[dcm2879]

So typically racemization through enol chemistry is something to be avoided, but I actually want to exploit it, I just don't know if it's such a good idea. Consider the following: Two 6 membered rings are fused, with one of them being a cyclohexanone. One of the alpha carbons of the ketone is a stereocenter, but the reaction that produced it favored the undesired configuration. However, this reaction ensures the proper stereocenter for another carbon, so I'm sort of stuck with it.

What I'm thinking is that in terms of chair configurations of a 6 membered ring, the configuration I want places the substituent at the alpha carbon in an axial position. (the rings have other substituents that lock it, so no chair flipping) That means that when it is formed, the alpha proton will be equatorial, so there won't really be any more enolization at that alpha carbon because being equatorial greatly reduces its acidity. That being the case, if I can get the ketone to epimerize through enol/enolate formation, I should be able to shift the composition of the ketone to that of the desired configuration right? Because if the undesired stereocenter is formed, that is still suceptible to enolization, but the alpha carbon with the desired orientation is not. Right?

If so, what enolization strategy should I use? Strong alkoxide in protic solvent? Would that work? Or some sort of acid catalyzed enol formation... I've never done that before, so any procedure suggestions?

Thanks!

[Dan]

What I'm thinking is that in terms of chair configurations of a 6 membered ring, the configuration I want places the substituent at the alpha carbon in an axial position. (the rings have other substituents that lock it, so no chair flipping) That means that when it is formed, the alpha proton will be equatorial, so there won't really be any more enolization at that alpha carbon because being equatorial greatly reduces its acidity. That being the case, if I can get the ketone to epimerize through enol/enolate formation, I should be able to shift the composition of the ketone to that of the desired configuration right? Because if the undesired stereocenter is formed, that is still suceptible to enolization, but the alpha carbon with the desired orientation is not. Right?

Please upload a scheme, this is difficult to follow in text only form. Without seeing the structure it is very difficult to say whether it would work in your case.

Equilibration of diastereoisomers by base catalysed epimerisation α to carbonyls is a common classical strategy in synthesis. I've usually seen it with alkoxide bases or DBU. Check the literature, there are plenty of examples.