Enolate anions transition state geometry with

Axial protonation is not strongly favored. They concluded that in practice this type of experiment is complicated by the fact that protonation of an enolate anion can occur either at the carbon (to give 468 or 469) or at the oxygen atom (to yield the enol). Further reaction of the enol with aqueous acid also yields the two possible ketones 468 and 469. Furthermore, since the protonation steps of this strongly basic anion (either at C or 0) are diffusion-controlled (144), it is possible that the transition state geometries for both reactions resemble the geometry of the enolate anion, so the energy difference between the direction of attack on the enolate is small. 

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