Synthesis Of Cyclopenta[b]indole Derivatives Via An Intramolecular Cascade Cyclization Of In Situ Formed Allylic Iminum Ions

This paper studied the synthesis of cyclopenta[b]indole derivatives via an intramolecular cascade cyclization of in situ formed allylic iminum ions.The paper mainly includes two chapters:Chapter I:?1?A brief description of the application of cyclopenta[b]indole derivatives;?2?summarizing the methods for constructing cyclopenta[b]indole derivatives.The construction of indole and its related frameworks have always been a hot topic in the field of organic synthesis.These special heterocyclic structures are widely found in many natural products and pharmaceutical compounds with biological activity.It also has many special properties and broad application prospects in many fields,such as materials science and biochemistry.Accordingly,their synthesis has attracted wide interest and attention of chemists,and many synthetic methods have been successfully developed.However,the methodologies for the synthesis of cyclopenta[b]indole derivatives are very limited.Therefore,development of a facile,green and atomically economical method for the synthesis of these derivatives will be of great significance.Chapter II:Synthesis of cyclopenta[b]indole derivatives via an intramolecular cascade cyclization of in situ formed allylic iminum ions.The research ideas of this project and the method for synthesis of cyclopentan[b]indole derivatives by intramolecular cyclization reaction are introduced firstly.In the experimental part,the indole substituted acrylaldehyde was used as model substrate and anhydrous FeCl₃was used as the catalyst to synthesize the cyclopenta[b]indole derivatives,via an intramolecular aza-Friedel-Crafts reaction.After extensive screening,the optimal reaction conditions were obtained:anhydrous FeCl₃?20 mol%?,morpholine as the solvent,microwave power 300 W,microwave temperature 140°C.Under this optimal condition,the expected product was isolated in 93%yield.Subsequently,the substrate scope of the indole substituted acrylaldehyde was investigated,a series of target products can be synthesized with good to excellent yields under the established reaction conditions.The structures of these products were identified by NMR and high-resolution mass spectrometry.