A versatile synthesis of pyrazolo[3,4-c]isoquinoline derivatives by reaction of 4-aryl-5-aminopyrazoles with aryl/heteroaryl aldehydes: the effect of the heterocycle on the reaction pathways
作者:Sergei L. Bogza、Konstantin I. Kobrakov、Anna A. Malienko、Igor F. Perepichka、Sergei Yu. Sujkov、Martin R. Bryce、Svetlana B. Lyubchik、Andrei S. Batsanov、Natalya M. Bogdan
DOI:10.1039/b417002d
日期:——
has been studied. The initial azomethine derivatives 8 undergo cyclization similar to the Pictet-Spengler condensation to form the intermediate 4,5-dihydroisoquinolines 9 which readily dehydrogenate giving 5-aryl(heteroaryl)-pyrazolo[3,4-c]isoquinoline derivatives 10 as the final products. Whereas for benzaldehyde and its derivatives this one-pot synthesis presents a convenient general route to 5-aryl-pyrazolo[3
研究了4-(3,4-二甲氧基苯基)-5-氨基吡唑7A-D与芳族和杂环醛在强酸性介质(三氟乙酸或甲酸)中的反应。初始的偶氮甲碱衍生物8类似于Pictet-Spengler缩合反应进行环化反应,形成中间体4,5-二氢异喹啉9,该中间体易于脱氢,得到5-芳基(杂芳基)-吡唑并[3,4-c]异喹啉衍生物10作为最终产物。 。而对于苯甲醛及其衍生物,这种一锅合成法则提供了一条通向5-芳基-吡唑并[3,4-c]异喹啉10的简便方法,而在杂环醛的情况下,产物结构随所用醛的结构而显着变化。 :(i)3-吡啶基-,3-喹啉基-,3-噻吩基-和1,2,3-噻二唑基-5-羧醛产生5-杂芳基吡唑并[3,4-c]异喹啉;(ii)1-甲基苯并咪唑基-2-甲醛仅产生不环化的中间体偶氮甲碱8Dh;(iii)1-R-3-吲哚基甲醛(R = H,CH3,CH2Ph)消除杂芳基片段,产生5-未取代的吡唑并[3,4-c]异喹啉11。噻吩-2-甲醛通过两种途径反应(i