Palladium-catalyzed Decarbonylative Coupling Reaction Of Aryl Esters And Acylphosphines For C-P(?) Formation

In this paper,the synthesis strategy of using aromatic carboxylates as electrophilic partners and acylphosphines as phosphorus source through decarbonylative coupling to directly construct C-P(?)bonds was proposed.The main research contents are as follows:The Pd-catalyzed decarbonylative coupling reaction of aromatic carboxylates and acylphosphines was studied.In the condition screening stage,the phosphorus source used in the reaction was thoroughly investigated.During the condition investigation,it was found that the commonly used phosphorus source diphenylphosphine did not convert while the acylphosphine developed in our group could react smoothly as a phosphorus source,which reflected the key role played by acylphosphine as a substitute for phosphine hydrogen in the reaction;In order to solve the problem of side reaction of the system,in the selection of acylphosphines,we examined in detail the alkylacylphosphines represented by acetyldiphenylphosphine and the arylacylphosphines represented by benzoyldiphenylphosphine,and finally chose benzoyldiphenylphosphine as the reaction phosphorus source.The optimal reaction conditions was obtained by using benzoyl diphenylphosphine and phenyl 1-naphthoate as substrate models,and the isolated yield reached 79%.Under the optimal reaction conditions,the applicability of the substrates of sixteen aromatic carboxylic acid esters were investigated and the corresponding trivalent phosphine compounds were synthesized in yields of 5%-81%;From the results of substrate universality investigation,it could be seen that the reactive functional groups are well tolerated and have good compatibility with aromatic ring and heterocyclic substrates.Substrates with electron-donating groups on the aryl group and low steric hindrance were conducive to the reaction.In the discussion of the mechanism,it is speculated that the reaction may undergo oxidation addition-reduction elimination mechanism.Compared with the developed C-P bond construction method,this paper realized a new method of Pd-catalyzed decarbonylative coupling to construct the C-P(?)bond by using cheap and easily available aromatic carboxylates as electrophilic partners and the stable and easy-to-storage acylphosphines which developed in our group as the phosphorus source.The method improved the decarbonylative coupling reaction system in which aromatic carboxylic acid esters are used as electrophilic partners,expanded the application range of reactions in which acylphosphines are used as phosphorus sources,and provided a new way to synthesize trivalent phosphine compounds.