Destruction Then Recreation of Stereocentres Enantioselective Protonations

Destruction Then Recreation of Stereocentres Enantioselective Protonations 

New catalysts for such protonation are being discovered all the time, recently including those based on newer scaffolds [141-145], and such methods are also being used synthetically in tandem processes where conjugate additions to, for example, enones transiently give an enolate that may be protonated enantioselectively in a subsequent step [146-148]. 

In the above examples, the protonation step involves the irreversible delivery of a proton to a reactive intermediate - a kinetic process. It should in principle be possible to carry out the conceptually simpler thermodynamic version whereby a compound racemizes in the presence of an excess of some chiral scalemic compound that in effect provides a chiral environment that maintains an enantiomeric ratio (without the need for a crystallization event). An example of such a thermodynamically controlled deracemization is contained in a seldom-cited paper from 

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Destruction Then Recreation of Stereocentres Enantioselective Protonations 279... 

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