Mechanism of the [(NHC)Au(I)]-catalyzed rearrangement of allylic acetates. A DFT study.

The DFT study of the mechanism of the rearrangement of H(2)C=CHC(CH(3))OCOCH(3) to (CH(3))(H)C=CHCH(2)OCOCH(3) catalyzed by [(NHC)Au](+) (NHC = N-heterocyclic carbene) shows that a low energy path exists, with a barrier of 14.2 kcal x mol(-1), going through a six-membered ring acetoxonium intermediate and where gold coordinates one of the carbon atoms in the alkene system. The qualitative features of the mechanism are not affected by the introduction of other NHC ligands, counterions, or solvation effects.