title: Base-catalyzed decarboxylation of mandelylthiamin: direct formation of bicarbonate as an alternative to formation of CO2.
abstract: The decarboxylation of mandelylthiamin is subject to general base catalysis (β = 0.26), an outcome that is inconsistent with the expected dissociative transition state in which CO(2) forms along with a residual carbanion. The results implicate a previously unrecognized associative route in which addition of water to a carboxylate followed by base-catalyzed proton transfer and C-C cleavage produces bicarbonate directly. Various reports of the presence or absence of base catalysis in decarboxylation reactions are consistent with the associative route's occurrence in cases where nucleophiles would be generated along with CO(2) in the usual dissociative route.
authors.affiliation: Davenport Chemical Laboratories, Department of Chemistry, University of Toronto, Toronto, Ontario, Canada M5S 3H6.
authors.forename: Graeme W
authors.initials: GW
authors.lastname: Howe
authors.forename: Michael
authors.initials: M
authors.lastname: Bielecki
authors.forename: Ronald
authors.initials: R
authors.lastname: Kluger