Reinvestigation of Acetophenones Oxidation by Performic Acid in Formic Acid.

The Baeyer-Villiger (BV) reaction of acetophenones R-COCH (R = phenyl, 4-methylphenyl, 3,4-dimethoxyphenyl) with performic acid (PFA) in formic acid (FA) as the catalyst and solvent was reinvestigated using the MPWB1K functional in conjunction with the 6-311G(d,p) and 6-311++G(d,p) basis sets. For the acid-catalyzed addition step, we used the eight-membered ring transition structure proposed in our previous work. The calculated and experimental results obtained for the BV reaction under the mentioned conditions lead to the conclusion that our mechanism is more reliable than the one reported by Liu and co-workers, in which the acid-catalyzed first step involves a transition state with a six-membered ring structure.

Molecular disorder in (‒)-encecanescin.

(‒)-Encecanescin (1) has been isolated from the leaves of Eupatorium aschembornianum. Two conformers are present in the crystal structure as a result of molecular disorder. The structure of 1 was established by 1H- and 13C-NMR spectroscopy in CDCl3 solution using 2D NMR techniques (gHSQC, gHMBC and NOESY).

Effects of alkyl groups in the rate determining step of the Baeyer-Villiger reaction of phenyl alkyl ketones: a quantum chemistry study.

In this work, we have studied the substituent effect of several alkyl groups in the rate-determining step of the catalyzed Baeyer-Villiger (BV) reaction of phenyl alkyl ketones with performic (PFA) and trifluoroperacetic (TFPAA) acids, using quantum chemistry methods. Our results reveal that the substituent effect is more pronounced in the migration step barriers than in the corresponding addition step; that could change the rate-determining step (RDS) of the reaction, as observed in the oxidation of phenyl tert-butyl ketone with both peracids. In addition, the effect of the acid/peracid pairs used is also analyzed.

The mechanism of the Baeyer-Villiger rearrangement: quantum chemistry and TST study supported by experimental kinetic data.

The mechanism of the Baeyer-Villiger rearrangement is modelled for the reaction of propanone with trifluoroperacetic acid, catalyzed by trifluoroacetic acid in dichloromethane, using three DFT methods (B3LYP, BH&HLYP and MPWB1K) and MP2. These results are refined and used to calculate the overall reaction rate coefficient using conventional Transition State Theory. The excellent agreement between the calculated (1.

Reinvestigating the role of multiple hydrogen transfers in Baeyer-Villiger reactions.

A comparison between a tetramolecular mechanism (J. Org. Chem.

Substituent effects in the migration step of the Baeyer-Villiger rearrangement. A theoretical study.

Quantum mechanical calculations have been performed on the migration step of the Baeyer-Villiger (BV) rearrangements of some acetophenones, p-RC6H4COCH3 (R = CN, Cl, H, CH3, CH3O) with m-chloroperbenzoic acid. The energy barriers, charge distributions, and frontier molecular orbitals determined for the aryl migration step explain the effects of substituents on the reactivity of these ketones. A plot of the log of relative oxidation rates of the ketones versus their corresponding calculated energy barriers of the migration stage showed a downward deviation for the p-OCH3 derivative.

A new specific mechanism for the acid catalysis of the addition step in the Baeyer-Villiger rearrangement.

[structure: see text] A new transition state of the addition step in the Baeyer-Villiger reaction was found. The role of proton acceptor is played by the carbonyl oxygen atom, and the free energy barrier is 12.7 kcal/mol lower than that previously reported.