representing the breaking and forming bonds, where a value of zero represents no bond and a value of one indicates full bond formation. The resulting free energy surface suggests that the reaction follows a stepwise mechanism (Fig. ). TS1 corresponds to a dissociative TS with an activation energy of 8.9 kcal mol -1 relative to the reactant complex. This reference, which omits the additional entropy cost of bringing the molecules together, was chosen for ease of comparison with Ref. 66. TS1 adopts a chair configuration, with bond distances of 2.08 Å for r C 1 -O LG and and 3.87 Å for r C 1 -O Nu (Fig. ).