Palladium-catalyzed Carbonylative Synthesis Of Benzofuranones And Benzoxazinones With Formic Acid As CO Surrogate

Since 1970s,palladium-catalyzed coupling reaction provides a powerful strategy to construct C-C bond and has drawn continuously attention in organic synthesis.Palladium-catalyzed carbonylation reaction,which insert CO molecule to the coupling reaction,has been used in the synthesis of carbonyl-containing compounds,and played an important role in the medicine,biomedicine and agriculture.Gaseous CO,as an traditional C1 source,has been widely used in industry for their good atom economy and easily accessibility.However,CO gas also has some noteworthy drawbacks,such as high toxicity,gaseous property and rigorous demand for facility,which limits its application in academic research.Thus,many kinds of CO surrogates were reported in carbonylation reactions instead of CO gas.Among them,formic acid,which could release CO gas by the activation of acetic anhydride,and has been utilized as a good CO surrogate in carbonylation reaction.Our research group has been working on palladium-catalyzed carbonylation reaction with CO surrogate,and have developed various CO surrogates in carbonylation reaction in recent years.Moreover,we also focus on the development of new CO source,which had never been reported before.And what I did is palladium-catalyzed carbonylation reaction with formic acid as CO surrogate for heterocycle synthesis,including benzofuranones and benzoxazinone.Furthermore,a general and efficient catalyst-free borylation of aryldiazonium tetrafluoroborate salts with B₂pin₂ has been explored.The main work is as follow:1.Synthesis of benzofuran-2（3H）-one derivatives by palladium-catalyzed carbonylative reaction with formic acid as CO source.We have developed an efficient and general intermolecular palladium-catalyzed carbonylative reaction of phenols and aldehydes with formic acid as CO source.A variety of benzofuran-2（3H）-one derivatives were obtained in moderate to good yields.Furthermore,a convenient intramolecular palladium-catalyzed carbonylative reaction for benzofuran-2（3H）-ones synthesis with 2-hydroxybenzyl alcohols as substrate were also developed,and provided the final products in moderate to good yields.2.Palladium-catalyzed intramolecular carbonylative N-acetyl benzoxazinones synthesis with formic acid as CO source.We have achieved a practical and general reaction for the synthesis of N-acetyl benzoxazinones via palladium-catalyzed intramolecular carbonylation reaction for the first time.Formic acid was used as CO precursor to avoid of using flammable,and toxic CO gas.This carbonylative strategy could be conducted with high efficiency under very mild reaction condition,and a variety of N-acetyl benzoxazinone derivatives were obtained in moderate to excellent yields with very good functional group compatibility.3.Borylation of aryldiazonium tetrafluoroborate salts at room in water phase under transition-metal-free condition.A convenient and general borylation reaction of aryldiazonium tetrafluoroborate salts with B₂pin₂ was achieved.No transition-metal catalyst,additional ligands and additives were required in this strategy.The reaction could be conducted smoothly in water phase,and various arylboronates derivatives were obtained in moderate to excellent yields under very mild reaction conditions.