种方法,在 L-脯氨酸催化的三组分反应中,4-芳基-4,9-二氢-1H-形成吡唑并[3,4-b]喹啉。这些化合物可以很容易地氧化成完全芳香族体系,这为替代通常用于此目的的弗里德兰德缩合等合成方法带来了希望,尽管该方法受到合适底物可用性的严重限制。然而,在仔细重复该出版物中描述的程序后,结果发现该出版物中描述的化合物根本不形成。实际的化合物是4,4-(苯基-亚甲基)-双-(3-甲基-1-苯基吡唑-5-烯)。因此,通过另一种方法制备4-芳基-4,9-二氢-1H-吡唑并[3,4-b]喹啉并用作标准品来比较原始过程中形成的产物。