Studies On P?NMe₂?₃ Mediated Reductive ?3+2? Annulation Of Benzils With Pyrylium Salts

The redox addition reaction of 1,2-dicarbonyl compounds with trivalent phosphorus derivatives,which is called Kukhtin-Ramirez reaction,providing a simple and effective strategy for carbonyl umpolung.While the Kukhtin-Ramirez adducts(KRAs)derived from ?-ketoesters has been widely used in organic synthesis,the research on the Kukhtin-Ramirez chemistry of ?-diketones are rare due to the low activity of their KRAs.In this thesis,we reported the(3+2)annulation of KRAs derived from benzils with highly electrophilic 2,6-disubstituted pyrylium salts,which provides a facile method for the synthesis of the novel tetrasubstituted furan bearing the cis-chalcones motifs.While KRAs derived from benzils function as a C3 synthon,the pyrylium ions serve as a C2 synthon bearing a Z-enone unit for the first time in this(3+2)annulation.Thus,it deepens our understanding about the classical Kukhtin-Ramirez reaction and broadens its application in organic synthesis.The mild reaction conditions,simple practicity,and the regioselective reductive(3+2)annulations with unsymmetrical benzil derivatives by virtue of the electronic and steric effects of the substituents on benzilsmade the current annulation a promisting synthetic method for tetrasubstituted furan.