Tandem Reaction For Synthesis Of Multisubstituted Dihydrofurans And Dihydropyrroles Based On Claisen Rearrangement Of Allyl Ether

Multi-substituted 2,3-dihydrofurans and 2,3-dihydropyrroles are two common five-membered heterocyclic skeletons,which are widely used in the synthesis of drug molecules and as critical synthetic precursor of many molecules.Claisen rearrangement of allyl ether is a normal method to form C-C bond.As an atomic economy and environmental-friendly synthetic strategy,multi-step tandem reaction has also been frequently applied in the construction of various molecular frameworks in recent years.In this dissertation,we have developed an organocatalytic hydroalkoxylation/Claisen rearrangement/Michael addition tandem sequence to synthesize the polysubstituted 2,3-dihydrofurans and 2,3-dihydropyrroles in a simple and efficient way.This thesis mainly includes the following three parts:1)First of all,we introduced the applications and syntheses of the 2,3-dihydrofurans and 2,3-dihydropyrroles.And then,we explained the applications of Claisen rearrangement of allyl ether in multi-step tandem reaction.Finally,the research progress of cyanohydrins in the synthesis of cyclic compounds is briefly introduced.2)We developed a tandem reaction of hydroalkoxylation/Claisen rearrangement/intramolecular Michael addition under the catalysis of Lewis base,which used allyl cyanohydrins and activated alkynes as raw materials to synthesize multisubstituted 2,3-dihydrofurans and 2,3-dihydropyrroles.3)We have investigated the enantioselectivity of the intramolecular oxa-Michael addition reaction of 1,3-dicarbonyl compounds obtained from Claisen rearrangement reaction to synthesize 2,3-dihydrofurans by using chiral cinchona-derived catalysts.