Transition Metals Promoted Oxidative Addition Reactions Of 1,3-Dicarbonyl Compounds With Aryl-Substituted Allyl Alcohols And 8-Hydroxyisochromanes

"Polysubstituted dihydrofurans"and"multi-stereocentric tricyclic chromane nucleus"structural units are core skeletons widely found in numerous biologically important natural products and drug molecules.Functional molecules derived from these two structural cores have shown a variety of biological activities,such as anti-tumor,anti-oxidation,antidiabetic,anti-inflammatory and cytotoxic activities.Therefore,it is of great significance to develop novel and efficient synthesis methods of these two core skeletons for the research of natural and bionic drugs.Based on our previous works focused on the efficient construction of carbon-carbon bond and syntheses of bioactive natural products,here,we achieved the Mn-catalyzed oxidative addition reactions of 1,3-dicarbonyl compounds with aryl-substituted allyl alcohols and Cu-catalyzed cross-dehydrogenation coupling?CDC?reaction of 1,3-dicarbonyl compounds with 8-hydroxyisochromanes.In particular,there are two parts in this thesis:Part I:1,3-dicarbonyl compounds are often used as highly active and versatile reaction modules to construct various carbocyclic and heterocyclic compounds in organic synthesis.In this chapter,according to the different oxidation systems,the study of oxidative addition reactions between 1,3-dicarbonyl compounds and olefins for the preparation of polysubstituted dihydrofurans was reviewed.What's more,we have successfully developed a novel and versatile tandem S_N2‘nucleophilic substitution/oxidative radical cyclization reaction mediated by Mn?OAc?₃·2H₂O for the synthesis of polysubstituted dihydrofurans by using aryl substituted allylic alcohols and 1,3-dicarbonyl compounds.The use of hexafluoroisopropanol as a solvent can significantly improve the yield of the radical reactions and obviated the laborious separation process.Part II:Direct functionalization through the inactive?-C?sp³?-H bond of ethers by cross-dehydrogenation coupling?CDC?reactions has become an effective method for the synthesis of?-substituted ethers.In this chapter,the study of CDC reactions was reviewed.Up to now,there has been few reports on the methods for directly and efficiently constructing the tricyclic chromophores.Therefore,we achieved a novel copper-catalyzed highly diastereoselective cross-dehydrogenative coupling reaction of1,3-dicarbonyl compounds and 8-hydroxyisochromanes by use of T⁺BF₄^-as oxidant,affording tricyclic chromane products with continuous stereocenters in moderate to high yields.Additionally,in the continuation of further application of our newly developed spiro-pyrrolidine?SPD?catalysts,we used the new chiral spirocyclic pyrrolidine oxazoline ligands and copper salts as catalysts to promote this asymmetric CDC/cyclization reaction and achieved good enantioselectivity?up to 80%ee?,which laid the foundations for the further research.