Crossed or mixed Claisen condensations

This involves reaction between two different esters. The reaction works best when osnly one of the esters has a-hydrogen atoms (for the same reasons as for the crossed aldol reaction see Section 8.5.2). 

Crossed Claisen-like reactions can also occur between esters and ketones. The ester generally acts as the electrophile, as ketones are more acidic than esters (i.e. the ketone enolate, which acts the nucleophile, is more easily formed than an ester enolate). For an ester enolate, the lone 

However, the reaction works best when the ester does not contain any a-hydrogen atoms (and hence cannot form an ester enolate). 

Et stands for ethyl (CH3CH2—) Ph stands for phenyl and is an abbreviation for —CsHs (Section 2.2) 

For the formation and reaction of ketone enolate ions, see Section 8.4.3 

The lone pair of electrons on OEt competes for delocalisation onto the carbonyl oxygen 

Propanone is more acidic than ethyl ethanoate 

---