Problems and exercisesDirected aldol addition
Exercise 1
The lithium enolate of 2,2-dimethylpentan-3-one (ethyl tert-butyl ketone), prepared with LDA, is almost exclusively Z. Which aldol will form with benzaldehyde? Justify it with the Zimmerman–Traxler model.
Exercise 2
Which reagents would you use to obtain, from 3-pentanone and propanal, (a) the syn aldol and (b) the anti aldol? Why are boron enolates more selective than lithium enolates?