Palladium-catalyzed Carbonylation Of Aryl Halides With Formic Acid As The Carbon Monoxide Source

As one of the cheapest C1 Sources,CO occupies an irreplaceable position in the field of industry,but its high toxicity and odorless properties and high pressure equipment demand hindered its wide application in the academic field.Recently,the development and utilization of new alternatives to CO attracted more and more attention from organic chemists,and become a research hotspot of carbonylation chemistry.According to the way CO has been produced,the methods that have been reported can be divided into two categories: ex situ and in situ.The in situ CO generation refers to CO was generated and reacted in the same reaction tube.In this manner,many metal carbonyl complexes and organic compounds such as Mo(CO)6,formamides,(CH2O)n and aryl formats have been developed as CO surrogates.This paper reports Palladium-catalyzed carbonylation of aryl halides with formic acid as the carbon monoxide source and the advancement of this strategy is simple,raw material economy,mild reaction conditions and a wide range of substrates scope.1.Palladium-catalyzed one-pot carbonylative Sonogashira reaction employing formic acid as the CO Source.Various reaction parameters were screened and Pd(OAc)2 as catalyst,PPh3 as the ligand and Et3 N as the base,direct carbonylation of various aryl iodides with different alkynes was achiened in moderate to good yields.2.Palladium-catalyzed carbonylative Suzuki coupling of aryl halides with formic acid as the carbon monoxide source.Various reaction parameters were screened and Pd(OAc)2 as catalyst,PPh3 as the ligand and K2CO3 as the base,direct carbonylation of various Aryl iodides with different Aryl boronic acids was achiened in moderate to good yields.Moreover,this carbonylative Suzuki reaction was also successiful applied to the aryl bromides.3.Palladium-catalyzed carbonylative synthesis of aryl formates under mild conditions.Aryl formates have been applied extensively as CO source in transition metal-catalyzed carbonylation reactions.Herein,we wish to report our new results on the Palladium-Catalyzed carbonylative synthesis of aryl formates.With formic acid as the formyl source,good yields of aryl formates can be obtained at room temperature.Remarkably,this is the first catalytic procedure for the synthesis of aryl formates.However,in our continued studies,we found that the real role of palladium catalyst in this system might is Lewis acid.If this is the case,expensive palladium catalyst can potentially be replaced by other cheap Lewis acids to make this procedure more practical.4.A convenient,efficient,and non-reacting CO source in carbonylation reactions:Benzene-1,3,5-triyl triformate(TFBen).The character of TFBen as potent and non-reacting CO source has been proven by the successful synthetic applications in carbonylation reactions.Phloroglucinol is abundant and naturally occurring has been applied as the reusable material for TFBen synthesis.