Enolate chemistry, summary

Summary of Enolate Chemistry 847 [ WHY DO THESE TOPICS MATTER ] 849... 

In summary, the relevant calculations essentially agree with and confirm the different aggregates disclosed previously by studies in the crystalline state and solution. Computational studies become more and more important for evaluating the reaction paths and mechanisms in enolate chemistry, in particular if they are able to confirm or even predict the stereochemical outcome. Examples thereof will be presented with the corresponding asymmetric syntheses. 

In summary, the auxiliary-based enolate chemistry is much less developed for conjugate addition reactions than for aldol additions. It seems that the enantiose-lective catalysis in the Michael reaction (see Section 5.5) has, in a sense, surpassed the auxiliary concept. 

For several tautomeric systems ketones/enols, imines/enamin and others) a distinct reversal of the stability order is observed when going from the neutral compounds to the radical cations, the first use of which in a new preparative a-Umpolung reaction has been documented for keto/enol systems. The present review provides a critical evaluation of the chemistry of enol radical cations in solution with a special emphasis on the Umpolung reaction and the intermediates thereof. Other enol type of radical cations are discussed with respect to their potential to provide a-carbonyl radical and a-carbonyl cation intermediates. Hence, this article does not constitute a comprehensive summary on all enol type of radical cation reactions. All potentials in this review are referenced versus SCE, unless noted otherwise. Potentials measured against the ferrocene/ferrocenium couple were converted to SCE by adding 0.334 V. 

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