Synthesis Of Indolo[2,1-a]isoquinolines Through Rh(Ⅲ)-Catalyzed Cascade Cyclization Of 2-phenylindoles With 4-hydroxy-2-alkynoates

Indole-containing fused ring compounds are widely present in natural products,pharmaceutical molecules or optically electronic materials.So,their synthesis has attracted the attention of chemists.Traditional constructing this skeleton requires multiple steps and poor regioselectivity.Transition metal-catalyzed C-H activation reaction involving the directing group can effectively solve the regioselectivity,but most of the directing group needs to be removed through an additional step after the reaction is completed.Therefore,utilization of directing group that constitutes the product as a structure fragment in situ could effectively improve the reaction efficiency and atom economy.As for indole,there are multiple reaction sites.Among which,the N-metal bond formed with metal rhodium is more stable than the C-metal bond due to the more electronegative of nitrogen atoms.Thus,the indole could be used as a directing group to participate in the transition metal catalyzed C-H functionalization.4-Hydroxy-2-alkanoates contains ester,hydroxyl and acetylene groups,which can participate in the migration and insertion reaction and the lactonization,and could be used as synthon to build fused rings.In this thesis,based on the properties of indole and4-hydroxy-2-alkanoates,the synthesis of fused indolo[2,1-α]isoquinoline through Rh-catalyzed C-H activation/cyclization reactions of 2-arylindoles and 4-hydroxy-2-alkanoates catalyzed has been developed.The reaction exhibits high efficiency and regioselectivity,tolerates various functional groups,avoids the steps of additional introduction and removal of the directing group,and constructs C-C,C-N,and C-O bonds in one pot,improves the step economy.In addition,the obtained compounds show fluorescent emission,which would provide the potential application in the field of optical electronic materials or molecular recognition.