Efficient Synthesis of Maxonine Analogues from N-Substituted Benzyl-1-formyl-9H-β-carbolines
作者:Samiran Hutait、Subhasish Biswas、Sanjay Batra
DOI:10.1002/ejoc.201200068
日期:2012.4
intermediate, which undergoes attack by the activated arene subunit of the benzyl moiety. On the other hand, the Morita–Baylis–Hillman adducts of 1-formyl-N-substituted benzyl-9H-β-carbolines undergo an efficient P2O5-mediated intramolecular Friedel–Crafts reaction between the secondary hydroxy group and the activated phenyl group of the benzyl subunit to yield fused-β-carbolines. Investigations into the scope
9-取代苄基-1-(二甲氧基甲基)-9H-β-咔啉中C-1处的缩醛基团与N-9处苄基的芳烃单元之间的酸催化Pomeranz-Fritsch型反应提供稠合-β -咔啉可以很容易地氧化以提供 maxonine 型框架。从机制上讲,反应通过质子化醛作为中间体进行,它受到苄基部分的活化芳烃亚基的攻击。另一方面,1-甲酰基-N-取代的苄基-9H-β-咔啉的 Morita-Baylis-Hillman 加合物在二级羟基和活化的苯基之间发生有效的 P2O5 介导的分子内 Friedel-Crafts 反应。苄基亚基产生融合-β-咔啉。对底物范围的调查表明,该方法的成功取决于苯环的活化程度。对于具有较少活化苯基的底物,仅以中等产率分离吲哚并吲哚衍生物。