Studies On Palladium-catalyzed Carbonvlative Synthesis Of Heterocycles With Formic Acid As CO Source

In recent years,carbonylation reaction has occupied an important position in organic synthesis,it enables the easy insertion of CO to parent molecule for the construction of a variety of carbonyl-containing compounds.Carbonylation reaction has a widely application in various fields for their good reaction selectivity and friendly environmental effect,which meets the requirements and goals of green chemistry.Heterocycles,due to their diverse biological activities and important medicinal functions,have continuously attracted much attention from researchers in various fields,and a lot of synthetic methods have also been explored.However,most of the synthetic methods for heterocycles still have some disadvantages,such as cumbersome procedures,harsh reaction conditions,and low tolerance of functional groups.Therefore,the application of carbonylative strategy for heterocycles synthesis will become an important area of synthetic development.However,CO gas is odorless,toxic,and hard to handle.Thus,the development of CO source become a hot pot in carbonylation field.In this dissertation,we developed a palladium-catalyzed carbonylation reaction with formic acid as a cheap and easily available CO source for heterocyces synthesis.This approach has the advantages of simple operation,mild reaction conditions,good selectivity and good functional group tolerance.The main research contents of the paper are as follows:1.Palladium-catalyzed carbonylative synthesis of aurones with formic acid as CO source was achieved.Using Pd（PPh₃）₄ as catalyst,Et₃N as base and toluene as solvent,2-iodophenol and a series of phenylacetylene compounds can react well at 80°C and the corresponding target products were obtained with moderate to good yield.2.Palladium-catalyzed carbonylative synthesis of benzylideneindolin-3-ones using formic acid as CO source.Using Pd（PPh₃）₄ as catalyst,Et₃N as base,toluene as solvent,adding mixed anhydride and stirring at room temperature for 2 hours,a series of 2-iodoaniline and phenylacetylene compounds were worked well under anhydrous and anaerobic conditions at70°C,resulting a moderate to good yield of the target compound.3.Synthesis of N-acetyl benzoxazinones via palladium-catalyzed carbonylation reaction with formic acid as CO source.Using Pd（OAc）₂ as catalyst,PPh₃ as ligand,Et₃N as base,and toluene as solvent,a series of now-synthesized Schiff bases were used for carbonylation cyclization to give the corresponding N-acetyl benzoxazinones in moderate to good yields.