The Generation Of Isoquinoline Compunds Via Tandem Reactions

It is well know that the isoquinoline skeleton is the important key structural unit which has been found in many natural products. Isoquinoline compounds are important organic intermediates as well in the total synthesis of natural alkaloids. Additionally, these compounds are widely applied in medicinal chemistry, chemical engineering and other fields. Therefore, much attention has been paid for the synthesis of isoquinoline and its derivatives. In this thesis, we mainly focus on the tandem reactions for the generation of isoquinoline compunds.Firstly, an efficient tandem reaction of2-alkynylbenzaldoxime with imidazole catalyzed by silver triflate is described. In order to activate the isoquinoline N-oxides, the presence of bromotrispyrrolidinophosphonium hexafluorophosphate (PyBroP) is essential for the reaction transformation. The reaction generates1-imidazolylisoquinolines in good yields and proceeds smoothly under mild conditions.Secondly, a novel and efficient pathway for the generation of polyfluoroaryl-fused H-pyrazolo[5,1-α]isoquinolines is disclosed. Polyfluoroarene reacts with N’-(2-alkynylbenzylidene)hydrazide catalyzed by silver triflate in the presence of cesium carbonate, leading to the target product.Finally, an efficient tandem reaction of2-alkynylbenzaldoxime with alkylidenecyclopropane catalyzed by silver triflate under mild condition is developed. This reaction proceeds through6-endo-cyclization,[3+2] cycloaddition and intramolecular rearrangement, leading to benzo-7-azabicyclo[4.2.2]dec-7-en-4-ones in moderate to good yields.