The importance of α-aryl carbonyl units,as constituents of many pharmaceuticals and bioactive natural compounds,stimulates the development of new synthetic methods.Due to both atom-economy and high selectivity,transition-metal catalyzed organic transformations have increasingly become a powerful tool for the construction of α-aryl carbonyl moiety.Recently,Martin et al.employed simple,nontoxic and abundant iron salt(FeBr3)to catalyze skeletal rearrangement of α-aryl aldehydes(A)in toluene at 80℃,resulting in [1,2]-Ph shift product(B).Interestingly,[1,2]-alkyl shift ring-expansion product(C)was not observed.To obtain the detailed mechanisms for the rearrangement reaction and to better understand the divergence in product selectivity,we have carried out an extensive density functional theory(DFT)on the skeletal isomerizations of α-aryl aldehydes(A)and proposed a novel double-metal assisted Ph-shift followed by H2O-assisted mechanism(see below).The present theoretical results provide new insight into the mechanism of the rearrangement reaction of significance and rationalize the experimental findings well.