Study On Palladium Catalyzed Cyclization Of Allylic Carbonates

Allyl compounds are widely used as highly active substrates with multi-reaction sites for the construction of cyclic compounds,which are abundant in many drug molecules and materials science.To date,dipolar cycloaddition has emerged as one of the most valuable methods for the synthesis of various cyclic compounds.Particularly,palladium-catalyzed dipolar cycloaddition reactions based on allyl structure have rapidly developed as one of the important methods for the construction of cyclic compounds.Taking the development of new reactions and the design of new bidentate phosphine ligands as the core,this dissertation studied the application of allyl carbonates in palladium-catalyzed cycloaddition reactions.In chapter 1,the latest research advances in palladium-catalyzed dipolar cycloaddition reactions were summarized.In chapter 2,a novel[4+3]annulation reaction of vinyl benzoxazinanones and Morita-Baylis-Hillman(MBH)carbonates has been developed by using chemoselectively activated by Pd(PPh3)4 and PPh3,respectively.By optimizing the reaction conditions,we established the transition metal and Lewis base cooperative catalytic system,and then explored the substrate applicability of the reaction,provided a range of vinyl 2,3-dihydro-1H-benzo[b]azepine derivatives in moderate to good yields and diastereoselectivities.Experimental results indicate that both palladium and phosphine play crucial roles in the annulation reactions.In chapter 3,by application of Pd(PPh3)4/PPh3 cooperative catalytic system,we first report the selective intermolecular activation of bimolecular Morita-Baylis-Hillman carbonates,where phosphine species leads to a zwitterionic allylic P-ylide and Pd(PPh3)4 catalyst generates a π-allylpalladium complex-based 1,3-dipole.A series of bicyclo[3.1.0]hexene products were obtained in good yield and excellent diastereoselectivity by sequential[2+3]/[2+1]cyclization of two highly reactive zwitterionic intermediates.Finally,the cooperative catalytic mechanism of the reaction was explored through further mechanism verification experiments.In chapter 4,a novel P-stereogenic bidentate phosphine ligand was combined with 1-phosphanorbornene and a chiral amine,which was applied to the asymmetric palladium-catalyzed[4+2]cyclization of allyl carbonates and alkylidene pyrazolone.Some attempts were made to optimize the reaction conditions,and a series of novel spiropyrazolones were delivered in reasonable yields,diastereoselectivities,and eneantioselectivities(up to>83%yield,>20:1 dr and up to 96%ee).Subsequently,two diastereoisomers of the chiral spiropyrazolone derivatives were obtained in the presence of palladium and chiral P,N ligand with up to 92%yield and 98%enantioselectivity.An unprecedented ligand-controlled Pd-catalyzed diastereodivergent intermolecular[4+2]cycloaddition reaction was first developed,provided a range of chiral spiropyrazolones.