Skip to main content
. Author manuscript; available in PMC: 2017 Oct 4.
Published in final edited form as: Angew Chem Int Ed Engl. 2016 Jun 22;55(41):12596–12624. doi: 10.1002/anie.201600547

Scheme 20.

Scheme 20

(A) Agreement between predicted and experimental 13C kinetic isotope effects indicates that C–C bond-cleavage is the rate-limiting step of the decarboxylation mechanism. (B) The two lowest-energy computed transition structures for the decarboxylation of mendelylthiamin in the presence of a pyridinium catalyst involve cation–π interactions between the phenyl group and the pyridinium. Red dotted lines represent cation–π interactions. Blue dotted lines represent hydrogen bonds. Predicted KIEs and enthalpies of activation calculated with M06-2X/6-31G**/PCM(water).