Reinvestigating the Role of Multiple Hydrogen Transfers in Baeyer−Villiger Reactions

Abstract

A comparison between a tetramolecular mechanism (J. Org. Chem. 2007, 72, 3031) and our previously proposed mechanism has been performed. The results show that the tetramolecular mechanism is less favored in terms of Gibbs free energy, and therefore, the reaction in acidic media is acid catalyzed. The role of the catalyst in the migration step has been corrected and discussed. A new transition state is proposed for this step. The change in the rate-determining step for the cyclohexanone + performic acid reaction supports our results.

Mechanistic Investigation of Chiral Phosphoric Acid Catalyzed Asymmetric Baeyer–Villiger Reaction of 3‐Substituted Cyclobutanones with H2O2 as the Oxidant

“…This reaction pathway is consistent with the kinetic results and the mechanistic proposal by List and Müller, [46] and it is similar to the mechanism of carboxylic acid catalyzed B-V oxidation using peracids proposed by Alvarez-Idaboy and co-workers. [19,22,23] Rationalization of the reactivities of different ketones towards the B-V reaction: The B-V reactions of acetone, cyclopentanone, and cyclohexanone were also examined theoretically, promoted by 1 c and using hydrogen peroxide as the oxidant. Because both the electrophilicity and hydrogen-bonding capability of these ketones can be expected to be similar to those of cyclobutanone, similar reactivity for the addition was assumed for both cyclic and acyclic ketones.…”

“…Most of these studies have investigated B-V reactions with peroxycarboxylic acids as oxidants. [17][18][19][20][21][22][23] Remarkably, even though calculations indicated that the reactions can be catalyzed by general acid catalysis, through hydrogen-bond formation, there are still some contradictory results in the mechanism elucidation with regards to the molecularity and the mode of activation. [21,23] For the mechanism elucidation of the B-V oxidation with hydrogen peroxide, only a few computational studies have been published.…”

“…[17][18][19][20][21][22][23] Remarkably, even though calculations indicated that the reactions can be catalyzed by general acid catalysis, through hydrogen-bond formation, there are still some contradictory results in the mechanism elucidation with regards to the molecularity and the mode of activation. [21,23] For the mechanism elucidation of the B-V oxidation with hydrogen peroxide, only a few computational studies have been published. [24][25][26][27] Carlqvist and co-workers studied the uncatalyzed and BF 3 -assisted B-V oxidation of acetone with hydrogen peroxide using high-level ab initio and DFT methods and found that both steps in the uncatalyzed reaction have very high activation barriers, which is in agreement with the experimental observation that B-V reactions of ketones with hydrogen peroxide does not occur to a significant extent without catalytic activation.…”

“…The multiple interaction mode for the activation of reactants disclosed in the reaction, that is, the catalyst with two different binding sites in close proximity, seems to be a common feature in several mechanistic models proposed for B-V reactions, and a close resemblance in mechanism can be found between the title reaction and catalysis by carboxylic acids, [19,22,23] metal ions, [25] or zeolites, [26] and thus may represent a promising approach for future catalyst development.…”

Theoretical Studies on the Asymmetric Baeyer–Villiger Oxidation Reaction of 4‐Phenylcyclohexanone with m‐Chloroperoxobenzoic Acid Catalyzed by Chiral Scandium(III)–N,N′‐Dioxide Complexes

“…Recently, both theoretical and experimental investigations proved that BV oxidation reactions could be accelerated in the presence of acids. The acid molecule was assumed to act as both proton donor and acceptor, decreasing the activation barrier of the addition step 13a,e,f,i,j. Meanwhile, our experiments also indicated that the BV oxidation reaction between 1 a and m ‐CPBA could occur even without the Sc III – N , N ′‐dioxide complex, affording racemic products in a yield of 19 % 19.…”