Fig. 3: Modelling of the mechanism of elimination of para-aminobenzyl ketols.
a, Theoretical potential energy surface calculated with PCM(H2O)/M06-2X/6-31+G(d,p) for the elimination of species 7, 10 and 20 along the breaking C–C bond (green). b, General chemical scheme of nine different species denoted as Q (where subscript indicates neutral, cationic, anionic and zwitterionic) that are in equilibrium for the protected and unprotected para-aminobenzyl ketol derivatives in an aqueous solution. Species inside a dashed box (QNH-, QOH+ and QZw1) are those for which an elimination TS structure was found. The equation describes the effect of pH on the observed kinetic rate (kobs) and its derivation is described in the Supplementary Information. c, TS structures for the elimination of reactive species calculated at the same level of theory. Green dashed lines show interatomic distances (in angstroms) for the breaking C–C bond. Colour blue denotes nitrogen, orange denotes oxygen, grey denotes carbon and white denotes hydrogen. Intrinsic first-order kinetic constants (k–, k+ and kzw) were calculated from the theoretical activation energies (ΔG‡ in kcal mol–1) at 310 K using the Eyring equation.
