title: A new mechanism for the Favorskii rearrangement.
abstract: The title reaction was investigated by the use of ONIOM-RB3LYP calculations. A reaction system composed of alpha-chlorocyclohexanone, a methoxide ion and 8 MeOH solvent molecules was adopted. Two reaction channels, the semibenzilic acid mechanism (A) and cyclopropanone mechanism (B), were compared. B is found to be more favorable than A. The rate-determining step of B is the (MeOH)(3) addition transition state (TS3B) to the cyclopropanone intermediate. While TS3B involves a concerted function of MeO(-) addition and proton relays, it has a large activation energy. A new route was found, where the chloride ion evolved at the cyclopropane formation step (TS2B) works as a nucleophile to the cyclopropanone intermediate. Thus, a cyclopentane-carbonyl chloride intermediate is formed with a small activation energy. A new cyclopropanone mechanism is proposed.
authors.affiliation: Department of Chemistry, Nara University of Education, Takabatake-cho, Nara 630-8528, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Tsuchida
authors.forename: Shoko
authors.initials: S
authors.lastname: Yamazaki
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yamabe