Studies On The [3+2] Cycloaddition Reactions Of Butatriene And Cyclopropanes With Double Bonds

This thesis was focused on the research of the[3+2]cycloaddition of butatriene with double bonds,the tandem epoxide rearrangement/[3+2]cycloaddition reaction of DA(donor-acceptor)-cyclopropanes with carbonyls,and the tandem Curtius rearrangement/[3+2]cycloaddition reaction of DA-cyclopropanes with isocyanate.Meanwhile the asymmetric total synthesis of ergot alkaloids was also studied.In chapter 1,the research progress of[3+2]cycloaddition reaction was discussed,several aspects of[3+2]cycloaddition reactions such as 1,3-dipolar cycloaddition reactions,the transition metal-catalyzed[3+2]cycloaddition reactions,and the[3+2]cycloaddition of allenes and DA-cyclopropanes were summarized.In chapter 2,based on the summary of the research progress of butatriene,a series of polysubstituted 2,5-dihydrofurans and polysubstituted cyclopentenes with a quaternary carbon center were synthesized by using PBu3-catalyzed[3+2]cycloaddition reactions involving butatriene derivative with aromatic aldehydes or?,?-unsaturated carbonyl substrates.The different regioselectivity was shown in the two types of reactions,and the steric environment of the substrate molecules play a decisive role.For the aromatic aldehydes,the prefer mode of regiochemistry would involve the attack of the a-position of the butatriene to the carbonyl carbon,followed by ring closure.For the ?,?-unsaturated carbonyl substrates,the prefer mode of regiochemistry would involve the y-attack of the butatriene,followed by ring closure.In chapter 3,the methods of building oxygen-bridged complex structures were summarized.A tandem epoxide rearrangement/intramolecular cross[3+2]cycloaddition reaction of cyclopropanes protocol was successfully developed,and a series of spiro-or fused-oxa-[n.2.1]skeletons were constructed under mild conditions.The carbonyls of the[3+2]reaction were produced in situ by the epoxide rearrangement,which could not be easily obtained by common methods.The reaction was applicable for both aliphatic and aromatic epoxide compounds.The reaction showed a single diastereoselectivity which was dictated by the complexing control of Lewis acid and substrates.In chapter 4,the background of building pyrrolo[1,2-a]indole skeleton was described.A tandem Curtius rearrangement/intramolecular parallel[3+2]cycloaddition reaction of cyclopropanes with isocyanate was explored for the efficient construction of pyrrolo[1,2-a]indole skeletons.The isocyanate for the[3+2]cycloaddition was produced in situ by the Curtius rearrangement,which could not been easily obtained by common methods.The[3+2]reaction between cyclopropanes and isocyanate showed a single regioselective.In chapter 5,the chiral propargyl alcohol precursor S-(+)-5-3 was successfully prepared which was used for the asymmetric total synthesis of(+)-cycloclavine,and a chirality transfered aza-Cope-Mannich reaction had been developed.A novel strategy was explored to finish the total synthesis of(+)-cycloclavine.At the same time,the key precursor 5-47 was accomplished to finish the total synthesis of fumigaclavine A.This thesis greatly expanded the scope of the[3+2]cycloaddition reaction,and the different types of cyclic compounds were accomplished successfully which provided potential applications in the synthesis of natural products.The useful exploration has been made for the synthesis of natural products.