Sc（OTf）₃-catalyzed [3+2] Annulation Of Donor-Acceptor Cyclopropanes With α-EWG Ketene Dithioacetals

Because of its unique construction,α-EWG Ketene Dithioacetals are very important intermediate in organic synthsis.α-EWG Ketene Dithioacetals have many reaction types.Because ofα-C nucleophilicity and β-C-S easy breakage,annulation reaction is very popular research.Heterocyclic compounds like furan and coumarin were gained.D-A cyclopropane is the important substrate.Because of the push-pull radical group,the C-C bond is easily breaked and generate a kind of 1,3-zwitterion intermediate which can happen cycloaddition reaction with polarized olefins and dipoles.In annulation reaction,D-A cyclopropane is also very popular.Base on continuous research of Ketene Dithioacetals and D-A cyclopropane,this paper explore the annulationreaction of Ketene Dithioacetals and D-A cyclopropane by Lewis acid catalysted.The main content includes the following:1、Sc（OTf）₃catalysted the [3+2] annulation reaction of D-A cyclopropane with α-EWG Ketene Dithioacetals as polarized olefins was realized and this is a new method which generate a series of important cyclopentenes with many functional groupsfrom simple substrates.2、The preliminary results include:（1）Different kinds of radical group are tried.When the EWG is acetyl,ester,the reaction is fine.Hydrolysis reaction of α-EWG Ketene Dithioacetals is adverse.（2）The electron supplying capacity of arly is better and D-A cyclopropane is more lively.The ring-opening reaction of cyclopropane with ethanethiolis also adverse.（3）The electronic effect and steric effect of cyclopropane can influence the annulation reaction.3、22 cyclopentenes with many functional groups were characterlized by 13 C NMR、1H NMR、MS spectrum.