Carbonyl Deprotonation

A variety of bases can be utilized to deprotonate carbonyl compounds.  Usually Li is the counterion although other metals (Na, K etc) have been used.

The most common model to describe the deprotonation of carbonyls is the Ireland Models.

Ireland Model

The Transition state for deprotonation is a balance between eclipsing interaction of α-methyl and the R group on the carbonyl and the 1,3-diaxial strain of the nitrogen ligands and α-methyl group.

R E/Z
OCH3 95/5
OtBu 95/5
Et 50/50
i-Pr 40/60
t-Bu 0/100
Ph 0/100
NEt2 0/100

 

 

References
  • R.E. Ireland; P.Wipf; J.D. Armstrong, J. Org. Chem. 1991,56, 650-657