Studies Toward The Synthesis Of Pyrrole(Furan)Derivatives Based On Electron-Deficient Allenes

As important five-membered heterocyclic skeletons,pyrroles and furans widely spread in many natural products,pharmaceutical molecules,organic functional materials,pesticides and other fields.So far,although there are a variety of methods can be used to synthesize pyrroles and furans,the continuous studies for the synthesis of pyrroles and furans in terms of efficient,environmentally sustainability,operational simplicity,and economic viability are still of great significance.This dissertation mainly focuses on the synthesis of pyrroles(furans)from electron-deficient allenes,which includes the following three aspects:1.Iodine-catalyzed construction of polysubstituted pyrroles from electron-deficient al-lenes and enamines.In the first part,a novel I2-catalyzed Michael addition/oxidative annulation of elec-tron-deficient allenes and enamines for the construction of polysubstituted pyrroles with the highest yield of 91%has been developed.This protocol features mild reaction conditions,op-erational simplicity and excellent regioselectivities,providing a novel strategy for the synthe-sis of polysubstituted pyrroles.2.Iodine-catalyzed construction of polysubstituted furans from electron-deficient allenes and ?-keto acid.In the second part,a novel quaternary ammonium salt-mediated Michael addition,and then KI-catalyzed oxidative annulation of electron-deficient allenes and ?-keto acid for the construction of polysubstituted furans has been developed.The reaction features operational simplicity,metal-free reaction,environmental protection,which provides a new way for the synthesis of polysubstituted furans.3.Preliminary studies of iodine-catalyzed construction of polysubstituted benzofurans from electron-deficient allenes and phenols.In the third part,a novel TBAI-catalyzed Michael addition/oxidative annulation of elec-tron-deficient allenes and phenols for the construction of polysubstituted benzofurans has been attempted.This protocol stops in Michael addition with high yield and has no further reaction.Although we have not obtain the desired product,this method also provides a novel idea for the synthesis of polysubstituted benzofurans.