A systematic theoretical investigation has been studied on Fujiwara-Moritani reaction between 3-methoxyacetanilide with n-butyl acrylate by means of density functional theory(DFT)calculations when two types of Pd(Ⅱ)catalysts are employed.In[Pd(MeCN)4](BF4)2 catalytic cycle,a 1,4-benzoquinone(BQ)-induced C-H activation of trans-(MeCN)2Pd(BQ)2+with 3-methoxyacetanilide occurs as the fiirst step to give DC-4MeCN,facilitating the insertion of n-butyl acrylate and β-hydride elimination,followed by recycling of catalyst through hydrogen abstraction of monocationic BQ fragment.In Pd(OAc)2 catalytic cycle,it is proposed that the most favored reaction pathway should proceed in dicationic mechanism involving a BQ-assisted hydrogen transfer for C-H activation by Pd active catalyst(HOAc)2Pd(BQ)2+to generate DC-4HOAc,promoting acrylate insertion andβ-hydride elimination,followed by the regeneration of catalyst to give the final product.The calculations indicate that the rate-determining step in[Pd(MeCN)4](BF4)2 catalytic system is the acrylate insertion,while it is the regeneration of catalyst in the Pd(OAc)2 catalytic system.In particular,the roles of BQ and ligand effects have also been investigated.