Lewis Acid Promoted Annulations Of ?-Butyrolactone Fused Cyclopropanes With Heterocumulenes/Anthranils

In this thesis,Lewis acid promoted annulations of?-butyrolactone fused cyclopropanes with heterocumulenes/anthranils is reported.The[3+2]annulations of?-butyrolactone fused donor–acceptor?D–A?cyclopropanes with aromatic/alkyl isothiocyanates and dialkyl carbodiimides promoted by FeCl₃ is reported.A series of bicyclic/polycyclic?-butyrolactone fused thioimidates and?-butyrolactone fused amidines containing four contiguous stereogenic centers were obtained in excellent yields as single stereoisomers.Under the catalysis of Sc?OTf?₃,the[3+4]annulations of?-butyrolactone fused donor–acceptor?D–A?cyclopropanes with anthranils is reported.This annulation consists of a reaction sequence involving ring-opening/aromatization/nucleophilic addition.Thereinto,aromatization is the driving force for this annulation.Using this reaction,a series of seven-membered N-heterocyclic fused?-butyrolactone can be prepared conveniently with excellent yields and diastereoselectivity.All the products were well characterized by¹H NMR,¹³C NMR,IR and HRMS.The relative configurations of some typical products were determined by COSY,NOESY,HSQC and X-ray crystallographic analysis.