Strategy IX Control in Carbonyl Condensations

Background Needed for this Chapter References to Clayden, Organic Chemistry  

Chapter 27 The Aldol Reaction Chapter 28 Acylation at Carbon. 

The last chapter introduced some good disconnections based on carbonyl compounds as both nucleophiles and electrophiles but avoided all questions of chemo- or regioselectivity. These reactions are so important that you need to understand how to control these issues. All the chief difficulties crop up in the synthesis of the conjugated enone 1. 

This all looks very sound and we met examples in the last chapter. We want the ketone 2 to 

But will any of this happen We want the ketone 2 to form the enolate, but won t the aldehyde 3 form an enolate more easily We want the enolate to form on the less substituted side of the ketone, but won t the conjugated enolate be more stable We want the enolate to attack the 

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