A theoretical study of the uncatalyzed and BF3-assisted Baeyer-Villiger reactions

The mechanisms for the uncatalyzed and boron trifluoride (BF3) assisted Bae yer-Villiger reactions between acetone and hydrogen peroxide have been inve stigated using high level ab initio [MP2 and CCSD(T)] and density functiona l theory (B3LYP) methods. Both steps in the uncatalyzed reaction are found to have very high transition state energies. It is clear that detectable am ounts of the Crieege intermediate or the products cannot be formed without the aid of a catalyst. The main function of BF3 in both the addition step a nd the rearrangement (migration) step is to facilitate proton transfer. In the addition step the complexation of hydrogen peroxide with BF3 leads to a n increased acidity of the attacking OH group, while in the rearrangement s tep BF3 takes active part in the proton-transfer process. This latter step is found to be rate determining with an activation free energy of 17.7 kcal /mol in organic solution. The products of the reaction are BF2OH, hydrogen fluoride, and methyl acetate. Thus, BF3 is not directly regenerated from th e reaction.