Study On The Synthesis Of Indole-Fused Ring Compounds From 2-Substituted Indole Derivatives

Indoles have attracted much attention because of their utility in the syntheses of bioactive compounds with an array of pharmaceutical properties since its discovery in1866.Indole-fused rings are high-profile skeletons in a wide range of indole alkaloids with remarkable anticancer and anti-tumor activities.Thus,it is significant to exploit a simplified and efficient method to synthetize such compounds.In this thesis,indole-fused pyridones,indole-fused quinolinones and indole-fused cyclopentanones were selectively synthesized from 2-substituted indoles derivatives.The first part:With the metal iron as catalyst,K₂S₂O₈(potassium persulfate)as oxidant,we selectively synthesized pyrido[2,3-b]indol-4-ones from indole-2-enaminones.Substrates were transformed into pyrido[2,3-b]indol-4-ones through intramolecular C-H activation,in which a carbonyl 1,2-migration was involved.We synthesized 23compounds.The route has the merits of easy access to crude materials,mild reaction conditions and good functional group tolerance.The second part:On the basis of our previous work,indolo[3,2-b]quinolines were synthesized by modifying the substrate,employing the similar reaction conditions.Substrates were transformed into indolo[3,2-b]quinolines through intramolecular indole C3-H and amino N-H coupling.The reaction underwent intramolecular Michael addition and the desired products was generated through protonation followed by oxidative aromatization.The Natural Product Quindolinone was conveniently prepared by this reaction.In part three,we attempted to synthesize indole-fused cyclopentanones from 2-substituted indolyl alkynyl ketone and dimethyl malonate.Further studies are on the way in our laboratory.