Schiff bases derived from tryptophan methyl ester and tryptamine react with Danishefkys diene in the presence of ZnCl2 to give enaminones which are subsequently transformed into indolo[2,3-a]quinolizidin-2-ones by acid-catalyzed cyclization. These tetracyclic aminoketones serve as viable intermediates in the construction of complex alkaloids, e. g. reserpine and deserpidine, and analogues thereof.
Access to Electron-Rich Arene-Fused Hexahydroquinolizinones through a Gold-Catalysis-Initiated Cascade Process
作者:Lianzhu Liu、Liming Zhang
DOI:10.1002/anie.201203303
日期:2012.7.16
Golden Cascade: With a tethered, electron‐rich arene as the internal nucleophile, a gold‐catalyzed amide cyclization to an alkyne initiates a cascadeprocess that ends with a Ferrier rearrangement. Electron‐rich arene‐bearing hexahydroquinolizin‐2‐ones are formed in good yields and can be converted into indole alkaloids in only a few steps.