Synthesis Of Heterocyclic And Acetal Compounds Via Tandem Reactions Based On Carbon-halogen Bond Cross Coupling

The cross couplings of carbon-halogen bond of fundamental tools for the contruction of C-C and C-heteroatom bonds,they play indispensable roles in laboratory research and the areas of chemical and pharmaceutical industries.The researches included in this thesis deals with the designation of tandem reactions wherein the C-halogen coupling is employed as key transformation to combine other chemical transformations.These reactions are used for the synthesis of different organic heterocycles and acetals.Four different sections of reaserch work are included.First,thesyntheticmethodtoward2,3-dihydrobenzoxazinonesvia copper-catalyzed aryl C-halogen bond hydroxylation has been inverstigated.By utilizing o-halobenzamides,dichloromethane(DCM)and hydroxide base as starting materials,the tandem C-halogen bond hdyroxylation and DCM-based double nucleophilic substitution annulation have been furnished via copper catalysis and ligand assistance,which provide a series of 2,3-dihydrobenzoxazinone products.Second,the copper-catalyzed three-component reactions of phosphorus ylides,acyl chlorides and o-halobenzoic acids for the synthesis of isocoumarins have been studied.Using phosphorus ylide and acyl chloride as precursors enables the formation of allene intermediate,this intermediate reactions with o-halobenzoic acid to provide isocoumarins by undergoing oxa-Michael addition and C-C coupling.This method avoids the isolation of unstable allene,and allows the construction of target products via the formation of one C(sp~2)-C bond,one C(sp~2)-O bond and one C=C double bond with simple and efficient fashion.Subseqently,we explored the palladium-catalzyed homo-coupling tandem reactions of o-halobenzamides under microwave irradiation.In the presence of a base and microwave irradiation,two molecules of o-halobenzamides undergo intermolecular reductive coupling and the amide decarbonylative annulation to provide phenanthridinones.The work of this section provides rapid and simple new route to these heterocyclic compounds.Finally,we have investigated the three-component reactions of o-iodophenols,phenyl boronic acids and DCM by combining the Suzuki coupling of aryl C-halogen bond and Williamson etherification.By means of systematical optimization on reaction conditions,the tandem Suzuki coupling and DCM-based double etherification between the three components have been accomplished to yield symmetrical bis-biaryloxyl methanes(acetals),which discloses new synthetic application of Suzuki coupling.