| Abstract
| - Various Baeyer−Villiger (B−V) oxidation reactions were examined by density functional theorycalculations. Proton movements in transition states (TSs) of the two key steps, the nucleophilic additionof a peroxyacid molecule to a ketone (TS1) and the migration−cleavage of O−O (TS3), were discussed.A new TS of a hydrogen-bond rearrangement in the Criegee intermediate (TS2) was found. The hydrogen-bond directionality requires a trimer of the peroxyacid molecules at the nucleophilic addition of aperoxyacid molecule to a ketone TS (TS1). At the migration−cleavage of O−O TS (TS3), also threeperoxyacid molecules are needed. Elementary processes of the B−V reaction were determined by theuse of the (acetone and (H−CO−OOH)n, n = 3) system. The geometries of the nucleophilic addition ofa peroxyacid molecule to a ketone TS (TS1) and the migration−cleavage of O−O TS (TS3) in the trimer(n = 3) participating are nearly insensitive to the substituent on the peroxyacid. The directionality issatisfied in those geometries. The migration−cleavage of O−O TS (TS3) was found to be rate-determiningin reactions, [Me2CO + (H−CO−OOH)3], [Me2CO + (F3C−CO−OOH)3], and [Me2CO +(MCPBA)3]. In contrast, the nucleophilic addition of a peroxyacid molecule to a ketone (TS1) is rate-determining in the reaction, [Ph(Me)CO + (H−CO−OOH)3].
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